Thread: How to Work Fiberglass Right

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Originally Posted by lamin8r

There is no reason,for a fiberglass piece to be larger,Roger,,since a mold is usually taken off the outside surface of that part..If you take a mold from that part,,what comes out of the mold will be the same..... Unless,of course,that the plug is taken out of the mold,,before the mold has finished curing,,in which case,,the mold will shrink slightly..And,,it is very hard to take a mold off a thin plastic item,,or,,as I call it,,a ''street weight'' fiber item..They need to be braced well,,and build the mold slowly,,a couple of layers of glass at a time.. AND,,,DON'T use too much gelcoat in the mold,,as if it's too thick,,it will shrink from the mold as it dries..
For a small item,,I will make my mold about 3mm thick,,built up over a couple of days,and a week of curing..minimum..

See, there's the reason for the question as you jumped right to taking the part that fits and making a mold of it, while my inexperience pointed me to simply using the piece that fit as the mold, making a fiberglass over lay of the part, popping it loose and then working it to finish. Your method is right, taking time to make a mold from the part, built up slowly and maybe even sticking on some ribs for bracing it straight, and then being able to make multiple identical parts out of that mold with a gel goat finish, too.

Originally Posted by rspears

See, there's the reason for the question as you jumped right to taking the part that fits and making a mold of it, while my inexperience pointed me to simply using the piece that fit as the mold, making a fiberglass over lay of the part, popping it loose and then working it to finish. Your method is right, taking time to make a mold from the part, built up slowly and maybe even sticking on some ribs for bracing it straight, and then being able to make multiple identical parts out of that mold with a gel goat finish, too.

I usually look at a mold,as an ongoing item,Roger,unless it's a strictly one off,,which will then only get the minimum requirements.. All my molds are about 5mm thick,,for the auto parts,,coremat on any flat surfaces,in the last few layers,,that is,,under the top layer of glass,,and a piece of 1/4inch mild steel rod around the edges of the mold,to keep the shape.. Over the last ten years,,the molds we bought,have had a check over for fit,etc,,and usually a new part has been developed,,prepped,,painted,,and molded..Our T bucket mold has had 33 bodies out of it now,and requires minimum maintenance..

Jamestown Distributors

Thank you, exactly what I was looking for!

done more fixes with polyester it worked . cost as not has much as the epoxy but it has its place . over the years working with smc i used siwss polyester gell for smc for the big semi flip fronts ends re built many with the gell . many times i was the guy that took the part raw and did finish work to paint with no gell coat on the air plane stuff . last time i was close to a boat repair i did not even work on the damn thing i started getting cold and breaking out.i found out the epoxy i can not be in the same shop with epoxy dust. most repair job were someone did not do a good fix were guys think slopping on to much resin with no mat or cloth

Originally Posted by pat mccarthy

done more fixes with polyester it worked . cost as not has much as the epoxy but it has its place . over the years working with smc i used siwss polyester gell for smc for the big semi flip fronts ends re built many with the gell . many times i was the guy that took the part raw and did finish work to paint with no gell coat on the air plane stuff . last time i was close to a boat repair i did not even work on the damn thing i started getting cold and breaking out.i found out the epoxy i can not be in the same shop with epoxy dust. most repair job were someone did not do a good fix were guys think slopping on to much resin with no mat or cloth

Thankfully,Pat,,the only boat repairs I've had anything to do with,,are polyester layups,,and not GOP,with epoxy..In fact,,i do very little in the boat side of things..We have enough boat repairers in the area to take care of them.. I have a problem with people who come to me,wanting me to fix their broken junk,,and expecting me to do it for very little,,and the parts have been damaged and repaired badly in the past,,and can't see that it usually means more work,,by going down deep in the repair,,and starting with a clean slate,,so to speak,,instead of just slapping more junk on top..

Originally Posted by lamin8r

Thankfully,Pat,,the only boat repairs I've had anything to do with,,are polyester layups,,and not GOP,with epoxy..In fact,,i do very little in the boat side of things..We have enough boat repairers in the area to take care of them.. I have a problem with people who come to me,wanting me to fix their broken junk,,and expecting me to do it for very little,,and the parts have been damaged and repaired badly in the past,,and can't see that it usually means more work,,by going down deep in the repair,,and starting with a clean slate,,so to speak,,instead of just slapping more junk on top..

when i was at the boat yard i never did any glass work. the glass shop was at the very end of the boat yard them guys would do the small fix were the boat was many times i was working on the boat to .seen them fix some nasty stuff we drop off boats many times for fixing in glass shop .i knew i lost brain cell s in that place. i think they kill flys with MEK . jon did the air plane a cars and race boats so the boats were wood then with cloth over the wood so the glass was not flying around the shop less it was a fix were you had to get to the wood and strip back paint for good bond with 8inch pad

MEK was band from our plant. They used it as a solvent for inks. when they used it they had to have a in plant fireman and truck at the job. realy bad stuff. Right up there with Triclorethyline .

Originally Posted by cffisher

MEK was band from our plant. They used it as a solvent for inks. when they used it they had to have a in plant fireman and truck at the job. realy bad stuff. Right up there with Triclorethyline .

yep love the smell of all of it to a point its right up there with nitro. and good race fuel that de icer for them planes sounds lke hot stuff must be alot of hot land /ground water by some of them air ports

AT THE AIR LINE S back in the 60s we used tri clor for washing parts---solvent tanks everywhere in the shop and hangers

Originally Posted by jerry clayton

AT THE AIR LINE S back in the 60s we used tri clor for washing parts---solvent tanks everywhere in the shop and hangers

McDonnell Douglas used it to clean interior panels and just about everything else until, 69, I believe, when some idiot dropped a smoldering rag behind the aft galley in a DC 8 that was ready for delivery. That caused quite a fire that delayed delivery for 6 months or so. That crap will turn your skin white, nasty stuff.

Originally Posted by NTFDAY

McDonnell Douglas used it to clean interior panels and just about everything else until, 69, I believe, when some idiot dropped a smoldering rag behind the aft galley in a DC 8 that was ready for delivery. That caused quite a fire that delayed delivery for 6 months or so. That crap will turn your skin white, nasty stuff.

older engine builder i know said all good carb guys died young from working in the stuff it a liver killer . eats the ozone .but smelled great and did a good job . my dad love to tell me storys when mom was not around . he went in the Army that or jail . he love to out run the cops with is 50 chevy 4 door with red ram in it . well ran out of gas sat on the hood till they found him . Army was a good deal for him.he need teeth and went to the doc as well . he was abit of a smart ass in a nice way. told the doc that when he was work in the parts washer cleaning parts . he would break out . doc told him i can cure you. all is i need abit of what makes you break out .doc told him i put some on this band aid stick it on you . before long you be fine next time dad shows up with a can of the stuff handed it to the doc sprayed on the band aid and it melted in this hands . doc said what the hell is this stuff

MEK melted my plastic lid before I could apply the cloth or resin. Keep this up and I'll try painting next.........

DC 8s were pretty much done about then---DC 10 and B747 and Convair 990 were becoming biggies with the B737 coming along in late 1968? I was in class on 37 in March 69 and a lot of the upper training people and flight management dept were starting to do dc10 and 47 stuff-----


I remember when I was still a ground mech working on a electrical problem in the dash of a food truck and got to feeling woosy---there was a open bucket/and rags under the drivers seat of tri clor-------

Fiberglass is great stuff! Whatever you can dream up is possible!!!

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Here is one of my projects from many years ago, which was intended to be marketed. Unfortunately, the bike market shifted unexpectedly before we got to market with it. The molds and some parts are for sale from my partner in the effort.

I've mocked up masters, built molds, hand laid car bodies, body parts, and done a ton of Corvette repairs and customizing, bike parts, and drag car work.

I would like to help, but my deep involvement slowed way down about 20 years ago. I am just not familiar with the chemical products available today. :-( If it is anything like paint products, they have changed radically... and not for the better.

Probably the best I can do would be to share some ideas for mocking things up. One thing I used to use was 1/4 inch hardware cloth. I used to buy it at Ace Hardware. It is like a stiff screen that could be cut and wired together, then wet cloth or mat laid over it. After you build up enough strength, the mesh can be pulled away from the inside, and the outer surface finished by skim coating with filler and block sanding. That technique, combined with finding some suitable shapes to add compound curves, could be used for almost anything.

Another thing I used regularly was a spray product that acted as a mold release. That kept the new glass from sticking to the old.

If I see something I can offer solid advise on, I'll jump in.