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Fiberglass, resins, fillers and epoxies...

Getting to the point in my build to get busy with the body. For a little back round it's a Spirit body and I will be using the seat insert.

I plan on adding some fiberglass cloth to stiffen and build up some parts of the body, such as the rear of the tub and the windshield mounting area. I also want to reinforce the area were the dash meets the top rail as its very, very thin. I'm going to reinforce the body around the upper lip all around the tub, as well as the fire wall area with plywood.

I also have to repair some damage from shipping. The trucking company broke off one of the ears on the firewall, so I need to repair that. And I also need to build up and repair the lower lip of the dash, I found a big air bubble between the gel coat and fiberglass. The gel coat cracked and fell off leaving about 3" of the lower lip of the dash missing. So I'll need to build that up.

I'm looking for advice on brand names and suppliers for

What would be the best product to glue in the plywood wood floor?

Fillers for low spots in the glass and the dash lip?
We use a product called polly bond to install the insert. It comes from the boat industry. Why don't you give me a call during the week. 1-870-425-5900 ask for me and I'll see if we can send you out what you need. We did a video of installing the insert but I don't know if it has been edited yet. If it has and it is uploaded I will post a link to it here. When put together the lip on the body and the lip on the insert will be plenty strong without wood. We do run a strip of glass over the seam to make sure it does not show a seam line in the future.
Thanks, I'll try to call but my shop is so busy right now, I'm just about flat out from 6:00 to 6:00. It's crazy when the economy slows I get swamped with repairs, everyone wants to repair the equipment they have, instead of replacing it. Not that I'm complaining! I'll really try to find the time I've got all kinds of questions...

I would like to use 3/4" plywood for the floor as I have a few sheets marine plywood on hand. Or would that be too thick? And how about the toe board and firewall? Looks like I could get 1/2" on the fire wall between the firewall and the insert. After every thing is glued up I'm thinking of filling the body with a low volume expanding foam, what do you think? Should help to stiffen up the body and deaden sound a bit.

Love the videos, keep em coming!
I'm not fiberglass expert, but I did just retire from the marine industry, so I watched a lot of people who did know fiberglassing and asked a lot of questions. I have also done 3 fiberglass cars that turned out ok, so what I learned must have worked.

First of all there are two kinds of resin.......epoxy and polyester. Epoxy has some real benefits, but is also much more expensive. Biggest benefit is that it bites into existing fiberglass a little better than polyester. That being said, all of the fiberglass guys we hired to do repairs use polyester, and so have I on all my car and boat projects. If you go to a true marine store you will pay about $ 25 a gallon. If you go to a so called discount marine store like West Marine you will pay $ 48 for the same product. Either find yourself an old time marine store or a fiberglass supply house and save some money.

There are also two main types of fiberglass cloth. One is called cloth and is the woven stuff you see that has a crisscross pattern to it. The other is called mat, and it the one that has strands running in all different directions, and you can tear pieces of it off. Mat is what you want to use because it bonds to existing fiberglass better, and also goes around corners and odd shapes better. I have seen many cases where someone did a repair with cloth and it later on started to pull away.......mat becomes part of the repair. Buy it by the yard at the same place you get the resin. Do not buy the prepackaged stuff, it costs like 10 times as much. Buy about 10 yards to start, you will use it and more.

In my T I have almost 4 gallons of resin and 15 yards of mat. Sounds like a lot, but I also have one very strong body that should never stress crack. :lol:

3/4 inch plywood is ok, but 5/8 is better. Much lighter and plenty strong enough. If you have the marine grade use it, but regular exterior grade plywood is fine, and much cheaper. You will probably put a layer of mat over the entire top and bottom of the floor when done, so marine grade is just overkill. If it makes you feel better, go for it.

Buy yourself LOTS of throwaway brushes in like 1.5 width, and LOTS of plastic mixing cups about 1 quart size. Mix up small batches of resin at a time, just what you can use in about 10 minutes. Once is starts to kick, toss it and mix up fresh resin. Buy a box of vinyl throwaway gloves too, and a gallon of acetone or laquer thinner for cleanup. I buy a 5 gallon can for $ 32 at the local paint supplier compared to $ 16 a gallon if you go to Home Depot.

Precut your strips of mat into various widths and lengths, and cut up lots of them. The idea is to keep adding strips and wetting them out with more resin. This is called "Tabbing." You do not want too much resin or too dry......just enough to make the mat translucent in color. After you do a little it will start to come easy to you. You also want to put down a first piece that is like 2 inches wide, then one that is 3 inches wide, then a final one that is like 4 inches wide. The idea is to progressively get the edge out further so you don't create a sharp stress point.

Ok, my fingers are tired from typing.........hope this helps a little. :):)

Oh, and that empty spot is called a "void." Very common in the fiberglass business, both cars and boats. What happens is that the guy doing the glass doesn't get the mat up tight to the gelcoat, and a bubble forms. All you then have is an eggshell thickness of gelcoat with nothing under it to support it.

What you have to do is grind it out until you get back to good glass, and then use something like tiger hair to fill the void, then use body filler over that to fair it in to the gelcoat.

Thanks a bunch Don, perfect timing as I started this weekend to build in a frame for my doors. I have never worked with fiberglass before and often wondered what the differences were.
Fiberglassing is really pretty easy once you do it a few times. Some people use body filler or tiger hair to bond wood to the body, we did that on my Kid's T because we decided to try Total Performance's method for a change. I still like cutting up strips of mat and putting a few wet layers under the wood and clamping it down until it sets up. That is just me.

One thing is constant will be using a lot more of the supplies than you can imagine. Plastic paint buckets, stir sticks, resin, hardener, throw away brushes, acetone, and vinyl gloves are best bought by the box. You can also save some money by shopping around. Home Depot gets 89 cents for a paint cup, and at the automotive paint store I pay 32 cents each. And thinner, as I mentioned is $32 for 5 gallons vs $16 for a gallon at Home Depot.

I can't stress enough that you will overpay for resin and mat at places like West Marine or Boaters World. I worked for both companies and still bought my supplies elsewhere cheaper than at my employee discount.

Final tip: When wetting out the mat, I paint a heavy coat of resin down first, then press the dry mat into it. Then I take the brush and "Dab" more resin all over it until it is correctly wetted out. If you try to brush it on it pulls the mat all goofy, but by dabbing it on it keeps in in place.

Thanks for all the info, I've worked with fiberglass in the past but it was a few years ago. Mostly repairs to the fiberglass buckets and fiberglass boom sections on bucket trucks. I cant tell you how much fun it is to have to replace a fiberglass boom section :lol:

Mostly I'm looking for product names and supliers.
As far as names go, every area has it's local brands. They usually buy it in 55 gallon drums and pump it into gallon containers, or simply buy it in gallon cans. You should be able to get it for $ 20-$25 a gallon.

BTW, pick up some pantyhose, or raid the little lady's drawer. :eek: Sounds funny, but if you rub them over your skin they pull out the fiberglass slivers that you will get when grinding and working with it. Those paper suits with the hood help a lot too.

I dredged this up while searching for something else, and thought I would add a few thoughts
I have limited experience with polyester, but have spent many years working with various epoxies, both as an adhesive and as a fiberglass resin. One caution about mixing the two, epoxy will adhere well to cured polyester, but the opposite is not always true. Once you start using epoxy it would probably be a good idea to stick with it. Epoxys come in two general types, 4 or 5/1 ratio epoxies (West System, and many other similar brands). and 2/1 ratio epoxies. The 2/1 ratio epoxies are not as readily available at the retail level, but in my experience based opinion, are preferable. Both are available with fast and slow hardeners. The 5/1 epoxies have a pot life similar to polyester while the 2/1 epoxies allow you much more working time, with a slow hardener, even over night. You have to have been caught in the middle of a job, scrambling to deal with an unexpected problem while your glue is going up in smoke to fully appreciate the extra working time. The 5/1 ratio epoxies also seem to me to be more brittle when cured.
If you are interested in a 2/1 epoxy, a good source that I have found is a mail order place in Florida that can be found on the web at, or at 772-489 4070. they also carry a full line of glassing supplies.
One thing about clean up. Ketone based solvents(acetone, lacquer thinner, MEK, toluene etc.etc) will absord into your blood directly through your skin. I used to work with a guy who had to have his spleen removed due to overexposure to these things, or thats what his doctor told him anyway. Denatured alcohol will work for clean up just as well without the nasty side effects.
I use a pie tin to mix my resin in. I prefer to work with small batches at a time so this works for me. When the leftovers kick off, you can twis the tin and the hardened resin falls right out. Sometimes you need to tab in an area that is hard to reach with a brush. For this I just wet the mat in the tin and press it in place with my fingers.

Don gave a very good procedure for tabbing. The only thing I would add is before you start adding wood to the body, scuff the surface up with some 80 grit sand paper. When the body cures, a film of wax appears on the inside. You need to remove this for the best bonding.

A note of causion here. Any time you sand 'glass, wear a resperator or at least a partical mask. You DON"T want to get 'glass fibers in your lungs.

I rub baby oil on exposed skin before working with 'glass. When your done, take a hot shower. Don't through your clothes in with the regular wash. Mama isn't going to be happy with you when she starts itching.

'Gass is easy to work with. Just remember to take your time and preplan each batch.

I have a body that I want to wood later this year. Hope to do a tech on it. That might help some of you who are thinking about doing this too.

I use gallon milk jugs to mix resin. I cut the top and side but leave the handle to move it around. When it dries flex jug and you are ready to go again.

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