Fiberglassing Guide:

This page is going to be dedicated to showing the process my father and I went through in constructing the tanks/troughs for the system at school.

When dealing with epoxy resin it is very important to wear gloves at all times, and avoid getting on skin. If you get resin on your clothes it will be permanent.

Step One: Construction

Construct your tank/trough out of plywood. Essentially just the basic assembly of a box, we use gorilla glue in addition to the 2'' screws to help keep our woodwork strong.

Pics of the construction:
Between every two pieces of wood we applied water proof gorilla glue for an extra strong hold:

Step Two: Making Paste

The next step is to start the seal on your tank. To do this we make an epoxy resin paste and apply to the joints of the tank. In order to make this paste we follow these steps:

Epoxy Resin Paste:
1) Get 1 part hardener to 3 parts epoxy resin.
2) To do that you: Tare your scale. Pour in hardener, weigh on scale. Multiply that number by 3 and tare scale again. Fill up cup with epoxy resin until you get that multiplied number. Mix well. (very important)
3) Slowly start adding sawdust (aka wood flour) and mix until you get a texture close to a paper mache.

Step Three: Sealing Joints

It is very important that your paste be the right texture because if it is too wet then it will get all over the place and not make a good seal. If it is too dry then it will be a pain to apply well. A good rule of thumb is its generally better to have more saw dust then less.

Once your paste is complete you need to apply it to the tanks. The technique to this is to add extra paste on the joints and then do one sweep with your joint tool to get the extra paste off. Then with your finger (MAKE SURE YOUR WEARING GLOVES AT ALL TIMES) you smooth out the paste and shape it nice and neat. When this wood paste drys it becomes extremely difficult to sand off or reshape so you want to make sure you do a good job, keep everything clean, and use an adequate amount of material.

Here is a close-up of the paste on the joints. Unfortunately this is a bad example because it was from a batch of paste that wasn't really up to par. I had used a saw dust that had chunks in it which made it less effective. Another tip is to make sure you are using as fine saw dust as possible. One thing you can do to prevent using bad saw dust is put it through a screen to obtain a higher quality saw dust.

Here is a picture of the trough completely sealed:
Now you give the trough some time to dry and then the next step will be applying the fiberglass in the morning.

Step Four: Sanding & Cutting Fiberglass

After giving your tank/trough's pasted seal time to dry you need to come back with some sand paper and clean up the fillets. Your goal is to make sure its all smooth and all the jagged points are taken out so they don't rip your fiberglass. Its good to just give the whole inside a quick sanding to get rid of any fallen pieces of paste that may have dried. If you were careful when applying the paste this process should be easy but if not... you're in for a treat.

Once the sanding process is complete you need to clean out all the sawdust/particles with either a shop vac or just by flipping it over and emptying it on the ground. For bigger tanks you will need to use the vacuum though.
Now your ready to start the fiberglassing process so you need to measure out the first surface to get fiberglassed, which will be the bottom, add an extra inch on each dimension and go cut out your fiberglass.

Step Five: Applying the Fiberglass

The first surface you will work with is the bottom. It is the hardest section of the tank but is important you do as best a job as possible. To start you will need to mix up a batch of your hardener/ epoxy resin, just like before it will be in a 1:3 ratio. Now you apply the mixture to the bare wood on the bottom. This will saturate the wood and get it ready to apply the fiberglass. Make sure to only use 1/2 of the mixture so you can save the other 1/2 for working into the glass cloth. It is important to saturate the wood first to make sure there is a good bond between the wood and fiberglass cloth.

Use your tool to spread it around evenly. We use a slow drying epoxy resin so you have about 40-60 min to get it on nice but your goal should be to work as fast as possible. With other fast drying epoxies you may only have 20 min tops before it sets up.
As soon as you have the wood saturated you will now get your fiberglass cloth and carefully put it down. It can sometimes be hard to move after you put it down so do your best to have it centered. If its off do your best to pull it until its adequately centered.
After placing the fiberglass down pour the rest of your mixture on top of it and start spreading it out evenly. Work from the middle to make sure you work out any air bubbles that might occur. Its important to know that how it dries is how it will stay so do your best to do a good job. Remove any build up of junk other wise you will be sanding it over and over.

Here is a picture of the finished bottom:

Step Six: Repeat, Repeat, Repeat

Now that you have completed the bottom you need to repeat the same processes until you have done each side. Each side will be done twice and then the bottom outside will be done. The outside panes be coated with a layer of resin and then painted with a good grade exterior latex paint to protect epoxy resin from the sun.


Step Seven: Corners

If you are making a tank that will need to hold a lot of water it is a good idea to put fiberglass on the corners to prevent leaks and strengthen your tank.

Step Eight: Epoxy Resin

After you have fiberglassed all sides of your tank/trough two times then your ready to paint on the epoxy resin. Do a final sanding and clean up of your tank.
Mix up your hardener/resin mixture and use a roller to toll the outside with the mixture. After giving it time to dry the next step is to roll the inside.

Step Nine: Cleaning

After giving time for your tank/trough time to it is important to take a cloth and wipe it down. You should see some white foamy material coming off when you wash it.