Fiberglass Armor Construction: Lay the Fiberglass
Lay the Fiberglass
This is the big step, the one where you are actually creating the final piece that you will paint and wear and wow friends, neighbors, children and small woodland animals with.
But before we start, a few words on safety. When working with fiberglass and fiberglass resin safety should alwyas be on your mind. The fumes that the resin releases are strong, like a take a few whiffs and go throw up strong. So here are a few safety rules that I strongly urge you to follow.
You can get the fiberglass and the resin at a variety of different stores. Depending on where you shop you will have basic options of cloth and mat or a selection of different cloth and mat weights. Some places like Tap Plastics even give you a choice of different materials including all kinds of fancy stuff like carbon fiber. For our needs all we need is a nice medium weight cloth and a medium weight mat. The cloth has a nice smooth and woven look to it whereas the matt is jumbled and messy looking. Usually both are used together to get the best weight to strength ratio.
As with most of the pieces we are making, the size and shape determine the best mix of cloth and mat to use. For example on a small piece that will have no pressure on it, like the wrist pieces, all you need are a few layers of the cloth. As the piece gets larger or is going to have more stresses placed on it the more mat you will want to use. For the chest plate I used 3 layers of cloth and then 2 layers of mat, plus and extra layer of mat at the edges for reinforcement. For the knee cover of the shin amour I added a few more layers of mat to make it look thicker and to give it support so it would not break if I were to kneel on it. You will always want to start with at least one layer of cloth. The cloth is smooth and provides a better surface on the finished end. I have found the following guidelines to be helpful in figuring out how much of each to use.
Similar to the water based fiberglass and burlap, mentioned previously, you will want to cut out enough pieces of glass from the sheet to fit over the whole mold. Each piece should generally be between 10 and 20% of the size of the mold. If there are lots of complex curves and angles you will want to make the pieces smaller. Large pieces have a tendency to crease when put in awkward spots with lots of curves and angles. Often those creases will become air pockets. Those air pockets will decrease the strength of the piece and if they show through to the front of the piece they will have to be filled. This means extra work. So it is a good idea to take the time and have smaller pieces that fit better. Remember, when cutting the pieces out, that they will need to overlap each other so be sure to cut extra. Also, cut extra in case you need them while you are working with the resin. Stopping to cut out extra pieces then when your gloved hands are covered in resin is a very awkward and unpleasant task.
Once you have all the pieces of cloth cut out for the first layer you can mix the resin. You will need a mixing cup, the resin, the MEKP, any dyes you are planning to use and a stirring rod. I find that a nice rubber container works best for the mixing cup. When the resin hardens you can just pop it out. If you cannot find one a plastic painting bucket works, and if not that a disposable paper cup can also work. For a stirring rod I always use a chopstick.
If you want the base fiberglass to have a color you will want to use a dye in the resin. For my armor I wanted the whole thing to be black, even on the backside in case anyone saw. Depending on where you buy your resin they may have a selection of dyes there too. I have found dyes at Douglass and Sturgess, Tap Plastic and a local marine/boating store. I have not seen any at the major hardware stores, as they seem to sell just the basics needed for things like car repair that will be painted. Your local stores may have a better selection. When adding the dye you will usually only need a little bit. I found a few drops were all I needed.
To mix the fiberglass, first pour the resin into the cup. How much you need will really depend on the size of the piece you are making and the type of glass. Mat sucks the resin up much more than cloth. You will have to play around to figure out what the right amount is. Once you get used to mixing the stuff it is always easy to make more, so I generally err on the side of making less and then doing another batch right away if needed. So, first pour in the resin. Then add the color as desired. Then add in the MEKP. Once you add the MEKP the chemical reaction begins and the mixture starts to warm up and you have anywhere from a few minutes to about 15 minutes to work with the resin. I have found that outside temperature and humidity make a huge difference in curing times. Cooler temps and or higher humidity slow things down. The amount of MEKP that you put in also makes a big difference. If you want more working time put in a bit less, though be careful, if you don’t put in enough it will take forever to set and you will end up having to pull the stuff off and start all over. This illustrates a good reason to make smaller batches, if you put in too much MEKP and it starts to set really fast you have not lost a lot of Resin. With the stuff I was working with the directions called for about 15 drops per ounce. Because I live on the coast and it is rather humid here I usually went with about 20 drops. This is something else you will have to play with to get a feel for what works best for you and the area you are in.
After adding the MEKP give the mix a good stir and take the paint brush (I find the one inch cheap bristle brushes you can find at every hardware store to be the best size and type) and a piece of cloth. Lay the cloth on the model (I usually start somewhere in the middle and work my way out) and brush the resin onto it. Be sure to fully cover the piece and let the resin soak in. While brushing it on keep an eye out for air bubbles. If I find them I use the brush in a stipple fashion to pop it with the ends of the bristles. Take another piece of glass and overlay it slightly on the last piece and brush the resin on. Continue until the whole piece is covered. As you get to the edges of the mold I suggest that you lay the fiberglass a bit past the edge. This will ensure that when you cut the excess away you will have a nice piece that does not have gaps, or thin spots, from missed areas because you did not get close enough to the edge.
Once done give this layer a chance to harden. You can leave it for as long as you wish but don’t rush back to add the next layer. Patience is good. Wait until the first layer has hardened enough to be firm but tacky.
When you are ready to add the second (or any other layers for that matter) you will do the same thing as above. Cut the mat or cloth to the right sizes, mix the resin, lay down the glass and then paint over it with the resin. Remember as you work with the mat that it will suck up much more resin. Also, the matt is usually less flexible than the cloth so you may have to make the pieces smaller if there are a lot of complex shapes.
Continue until you have the right combination of thickness, strength and weight. Although fiberglass is relatively light a few layers of mat and resin do add up and the weight does become substantial after a while (especially if you are going to be wearing this for a good part of the day)
Once you are done with each layer you will want to put the brush in a jar (a glass jar is best as Acetone will eat through a lot of other containers) of acetone. Acetone is really good as dissolving the resin from the brush so you can save the brush and reuse it a few time. Dip it in the acetone and clean it off then leave it out to dry.
When you are done give the piece a few hours to cure. Once it is no longer tacky to the touch you can safely remove it.