How to Fiberglass

How to fiberglass - We're just getting started with this area so we don't have much done yet. Here's a few general things you might already know but just in case. We don't pretend to be experts but just won't to help the person who's just getting started and would like to skip some of the really hard learning challenges most of us have had to endure.

One thing I want to say from the start is that fiberglassing is not easy. Anybody that says it is must be a lot smarter than I am. I think it's one of the least forgiving things a person can do. Murphy's law is in full effect when it comes to making stuff with fiberglass. One important thing to know is that resin goes from a liquid to a solid and stays pretty much where it's at after it's no longer in the liquid state. I know this sounds childish but if you get it on your clothes you'll have a hard spot there later. It won't wash out. If you get it in your hair you can wash it out somewhat with shampoo before it cures but it will be with you for a while if it cures before you get it out. You can cut it out or whatever - no big deal. Don't breath the vapors. Epoxy and Polyester are both pretty bad - Polyester is more of an obvious smell. What you're smelling with polyester resin is the styrene monomer. With epoxy the hardeners are more vicious than the resins. That applies to the skin also. For hands I use Ply #9 or other barrier creams. I've done a lot of layups with just ply #9 on. Feels kinda icky but later I go and wash up and it comes right off. I have used a lot of latex, vinyl and nitrile gloves. I've been in a lot of epoxy resin and have never had a reaction to it though some people have. Some people have built up allergic reactions to epoxy resins such that just entering a room will cause them to have rashes and the like. So be careful and be protected. I never use any kind of organic solvents like acetone or mek on my skin - just don't feel the risk of cancer is worth it. Wear respirators when the resin vapors are heavy and particle masks when grinding or cutting cured fiberglass.

Be sure to prepare the surface you're going to fiberglass. If you sand or grind be sure to clean the debris off with a shop vac or blow off the area well. Make sure there's no water of any kind. If there's moisture dry with a hair dryer or let it dry or whatever. High humidity will keep polyester from curing. Epoxy parts will not be as strong. Make sure the working temperature is adequate - 75 deg Fahrenheit. You'd generally wet out the area with resin then lay cloth on. Have the cloth precut and ready to put in place before mixing the resin. It's a good idea to try the cloth to be sure it's going to lay down where you want it before you mix any resin also. If it won't stay down while it's dry don't expect it to when you put resin on it. Radius any sharp corners. Meaning if you're going to layup around a 2 x 4 board file the corner off to a smooth curve. If I'm doing small stuff I like to have an extra project of some kind to use any left over resin. If you're doing something with a lot of curves use some cloth like 7781, 7725, 7533, 1522 or some easily pliable material. I like to put a layer of peel ply on at the last. You can squeegie the peel ply and get a much better final shape. Unless your layup is really wet you'll want to add a little resin to be sure not to dry the cloth out underneath. Don't leave the peel ply too wet though. If there's extra resin on top of the peel ply it'll hinder the peel ply removal later. If there's wrinkles this will keep the peel ply from coming off later also. Be sure to leave some extra unwetted peel ply around the outside of the layup to give you something to grab later to remove it. Be sure to remove all peel ply after it cures. If any gets left in the laminate any secondary laminates over it will delaminate later. Using peel ply will greatly decrease but may not eliminate the need for sanding after cure.

Hints and notes - no particular order

The styrene in Polyester resins will dissolve styrofoam - Most epoxies work okay on styrofoam. If you want to make a straight cut across the cloth pull a fill yarn thread out - this will give you a straight line to go by. If you're cutting Kevlar make one pass on the cutting part of each blade on a bench grinder. Done with skill this will work excellent. Keep a pair of scissors dedicated to just cutting kevlar and other materials besides carbon and fiberglass. Always squeegie the resin from the middle of the material out. Mix small batches of resin at a time - even on large layups. The thicker the resin is the more exotherm it will build and the faster it will cure. Mix too much and the resin will cure before you get it all used up. If it starts gelling throw it out - don't try to use it on your part. You can hot wire polystyrene foams but no others. PVC and polyurethanes give off some nasty gases when they burn. If you're doing layups over foam you can save weight by mixing a slurry of hollow glass microspheres to the resin in about a 1/1 by volume ratio. This will help fill the voids and be lighter than having pure resin in the low spots. Don't use micro between the layers of the cloth though - this will cause delaminations. Lay the cloth on before the micro cures or you'll have to sand the whole thing. If you use Kevlar in your surface layers and later sand it it will fuzz up on you.

I'll be back later to add more as I have time