Fiberglass Armor Construction: Painting and Gel Coating
Painting and Gel Coating
For my armor I wanted to go for a more magical look, given the nature of the Rayearth series. I did not think I could get the mirror-like finish that I wanted from paint, so I decided to use gel coat instead. Most of this page will talk about gel coat as I do not have as much experience with painting the fiberglass and there are plenty of painting resources on the net.
There is a huge selection or paints out there that you can work with. I have little experience with most of them so I cannot offer much firsthand advice. You can always bring your piece into an art store to show them ask if they can recommend a paint that will stick and be durable. Although I have not used it I do know that some of the nautical paints used for boats that you can find at marine/boating stores are very nice and very durable and can even be polished after being painted on. If that is something you are interested in I suggest contacting a place like Tap Plastic or West Marine for more info. Oh yes, one small piece of advice on painting. Invest in a good brush. The quality of the final piece and the lack of lines due to the higher bristle count of a quality brush makes it well worth the investment. Alternately, if you have access to, or buy, an air brush you will will be able to get some great results, however some of the thicker paints, like gel coat, might be too thick for most airbrushes.
For both painting and gel coating you may want to make a stand for the piece so that you can paint all the way around it, including the edges without having to stop or worry about messing any of it up. To do this I took one of the stands I made earlier and a ball of plasteline. I mushed the plasteline onto the back of the piece of armor and then set the pipe from the stand into that. The piece was very stable and I was able to work with it and rotate it around without any problems. It made painting much easier.
Working with the gel coat is actually a lot like painting. It is the finishing that is different. As with the fiberglass work you want to use the same precautions when working with the gel coat, as it is just as potent of a chemical that you do not want to be breathing. Above I mention that having a good quality paint brush will make the results much better for painting. If you are not planning to sand the gel coat after it cures the paintbrush is just as important here.
Generally there are two ways to finish with gel coat. One is to paint on the gel coat and then sand and polish. The other is to use a surfacing agent on the gel coat so that layer touching the air will cure properly. I will cover both methods.
When the piece is ready to be painted you can mix the gel coat. First pour some in a container, mix in any colors that you need (gel coat usually comes in clear, white and black) then add the MEKP. With gel coats the instructions I have seen usually call for adding more MEKP than you would for plain resin. Most call for 20 drops per ounce and I usually go for about 25-30 given my environment.
I have seen two types of surfacing agent (Surfacing agent causes the outer layer of the gel coat to cure properly. If you do not use it the outer layer will be somewhat tacky and you will have to sand it.). Although I have not used it, there is a type that you can add to the mix, it seems like the best choice if it is available in your area. If not, you can brush a thin layer of the PVA mold release onto the top of the gel coat and you will get the same result.
If you are going to be using a mix-in surfacing agent you will want to add that to the mix now.
Now paint the gel coat on the piece. If you have masked the piece off so only certain parts are going to be painted with the gel coat keep in mind that the mixture cures quite thick, so there will be an edge when you remove the masking tape. If you are planning to use the surfacing agent you will want to use a nice brush. If you are going to sand it you can use the cheap foam brushes. The foam brush will leave a nice relatively smooth result, but I find I do not get the same level of control from the foam brush as a bristle brush. Paint on your first layer.
If you are planning to paint on multiple layers (I generally like to have at least 2 layers) then give the first layer time to cure to a tacky stage. At that point you can put on the second layer.
When you are done with the final layer you will want to brush on the surfacing agent, if you are using that method. I use a basic foam brush for this. It works well and does not leave any marks. Be sure to wait until the gel coat has cured a bit before doing this.
If you are using a nice bristle brush you will want to clean it in acetone after every use to protect your investment. If you are using a foam brush you will just throw it away as once the gel coat dries the thing becomes like a rock.
If you are using the surfacing agent method, once the piece has cured you are done. If you used the brush on surface agent you will want to wash any residue off with warm soapy water. Congratulations, the piece is done and ready for any mounting rings, backing or whatever other finishing needs to be done to it.
If you are going to be sanding the piece you will wait for the gel coat to cure, but when it cures the outer layer will still be a little bit sticky. This is normal and the sanding will take that off.
All the sanding we are doing on the piece will be wet sanding. If you do not do wet sanding the paper will get clogged with the dust, which is very fine, and quickly become unusable. Also, since this is wet sanding you will want to do this by hand given that water and electricity are not a good mix if you plan to be alive long enough to wear the piece. So grab a bucket of water and dip the sandpaper in it. Starting with a 400 grit paper sand out any ripples or bumps in the gel coat. When everything is smooth wash the piece off well, dump the water, rinse out the bucket and get a fresh bucket of water. Now move up to 600 grit sandpaper and sand everything smooth until you do not see any scratches in the piece. You will notice that every time you move up a grit level there will be “scratches” from the previous grit that you have to sand out. So give the piece a good sanding at this grit until the scratches are gone and then rinse the piece off and get some fresh water.
The reason to replace the water each time is so that no grit from the previous grit size contaminates your sandpaper and causes a bunch of new scratches. After the 600 grit you can either go directly to a 1500 grit or go through a few more steps. Based on what my local hardware store had I went right from 600 to 1500 grit. The 1500 grit is so fine that you are almost polishing the piece. You will want to spend extra time here to make sure that there are no scratches left in the piece. Once you are done with the 1500 grit the piece is ready to be polished.