What do i need to do some fiberglassing?

h0oligan

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Jan 18, 2003
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i was thinking about trying to make my own custom box for 2 12" inch subs with fiberglass. Does anyone know anything about this? What supplies do i need and where could i get them? I saw a guy do it on Monster Garage and it looks pretty easy.
 
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Well, you need the resin and hardener and some fiberglass cloth or mat (or both). Then you need a bunch of cheap disposable brushes to apply the resin, some latex gloves (not completely necessary, but a good idea), some fleece (t shirt material) if you want, as you can use it to build up a thick layer quickly, and a mixing bowl that you don't want for any other use. Also, a lot of masking tape or duct tape, and some kind of mold release. Pam cooking spray actually works well for this.

You can get the resin and hardener as well as the cloth at Home Depot, Lowe's, or most auto stores like Autozone. You can probably get it at a marine supply store as well. If you have a Harbor Freight around you, they sell boxes of brushes really cheap.

If you're doing a sub box, you'll also need wood to make mounting rings and probably some wooden dowels to help get everything positioned the way you want it.

Keep in mind that fiberglass is strongest in curves, so if you have a big flat section, it'd be better to use wood for that part. It's not the hardest stuff to use, but it can be difficult to use well, ya know?

If you decide to do it, make sure you're in a well ventilated area, as the fumes aren't the best for your health (you can use a respirator if you want or need to). Your car will probably stink for a few days after you make the initial mold in the car. Then when you get to the point of finishing it, get ready for seemingly endless sanding...
 
I asked a guy at home depot and he said they didnt have anything i needed. I'll try the autoparts store.

The guy on Monster Garage had this foam that he used as a mold, do you know what kind of foam that was? He shaped it into the shape he wanted and then fiberglassed right over it, that's what i was planning on doing.
 
You don't really need a mold to use fiberglass, but the mold is usually foam that can be dissolved when finished, can't remember which type, exactly.
For the basic fiberglass box, you can get anything you need at Wal-Mart or a boating supply store will definetly have it.
Here's a site to give you an idea: http://web.njit.edu/~cas1383/glassing2/ http://ecominet2.alpine-usa.com/html/adc/adc_install1.html?par=p1c1
If you have ANY questions, these are the guys to ask: http://www.fibreglast.com/phpBB2/index.php
 
I need to know what that foam block was made out of so I can get the shape i want. BTW I found everything else i need at Autozone. The fiberglass is gonna be more for looks than the box itself for the subs.
 
Haven't seen the episode of Monster Garage yet, but Tivo got it, so i'll watch it soon. I've read on some other forums about the guy doing some glass work, and he most likely used a 2 part expanding foam, then shaped/sanded it to the form he was after. Foam blocks, like you mention, are often floral foam, which is available at most crafts or flower shops. Be careful, if you dont mask the foam, many types will be immediately dissolved by the fiberglass resin (or sometimes even just the fumes!).

It may look easy, and it's definitely not rocket science, but expect some trial and error especially if you haven't worked with FG before. After all, if it was so simple, wouldn't all of us have tricked out installs and not a bunch of carpeted boxes made of mdf?

Joker's tips are on the money. Only thing I would change would be to definitely buy a box of gloves. He's right, its not necessary, but you'll be glad you did. Get a good glob on your arm hair and you'll understand what i mean.

Good luck on your project, and I'll be happy to help if you have other questions regarding materials/techniques.

Alan
 
I'm about to try my hand at glassing my woofers into my doors so it doesn't look ugly like it currently does, also going to be doing molds for my tweeters on the top of the door... this thread helps a lot. Thanks.
 
I'm thinking (although I haven't seen the Monster Garage episode) that you could probably do something similar with expanding insulation foam. Home Depot usually has it in those spray cans. I guess you could spray some of it down, let it puff up and dry some, then carve out the mold you want. If you do this in the car or on a car part though, you'd better be damn sure you cover the part up well so the foam doesn't stick to the actual part. That foam can be pretty tough to get back off.
 
I want to know what kind of foam block I can use because i need to work on a big scale with a lot of curves, so i want to be able to form that foam block exactly how i want it. I'm looking for something like a 3x2x2 feet block. I wish one of you had seen that episode, then you would know exactly what i am talking about.
 
h0oligan said:
I want to know what kind of foam block I can use because i need to work on a big scale with a lot of curves, so i want to be able to form that foam block exactly how i want it. I'm looking for something like a 3x2x2 feet block. I wish one of you had seen that episode, then you would know exactly what i am talking about.


Is it the episode where they turn the boat into a car??
 
Cloth has all the fibers woven together, and it stays together like a thin sheet of fabric. Mat, on the other hand, has all the fibers more or less just pressed together, and is much stiffer while dry than cloth is. The mat is thicker, however, and will build up layers faster than the cloth. One downside is that when you cut the mat to get it into manageable pieces, it sheds a crapload of those raw fibers everywhere.

Usually, the cloth is better for the first layer or two, when you really need to mold the form to the contours of what you're working on, then as you progress, you can use the cloth to add thickness and strength.
 
I realize that this thread is old as dirt, but a question was never answered, and it seems to come up every once in a while.

The expanding foam that will not dissolve in Polyester resin is Polyurethane. What you don't want to use is styrofoam (any thing that says Styrene), because it will dissolve.
Polyurethane foam can be purchased in blocks that you can carve to the desired shape, or as the expanding foams (usually marketed as home insulation products).
Styrofoam will be dissolved by the Stryrene monomer in the Polyester resin. If I remember right Vinyl Ester resins will dissolve styrene as well, but double check that before making a purchase. I don't remember if there is styrene monomer in the vinyl ester or not.

Epoxy resin will not dissolve either of these foams.

fyi
jason