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Old 06-19-2009, 06:52 PM
Nic Nic is offline
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Default Fiberglassing tips and tricks

Fiberglassing tips and tricks

Fiberglass resin does not stick very well to tin foil or plastic wrap. I have used both of these as a separating agent if I am making a mold of something.

PVA and carnuba wax in combination is a better idea. Apply at least 5 layers of wax to the surface(s) of whatever you are going to copy. Apply several thin coats of PVA to the waxed surfaces. A cheap spray gun can be picked up anywhere, harbor freight.

Chip brushes - If you cut the bristles so that they are about 1/2" to 3/4" long, it helps to push the mat into the resin.

Fiberglass Roller - GET ONE! If you want to have as little trouble as possible with air bubbles and de-lamination, rollers are your FRIEND. My opinion, get one of these barrel rollers and if you think you'll be doing inside corners, a corner roller too.
Barrel & Corner Rollers: TAP Plastics

Resin brands - repeat after me. Say NO to Bondo!!! Their resin has wax in it, which must be sanded down between layers. Compared to other resins, is not as nice to work with, it is very thick and does not wet out fiberglass very easily. Nearly any other brands of resin will be fine, however these are recommended.
US Composites - B440
TAP Plastics Structural Lay-up Resin (Yellow container) <- this is what I use.
Fiberglast.com #77 Polyester Molding Resin

Resin hand pump - Good idea. Most dispense 1 CC of fluid at a time.

MEKP Methyl Ethyl Ketone Peroxide - This is the hardening agent for resin and gel coat. Use whatever comes with the resin or what ever the vendor sells.

Styrene Monomer
- To be used as a resin and gel coat thinner. Do not use acetone.


Chop stand mat (CSM) Prep.
- If you are going to be glassing a large section of something that has any curve to it, do yourself a BIG favor and rip your mat into smaller manageable sections. 4x4 or 6x6 squares are best. When you lay them down, overlap the torn edges. Doing this allows the chop mat to conform to contours better than 1 large piece of CSM.

Applying CSM to sharp corners or curves - IF you aren't making a mold of something or if you wont be removing the fiberglass after it's applied you can try this. A very light coat of spray glue on what ever surface you are glassing to will hold the mat in place while you are applying resin.

If you are going to be removing it, try this. Prepare all of your CSM or whatever first. Theh, mix a hot batch of resin, say... 10 - 12 drops of mekp per cc of resin. Paint it on to your surface. Depending on ambient temperature, 80 and above, it may begin to kick within 5 -10 minutes. Once it starts to kick and is sticky, apply your mat. This will hold it in place for your next go around with resin.


Floral Foam - If you are going to make a custom part that will need to be formed or carved, but not it great detail, floral foam is your buddy. You can find it at Joann fabrics pretty easily and some craft stores. If they sell silk flowers, they probably sell this too. Floral foam cuts and sands VERY easily. I use a hack saw to get rough shapes, then 80 grit sand paper to do the rest. You need to have a light hand when sanding this though, it comes off real easy. Once you have your desired shape, start glassing. You can fiber glass right over the top of it. However you will have to dig out the foam when you are done.

Foam in a can
- This stuff can be useful as well but there are a few things to be aware of.
1. You cannot glass right over this stuff, the resin will eat the foam.
2. It does not expand uniformly, you will have to over-fill and cut/sand back to the shape you want.
3. It doesn't cut or sand and nicely as floral foam.
4. If you get it on your skin, its a pain to get off. Grab the replacetone. If you get it on your clothes, buy new clothes.

2 part expanding foam - This you can glass right over. It is sold in a Part A and Part B configuration. Mix equal parts and pour. Stand back. It sands easier than foam in a can, but still not as good as floral foam.


Thats all for now. Possibly more to come later.Thanks for reading.
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Old 08-02-2009, 06:20 PM
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Is there a cheaper alternative to buying some exotic release compound? The stuff we use in the navy looks lke crisco, but cost about 600 a gallon.

Some people have mentioned pam non stick cooking spray. The only other method we use in the navy is bagging film AKA peel ply. its plastic that doesnt adhere to resin. great stuff, reusable, but not cheap.
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Old 08-02-2009, 10:58 PM
Nic Nic is offline
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Do you mean cheaper than PVA? PVA isn't all that expensive. However, any good carnuba wax also works as a mold release. However... you need to apply at least 6-8 coats of wax to make a good releasable surface. Lately I've been using tin foil to act as a barrier between parts. Works fairly well, and is cheap.
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Old 08-02-2009, 11:54 PM
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he he, never thought of turtle wax. LOL I bet the tin foils a pain to get off the cured resin!
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Old 08-03-2009, 12:06 PM
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If you can manage to keep the foil flat, it peels right off. However if you have a ridges in the foil, yes, the resin seeps in under and locks the foil in, then you have to dig it out with a razor blade and tweezers if your lucky.
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Old 10-06-2009, 12:13 AM
Nic Nic is offline
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I wanted to add a few more things here.

1. Get to know how the different weights ( 1.5oz and .75 oz) of mat behave when wet out with resin. Lighter CSM will conform to curves better than the heavier 1.5 oz will. You can obviously layer 2 layers of .75 to get the same thickness as 1.5.

2. Woven cloth will make curves, but not compound curves. It doesn't like to be pulled in too many directions. So if you are making a tube, woven cloth is just as capable as CSM. However I do think CSM will be stronger in the end due to the random orientation of fibers.

3. Be careful how much resin you use. You don't want to use too little and you don't want to use too much. You can tell after the fact how well you did. If you see areas that are darker than others... too much resin. If you see areas that appear white, that means there was not enough resin to wet out the mat, and it's still dry.
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Old 10-06-2009, 12:28 AM
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Nic,

Have you played with vacuum bagging your projects? This is the method used by the military one F18's. I forces the plys together with atmospheric pressure. This squeezes out any excess resin and makes your bond damn near hard a steel.
I use a vacuum pump designed for pulling a vacuum on A/C systems, they are about 10 buck on ebay.
Then you make a block of wood or aluminum with a hose fitting on it, and some breather holes under it.
Add you bagging film, and the air pressure drops down on it like a large uniform weight.
Probably over kill for a car project, but it works really well. And the structures can be thinner, lighter, yet stronger.

Vacuum Bagging: Basics - Composite Materials

Basic Vacuum Bagging

Last edited by ydeardorff; 10-06-2009 at 12:31 AM.
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Old 10-06-2009, 11:17 AM
Nic Nic is offline
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I haven't done any vac bagging yet. However since you have, you should do a write up here about it. You probably have the most experience with it.
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Old 09-24-2011, 12:16 PM
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you guys ever thought about buying some mold release and use gel coat.

i buy everything from fantastic plastics in kcmo

dale
ps modeling clay over any type works wonders
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Old 09-24-2011, 07:08 PM
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You get the best results from gel coat when its applied to a mold and for most of the guys here, making a mold for a one run off part is not worth the cost and time. You can spray gel coat over the finished part and then sand and polish it but the finish wont be as nice as it would be if the part was pulled from a mold, and the gel coat thickness will vary from the sanding so most of the guys here(right me if I'm wrong)end up just painting the part or parts which produces a nice gloss finish and a few layers of clear coat really make it shine and last.

Brett
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