Solar Concentrator Layups

Materials Exploration for Solar Concentrator Dish Group Project

Layup 1.jpg

Q: What is going on in this picture; what are you doing?A: We are blending cement, latex paint and water into a mixture that is set onto canvas material on top of a mold with chicken wire as a reinforcing material. We believe that this will form a solid base (a layup) from which to build a solar concentration device. The cement will dry within the canvas material in a parabolic shape on the back of the plastic mold.

Goals for Our Solar Concentrator Lay Up GroupThe goal of the solar concentrator layup group project is to develop an understanding of what materials could be used to build a solar concentrator layup (mold) that can be used as a background for reflective material to be placed into. The key is to use materials that would be readily available in the developing world. There are many modern versions of solar concentrators available but they are not considered to be sustainable or appropriate for many communities around the world.

Introduction – The Global Energy Crisis

The global environmental landscape of our time has demanded that we examine our consumption and energy use as we see that existing technologies are no longer sufficient as they consume too many natural resources. Along with a shift in awareness of our impact on the environment, there are also shifts in the economy and culture.

Countries that were previously dismissed as third world have grown their economies significantly and are eager to become financial secure. This puts an even greater burden on our energy resources as the existing technologies are not sustainable, yet they keep getting used. Alternatives must be explored and actually deployed, otherwise the future for our Earth

What is our greatest natural source of energy?
The energy from the sun fuels every reaction on Earth and is therefore our greatest resource. It is naturally available year round and it is also free! It is therefore an ideal resource to tap into in our energy crisis! Solar power has greatly evolved over the years, as can be seen in The Evolution of Solar Technology diagram to the right.

How does solar energy connect to providing a solution to the energy crisis?
A core cultural ritual in every country is food preparation and eating. All humans must eat and most cook at least some part of their meal, if possible. Currently, the conventional way to cook food is over a fire, which uses wood as fuel (generally), or a gas stove, which uses natural gas. Both of these natural resources are severely depleted and we cannot keep using them at the rate that we do. However, cooking food has many benefits and proposing to completely abandon it is unrealistic. The technology that is now conventionally used to cook food is not sustainable and therefore, there is a need to figure out an alternative method to cook food throughout the world rather than perpetuating the current technologies or simply patching up the problem even more.

What is Solar Concentration?
Solar concentration involves focusing the solar energy to create heat at the point of focus. This method can be applied to cooking and a solar concentrator, a parabolic dish, can be used to gather the sun’s rays and focus them at a focal point which is then heated to high temperatures to cook food, comparable to a gas stove.

Background on Solar Concentration Research at Cal Poly

Over the years, there have been several solar concentrator models developed by various individuals and institutes. Dr. Schwartz has been working on solar research for the past 3 years with research students.Their work has been on improving the Scheffler reflector, a two axis off parabolic solar concentrator made for cooking purposes.
A mold for such a parabolic dish has already been developed by research students under Pete’s guidance. It is made of fiberglass and while it is mathematically engineered to be the perfect parabolic shape for the Scheffler reflector, it is not made of sustainable or appropriate materials. It cannot easily or affordably be replicated. This quarter, our group Solar Concentrator Group is continuing the solar concentrator research, aiming to have a final product that is easily assembled, durable, affordable, sustainable, appropriate and usable Scheffler reflector.

But, we quickly realized that the Scheffler solar concentrator design challenge was two-fold:

  1. The construction of the mold needed to be refined

2. The material used for the parabolic dish as part of the solar concentrator needed to be explored (our group!)

~THE GREAT DIVIDE~A Reflection on Group Dynamics

Given our realization, our group split into two groups and we have been working in parallel with the Solar Concentrators in the Earth group (
Our group has chosen to focus on exploring the material that will be put on the mold to ultimately become the parabolic dish component of the Scheffler reflector.

    • How did splitting up into two groups after beginning the project affect productivity and progress on the individual projects?
      • Initially, it was tough for our group to get together and figure our game plan. We didn’t have the best understanding of what exactly our problem statement was and how to go about designing a solution. Our schedules for the first few weeks after splitting up were conflicting and it was difficult to get together to make a cohesive game plan.
    • How did it affect group dynamics?
      • Our group has become more proactive and motivated to communicate and move forward after a bit of a bumpy start. While it was a little frustrating at first to not be able to meet regularly, once we met and got a game plan together, things have been going extremely well! We all work very well together! Instead of being frustrated by conflicting schedules or having to meet at odd times, we have combined a variety of collaborative technologies such as Google Docs and other tools to work independently, yet collaboratively.
    • What was ultimately learned?
      • One of the main things that we learned is that a group project can always be turned around given the right focus and motivation. We got off to a bit of a rough start, given that we split off from the main solar concentrator group after two weeks. We then had to devise a whole new project plan while dealing with other projects and activities. However, we were patient and persistent and eventually, everything clicked!
    • What was the greatest challenge initially and did it get resolved?
      • The greatest challenge initially was finding time for all of us to meet together. We were all extremely busy right at the beginning of the quarter and therefore, we were not able to meet regularly until the week of 2/4. When we met then, we immediately sat down to figure out what progress the other group had made and how we would compliment their process with ours. We made a game plan and have been working cohesively towards our project goals ever since. The challenge did get resolved and our group has been dynamic, flexible, and more effective since we have been able to meet more often.

Problem Statement
Our challenge is to find a material or combination of materials via mixing or layering that would be painted/layered/molded onto the mold that the Solar Concentrator in the Earth group is working on in parallel. Examples of molds from previous projects can be found below in Figures 1-4.

The material would have to be appropriate, sustainable, local (Working Villages & Navajo Nation, if possible), durable, high flexural strength (more rigid), and easily mixable.

It would also be ideal for the dish to be rigid when cured and smooth in order to minimize diffraction of the sun rays in the dish, so that the maximum amount of sun will be captured and focused at a point.

Figure 1: Not appropriate because of the foam mold! But a beautiful fiberglass layup manufactured by a previous group
Figure 1: Not appropriate because of the foam mold! But a beautiful fiberglass layup manufactured by a previous group
Figure 2: A former research student weaving an aluminized mylar -fiberglass strip
Figure 2: A former research student weaving an aluminized mylar -fiberglass strip

Figure 3: Previous research groups had a beach day and made a mold in the sand!
Figure 3: Previous research groups had a beach day and made a mold in the sand!
Figure 4: The foam mold from which the above dish was constructed
Figure 4: The foam mold from which the above dish was constructed

Project Goals

  • Figure out an optimal material or combination of materials and layering to lay over the parabolic dish mold produced by the Solar Concentrators in the Earth group to result in a rigid parabolic dish after curing
  • Through parallel development processes create a mold which is affordable, accessible, and appropriate for the relevant communities
  • Minimize cost
  • Minimize complexity

More appropriate! Plaster of Paris mold shaped by hand. Alternative materials could be investigated.
More appropriate! Plaster of Paris mold shaped by hand. Alternative materials could be investigated.


  • Making it with materials appropriate for the communities of Working Villages & Navajo Nation, Arizona
  • Affordability, flexibility, durability, water damage, working parallel with mold group to find cohesive solution with the mold being in the Earth, rigidness vs. flexibility, accessibility to materials
  • How do you mix the cement efficiently, sustainably & appropriately?
  • Reducing cracks on cement when curing in dish shape
  • Making the shape smooth

General Design Process

  • Convex mold (i.e. plastic dish shaped snow sled, bowl, etc.)
  • Research on layup materials (i.e. latex concrete additives, clay, mortar, layering, sand)
  • Trial and Error with individual materials & combinations of materials w/layerings

Design Matrixes


Construction Ease Cost Robustness Weight Availability
Plaster Easy Cheap Rigid Light Available
Adobe Easy Cheap Rigid Heavy Available
Clay Easy Cheap Rigid Heavy Available
Latex Concrete Easy Somewhat expensive Flexible Light May be difficult to find all materials
Chicken wire/mesh Easy Relatively cheap Flexible Light Available


Construction Ease Cost Robustness Weight Availability
100% Acrylic Latex Paint Easy Medium Flexible Light Available
Acrylic Cement Fortifer Easy Medium Rigid (meant to fortify cement) Light Substitute may be available
Sand Easy Cheap Rigid (meant to fortify cement) Medium Available
Elastomeric Paint Easy Bit more expensive Very Flexible Light May be difficult to find & too expensive


Construction Ease Cost Robustness Weight Availability
80% Gardening Shade Clothe Easy Medium Flexible Light May not be available everywhere
Denim Easy Cheap Flexible Medium Available
Reusable Bag (recycled cotton & hemp) Easy Cheap Flexible Heavy Available (or cotton substitute)

Lab Log & Notes

Lab # 1 on 1/28 – Tire Oven

external image tire_c5.jpg

What We DidAustin worked on making a solar tire oven.What We Learned
What’s Next

Lab # 2 on 2/4 – Clay Lay Up

Clay over plastic dish mold
Clay over plastic dish mold
Clay dried over dish mold after rain. Notice the severe cracking and how the clay seems to have slid off of the mold onto the wood panelling below.
Clay dried over dish mold after rain. Notice the severe cracking and how the clay seems to have slid off of the mold onto the wood panelling below.

What We Did
We wanted to see how clay would lay up on a dish shaped mold. We used Earthenware Clay (“common clay”, which is red, rough and opaque) to lay over the dish mold. We then allowed it to cure outside in the sun until our next lab!

What We Learned
This clay does not do well in rain!! It had rained since our last lab and when we arrived, we found the clay to be severely cracked and deformed. The rain had caused some of the clay to slide off of the dish mold and onto the ground next to it. The dish did not retain its shape. This approach did not work the best and also, clay is not as weather resistant as we would like.

What’s Next
We want to move away from clay and try experimenting with other materials. We have been doing some research regarding latex cement and are working out how to apply it to our project. We think it is a very viable option and we are gathering materials to begin mixing latex cement next lab!

Latex-Cement Research & Experimentation For Lab #3 on 2/11

What is Latex-Cement?

    • Latex-cement is composed of Portland cement, sand, and a latex binder. Some latex cements are dry and must be mixed with water, while others may come in liquid form.

Uses for Latex-Cement


    • Latex-cement uses a number of different specific polymers to provide more flexibility, greater-water resistance, and less shrinkage when added to concrete.
    • Superior adhering properties (can be using for setting down tiles)
    • water-resistance
    • resilient to salt & many chemical compounds
    • Can be applied with a brush or stick; essentially it can be painted on

Problems with Latex-Cement

    • more complex than traditional cement (need polymer additive) therefore costlier
    • thickness of more than 1/4 inch requires multiple layers
    • extremely flexible & cannot hold shape of parabolic dish with only one layer

Materials Needed

    • Acrylic Latex (100% acrylic concrete bonding agent)
    • Cement
    • Fine screened sand (to be added as needed)
    • Paint
    • Loose weave-fabric – like nylon netting or shade cloth
      • You want a fabric with a relatively loose weave, so that the latex-cement can fully penetrate it. The thing to look out for is penetration: you want a coat from the top to penetrate all the way through the fabric without falling right on through.
        We used 80% shade cloth.
    • 5 gallon bucket or other mixing bowl
    • wooden stick or other more efficient stirrer

Labs Involving Latex Cement

Lab #3 on 2/11 – Latex Cement Lay Up on Dish Snow Sled

Underside of the dish after the latex-cement had cured.
Underside of the dish after the latex-cement had cured.
Outside of the dish when the latex cement cured.
Outside of the dish when the latex cement cured.

What We Did
We got a plastic dish shaped snow sled and laid 80% netted shading over it. We then made a mixture of latex-cement involving 1 part acrylic paint, 1 part water, and 1 part Portland cement. We mixed the latex-cement mixture with forks initially and it took us about 45 minutes or so to get the mixture to be homogenous. The resulting mixture was much more fluid than we expected! It was much like acrylic paint and could be painted onto the mold with a wooden stick and spoons. This was very convenient and made it very easy to apply to a dish shaped mold.

What We Learned
Mixing the latex-cement takes the longest! The forks were rather inefficient at mixing the cement and it took us quite a bit of time to get it to correctly mix. However, once it was mixed, it was very easy to put onto the mold which made up for the difficult work it took to mix! We left the dish to dry cure (not covered) outside and the resulting dish had some cracks and was very flexible (see pictures above). The latex-cement cured quite well for the first trial, and it had minimal cracks. However, as shown in the close up picture below of the latex-cement, the surface is not quite smooth and there are imperfections.

Close up of how the latex cement cures
Close up of how the latex cement cures

What’s Next
We need to figure out a way to get the latex-cement to cure more rigidly. This may involve more layers of latex-cement and also using other materials for subsequent layers. We would also like to look into a mechanism that would make mixing the cement more efficient, as that is a constraint on our lab time.

Lab # 4 on 2/18 (2 Parts to the lab!)

  • Part 1 Make a brand new dish with Latex-Cement, attempting to smooth the surface with a wooden stick and to minimize cracks when cured

Finished latex cement lay up, waiting to cure!
Finished latex cement lay up, waiting to cure!
Close up of latex cement brushed onto 80% shade clothe
Close up of latex cement brushed onto 80% shade clothe

What We Did
We made another mixture of latex-cement with the same proportions as last time. However, this time we made a thinner layer of the latex-cement in an attempt to get it to crack less and be smoother. We made a thinner layer anticipating that it will be flexible. We will then try to layer a more rigid material to the outside.

What We Learned
A thinner layer of latex-cement makes it crack less. It seems that a layer cannot be thicker than 1/4″, otherwise it will not be as effective and will crack. Moving forward, we will keep using thinner layers so that the latex-cement cures better.

  • Part 2Adding the Brown Coat (latex cement + sand) to the dish we made in Lab #3

Latex-cement dish made in Lab #3 without a plastic mold underneath. Notice that is cannot hold it's own weight and is slightly concave on the outside in some areas.
Latex-cement dish made in Lab #3 without a plastic mold underneath. Notice that is cannot hold it’s own weight and is slightly concave on the outside in some areas.
The result of adding the brown coat to the latex-cement. The brown coat with the sand was far too brittle and did not cure well!
The result of adding the brown coat to the latex-cement. The brown coat with the sand was far too brittle and did not cure well!

What We Did
We took the latex-cement dish we made last time and removed it from the plastic snow sled dish we used as a mold (picture in the top left). In the picture above on the left, you will notice that the latex-cement dish cannot hold its own weight and is slight concave in some areas. It is very flexible and has minimal cracks. We wanted our dish to be more rigid when cured, so we decided to add some sand to the latex-cement mixture. The brown coat mixture is as follows: 1:1 acrylic and water, and then add 1:1 cement and finely screened sand. This mixture should be very liquid and is supposed to set much faster than the first coat. However, we were unsure if it would be rigid enough given that it was so liquid, so we added another 1 part of sand to the mixture. Since we only had one snow sled, we fortified the underside of the dish with wooden sticks to make a make-shift mold. The resulting surface was not a perfect dish shape and it was difficult to apply the heavy brown coat. It was much thicker and heavier since we added more sand.

What We Learned
Too much sand!!! In our attempt to make the 2nd layer more rigid, we may have put too much sand in the mixture which resulted in extreme cracking (picture on the right above). Also, we attempted to layer the brown coat without having a really good mold underneath which ultimately led to a deformed and cracked dish. We have not totally dismissed the idea of adding sand to the latex, but are now starting to explore other second layer materials such as clay or we are considering a different composition of latex cement.

What’s Next
We are planning on experimenting with different compositions of latex cement in hopes of getting it to cure better!

Lab #5 on 2/25 – Latex Cement + Reflective Materials & Further Experimentation

Adhering mylar to an existing latex cement dish using latex cement and acrylic paint
Adhering mylar to an existing latex cement dish using latex cement and acrylic paint

What We Did
Pete was around when we were looking at our cured dishes and pointed out that the latex cement may be cracking when curing due to not enough latex in the mixture. He suggested using elastomeric paint as an additive instead of acrylic latex paint. He reasoned that the added polymer mixture (elastomeric paint) would make the latex cement more flexible, as opposed to drying like acrylic paint does. This was not something that we had planned for the lab, however, it seemed like a GREAT idea. His logic made perfect sense to us and we decided to experiment with adding elastomeric paint to our existing latex mixture, instead of experimenting with different amounts of sand and adding in different materials such as clay. We decided that we would research elastomeric paint and acquire it to use in our next lab. We spent some time during lab researching latex cement composition to further aid our anticipated experimentation with latex cement.

Given that we wanted to wait to get elastomeric paint to continue experimenting with the latex cement composition, we decided to test how well reflective materials would adhere to latex cement using an additional layer of latex cement or using just the acrylic paint itself. On the inside of one of our existing latex cement dishes, we took strips of mylar and adhered them to the inside of the dish using latex cement and acrylic paint.

What We Learned
Acrylic latex paint worked relatively well as an adhesive. The latex cement, when reapplied to the already cured latex cement to adhere the mylar, did not work very well. We were able to lift the mylar relatively easily from the dish. Another mixture of latex cement may work better. It also may be better to adhere the mylar or other reflective surface to the latex cement immediately after it was applied to the shade clothe (or other lay on material).

What’s Next
We want to experiment with different compositions of latex cement. We plan on getting elastomeric paint for our next lab and playing around with mixing that into the portland cement, water and acrylic paint.

Our Thoughts So Far on Latex Cement

  • We really like the idea of latex-cement as it is easily applied to the mold with a brush and dries relatively quickly (8 hours). It can also be dry cured and therefore does not require a plastic covering over the mold while curing. However, the resulting dish is flexible and cannot hold a parabolic shape on its own. In order for it to hold its own shape, we will need to either layer on more latex cement and make the layers thicker or explore different materials for outer layers. After some research, we have found that they are a variety of polymer additives to cement that each have specific curing properties. We would like to continue experimenting with materials that will result in a rigid parabolic dish that would not have to be necessary put in the earth. We have also begun to experiment with adhering mylar to the inside of the dish.

Connection to the Solar Concentrators in the Earth group

  • We would like to experiment with laying down latex cement in the Earth and then laying reflective mylar over the latex cement, as it is extremely adhesive. The other group has made a workable mold in the ground and the next step would be to experiment with them and lay the latex cement over the dirt mold. The resulting parabolic dish will be more flexible, however, since the solar concentrator is in the earth, the dish does not need to be rigid.

Lab # 6 on 3/4 – Latex Cement Composition Experiments

What We Did
We wanted to experiment with adding in the elastomeric paint we had acquired from Sherwin Williams to our existing latex mixture (1 part Portland cement, 1 part acrylic paint, and 1 part water). We also wanted to experiment with materials other than shade cloth We were also able to get Quikrite Acrylic Concrete fortifier, which is meant to be added to cement to further fortify it and waterproof it. We ended up making two different mixtures of latex cement!

  1. Latex Cement Mixture # 1
    • 1 part Portland cement
    • 1 part acrylic latex paint
    • 1 part elastomeric paint
    • 1 part water (but add as needed to make the mixture slightly more fluid, but don’t add too much as it will weaken the latex concrete when cured!)
    • 1/3 part acrylic cement fortifier

2. Latex Cement Mixture # 2

    • 1 part Portland cement
    • 1 part elastometric paint
    • 1 part water
    • 1/3 part acrylic cement fortifier
  • note: this mixture is MUCH thicker than any other latex cement mixture we had made so far!

*Note: We used 1 part = 16 0z. In order to cover the snow sled, we needed to increase the mixture composition proportions by 3. So, we ended up using 3 parts Portland cement, 3 parts acrylic latex paint, etc. The above mixtures are meant to show the proportions of the latex cement composition. Please increase all proportions equally if you would like to create more latex cement.

  • After mixing these two mixtures, we poured mixture #1 into the dirt parabolic dish the solar concentrator in the earth group had made. We wanted to see how it would lay up on dirt. We simply poured it into their dirt dish mold and tried to make it as even as possible. We then added square mirror pieces to see how the latex cement would act as an adhesive.

Cured latex cement mixture #1 in dirt mold with mirrors. The cured latex cement was hard and bonded to the dirt.
Close up of the latex cement mixture #1 when cured in dirt dish mold.

  • We also used mixture #1 to paint a thin layer onto each side of a square piece of denim and a square piece of a reusable shopping bag (made up of plastic #1 and recycled cotton) to see how those materials would work instead of using 80% shade cloth. We pierced the denim and reusable bag with nails in order to make them more porous so that the latex cement could seep through. We laid these up on the snow sled in sections to see if they would be able to hold their shape as well. We also used 80% shade cloth as a control group to test if the latex cement mixture itself was viable. We already used 80% shade cloth successfully as a material to lay the latex cement upon so it was the perfect control group for testing our new mixture! We also just painted on a layer of the elastomeric paint directly onto the snow sled to get a better sense of the properties of elastomeric paint.

The reusable bag (left), the denim jeans (middle) and 80% shade cloth (right) are they had been cured. We applied elastomeric paint directly to the snow sled as well, which can be seen as the white spot on the bottom left.
Latex cement mixture #2 poured into dirt dish mold.

  • Mixture #2 we ended up just pouring into another dirt parabolic dish the solar concentrator in the earth group had made. We did not experiment with using it on different materials like denim because it was so thick. Just from looking at it after we had mixed it, we could already tell that it would not work as well as mixture #1.

What We Learned

Elastomeric paint is very flexible when dried! The thin layer we had applied directly to the snow sled was able to be easily peeled off. We could also stretch out the paint while lifting it off without causing it to break. If we were to stretch the paint quickly, it would snap! Interesting! It is definitely better than just using acrylic paint!!

Elastomeric paint when it is cured. Austin is slowly lifting it up off of the snow sled.

Austin bending the elastomeric paint to demonstrate how flexible it is.

Mixture #1 worked EXTREMELY well! The square piece of denim with mixture #1 held its shape well and was flexible. It would, however, crack if we folded it in half. However, since it is much softer than cement, the cracking was minimal and did not affect the overall effectiveness of mixture #1. Mixture #1 on the reusable bag was a success as well. It held its shape and was even more flexible than the denim. We could fold it in half without it cracking at all. It was also possible to rip it in half easily, which was interesting! The 80% shade cloth we had previously used also worked well, but we were most pleased with the outcome of the denim jeans.

Latex cement mixture #1 and reusable bag when cured (outside)
Latex cement mixture #1 and reusable bag when cured (inside)
Cured outside of denim jean pocket covered with latex cement mixture #1

Latex cement mixture #1 and denim jean pocket cured (inside)
Latex cement mixture #1 and 80% shade cloth cured (inside)
Latex cement mixture #1 and 80% shade cloth cured (outside)

Mixture #2 was far too thick. It was very sticky and had too much elastomeric paint in it. It did not cure well and was very difficult to apply. We will probably not only use elastomeric paint.

Testing how durable and rigid the latex cement mixture #2 is. It was rather easy to snap it off. It bonded to the dirt, but could easily be removed.
Side view of the latex cement mixture #2 when it is removed from the dirt. You can see that it bonds to the dirt very well and is about 1/4″ thick.

What’s Next
We want to use mixture #1 of the latex cement on denim and lay it up on the snow sled. We felt like this would be the best combination given our experiments with mixtures and materials in this lab.

Lab # 7 on 3/11 – Latex Cement + Reflective Materials & Further Experimentation

What We Did
We cut Levi jeans into square pieces and laid them over the top of the snow sled after piercing them with nails. We decided that adding chicken wire on the outside of the denim may reenforce the parabolic dish better. This is the process by which we laid up the latex cement onto the denim jeans and chicken wire:

  1. Mix Latex Cement Mixture # 1 from Lab # 6
  2. Prepare the pieces of denim. Poke holes in them using nails to make the denim more porous.
  3. Lay the pieces of denim to completely cover the snow sled. The latex cement will be applied to these pieces and then they will be flipped so that the inside of the dish is evenly covered in cement. We want to make sure that BOTH sides of the denim is evenly covered.
  4. Pour the latex cement mixture over the denim jeans. This should be a thin and even layer across the whole sled.
  5. Once the pieces are evenly covered, flip each piece over individually. The side that has no latex cement on it will now be on the outside.
  6. Once the pieces were flipped, we layered the chicken wire onto the outer layer of the denim. We then attached the chicken wire to the dish using duct tape in order to keep it tightly layered.
  7. Pour the latex cement over the chicken wire & denim to create the outer layer. The chicken wire should be completely covered.

Austin using a piece of plywood with nails nailed into it to pierce holes into the denim. We made this tool ourselves and it was very effective! (Step 2)

Dish covered in denim. (Step 3)

Austin and David pouring the latex cement onto the denim! Notice how fluid the latex cement is! (Step 4)

lab 7 putting latex on jeans.jpg
Applying the latex cement to the outer layer of the denim jeans in Step #4.
Lab #7 putting latex on outside of jeans.jpg
Austin and David applying the latex cement to the denim. (Step 4)
L=Lab #7 Austin applying to both sides.jpg
Austin flipping over the pieces of denim. As you can see, he has just flipped the piece on the left and still needs to flip the piece to the right. This is the “flipping process” we refer to in step 5. (Step 5)

Austin finishing flipping over the last piece of denim! He is applying more latex cement to the piece with his hands. (Step 5)
Austin and David laying the chicken wire over the denim. (Step 6)
Final product before the outer layer of the latex cement is applied. This is what your dish should look like before you pour on the latex cement! (Step 6)

Austin applying the outer layer of latex cement as David helps him even it out with two sticks. (Step 7)

Dish mold covered with chicken wire, denim and latex cement. (Step 7)

Denim, chicken wire and latex cement. Finished product ready to be cured! (Step 7)

What We Learned
The chicken wire did NOT help at all. In fact, it made us put a much thicker layer of latex cement on the outside of the dish. This made the resulting cured dish extremely heavy. It was also very cracked. The latex cement did not adhere well to the denim when it was thick layer of latex cement. We did not evenly apply the latex cement, so the parts that were thicker were able to be easily chipped off of the denim.

However, the thinner parts adhered very well. It seems that a thinner layer of the latex cement would work much better than a thicker layer. This is also consistent with the research we had done that indicated layering would be required for latex cement for anything greater than 1/4″ in thickness. The combination of denim and the latex cement mixture #1 seems to be viable, given that the latex cement is thinly painted on. Chicken wire seems useless and we would not recommend pursuing that option as a material for layering. From our results, the key to getting this combination of materials to work will be to apply to latex cement as thinly and evenly as possible on both sides.

Outlook – What’s Next!

We are optimistic that a composition of latex cement would work very well for the parabolic dish material in conjunction with the denim. There may be materials other than denim that may work better, which is something we would recommend further experimentation on. Also, further experimentation with the latex cement mixture may prove to be fruitful, although we are happy with latex cement mixture # 1. We recommend further experimentation with the latex cement mixture as mixing any kind of cement is actually quite scientific. It is not as simple as adding things into the mixture. The proportions matter in how the cement will cure, how durable it will be and many other factors. Therefore, it is certainly possible to get a latex cement mixture that may work even better than the one that we came up with.

After the results from our last lab, we would recommend to continue this project by starting with creating our Latex Cement Mixture #1 from Lab 6 and applying it to a snow sled dish covered with denim. From our results in Lab 7, we believe the key to getting this combination to work is a thin and even layer of latex cement on both sides. It should be as thin as possible, while covering the denim well. The thickness should not exceed 1/4″, but should be thinner. Should our predictions be correct, this should result in a dish that has minimal cracking and is flexible. Depending on the results, layering on more layers may provide more rigidness.

Note: Please read the above outlook with a skeptical mind. Examine our research for yourselves and do not limit yourselves to using just latex cement! There may be other materials that would work better, even given our promising results. While our outlook focuses on the combination of our latex cement mixture # 1 and denim, we may have missed some key piece of information along the way. We really do believe that the combination is viable, but please keep an open mind and do not fear to question! Happy materials exploring!!! 🙂

Connection to Working Villages

The key question is can this solar concentrator technology be used in the developing world? Do people living in the developing world have access to the materials that are needed to construct a solar concentrator? Will they accept this technology as a means for cooking rather than using traditional technologies?

Alex Petroff

Connection to Navajo Nation, Window Rock, Arizona

Our group member, David, had a chance to work with the Navajo Nation near Window Rock, Arizona this summer. He learned a lot about a part of America that has been overlooked. Most Americans live comfortable lives with easy access to energy to power their homes and fuel their cars. The Navajo people do not have access to all of these modern conveniences. Life on the reservation is not so easy. Many Native Americans do not have their own homes. If they do have access to their own home they may not have access to electricity or indoor plumbing. They also do not have access to natural gas for cooking. Our team believes that it would be a great idea to reach out to this community and see if there would be a need for technologies such as the solar concentrator.

David (from our group!) working at Navajo Nation to build houses.
David (from our group!) working at Navajo Nation to build houses.
Welcome to navajo Nation!!
Welcome to navajo Nation!!
Location of Navajo Nation, Arizona
Location of Navajo Nation, Arizona

Navajo Nation Statistics

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US Per Capita Income per Family over $40,000/yr
Unemployment Rate 6-7%

Navajo Reservation Population: Approx. 180,000+
Median Family Income $22,000/yr (family of 4)
Median Income per Capita: $7200
Only 28% of families have a full kitchen setup
42% Below US Federal Poverty Level
40%+ Unemployment Rate

The data from Gapminder does not show the Navajo Nation directly but it illustrates the income per capita and unemployment rates for different countries in the world. The Navajo tribe with 40% unemployment and very low median income puts the Navajo people below many countries in the world. Another aspect of this that is not captured in the data is that the Navajo live in the US where the US dollar is used therefore such a low income in US dollars is even less than many developing countries because in these developing countries they have cheaper living costs than in the US. Many of the Navajo do not have jobs and are therefore reliant on their local government or the US Federal government for their income. This does not create a healthy environment for the people that live in this area and crime has risen because of the despair that exists here.

Cantina West – Solar Cookers at Navajo Nation
In the summer of 2012, a Boy Scout group from Utah decided to
try and make a difference by donating modern solar cooking devices to the Navajo Nation. These modern solar cooking devices sell from $150 to over $400.

The desert region of the American Southwest does seem to be a perfect area to implement such cooking technologies since there is plenty of sunlight available.

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Team Members

Austin Bertucci (
David Larsen (
Nina Vukicevic (
Mike Kim (

References/Literature Review

Solar Cooker at Cantina West


Navajo Fast Facts

Sustainable Energy Development Navajo Nation 2014

History of Latex Cement & Uses

Concrete: The Basics (scientific approach & useful information for proportioning concrete mixtures)

Scientific Principles of Concrete Mixtures reading material

Understanding Thin-set Mortars and Latex Additives

Instructables link for Latex Concrete Roofs


  • Lab #
  • Date
  • Plan
  • 1
  • Jan 28
  • Intro to shop & red tag test
  • 2
  • Feb 4
  • Tire oven & Clay
  • 3
  • Feb 11
  • Latex-cement & clay experimentation
  • 4
  • Feb 18
  • Latex-cement & clay experimentation
  • 5
  • Feb 25
  • Latex-cement & clay experimentation
  • 6
  • March 4
  • Latex-cement experimentation
  • 7
  • March 11
  • Latex-cement experimentation
  • 8
  • March 18
  • Prep for Final Presentation

Self Interventions with Group – 3/1/14

Nina- For 2 weeks, I will be sorting my waste and composting. I have started a compost pile at my house already and I have purchased additional trash cans to better sort landfill waste, recycling, and other waste. I will try to get my housemates to sort their waste as well! I will also commit to sorting my waste no matter where I am at! If this means that I have to take home things to throw away or hang on to certain trash for longer to find the right place to dispose of it, so be it!!

Reflection: It was a lot harder than I thought! It surprised me how unaware people are of sorting their trash correctly and also how unavailable the correct trash bins are publicly. I found myself carrying my trash around until I could properly dispose of it at home or otherwise. It was also very interesting to try and encourage everyone in my house to sort their trash as well, at least while at home. I made a sign and color coded the trash bins to make it easy for everyone. However, naturally, it was not as simple as that! Visitors that would come over would be unaware and therefore, throw things in the wrong bin. I would then have to go through the trash and sort it before putting it out to be taken away. It was also difficult to set up the compost bin at my house. I have 3 dogs and they run around freely on our two acre ranch. I had to build a serious barrier around my compost pile in order to avoid it being raided by my dogs! They really enjoyed smelling it and would often just hang out right around it (go figure!). All around, I really enjoyed sorting my trash!! It is something that I have continued. It has made me feel like I have a bit more control over where exactly my trash ends up. There are systems in place to recycle certain trash items and sorting your trash correctly allows those systems to work effectively and to their full capacity.

Austin – Committed to eating only things I already own in my pantry and fridge.

David – I challenged myself to not drive my car for at least a week. I was able to do this because I live on campus at Cal Poly. It’s a great feeling to not have to rely on a car to go anywhere. I was able to do this because on campus you have all that you need. I was able to order goods from the Internet and buy food on campus. There was no need to drive anywhere. I also was able to go without a car for a week in Denver when our finance team was there for a competition. We walked over 10 miles around Denver to visit various restaurants and we even walked to the Pepsi Center to see the Denver Nuggets play basketball. I think that if there was a better public transportation system and we were able to live closer to work that we would be able to drive our cars less and walk more. I really liked this feeling that I did not have to be reliant on my driving my car.