Fiberglass Tips & Tricks for Beginners

I'm very new at this, looking for all the help I can get.  I've figured out the basics, but would really appreciate all the tips & tricks y'all have picked up thru experience that would make my life easier on the next few projects.

This started on another thread, I'm going to migrate those posts here.  Feel free to add anything you'd tell a beginner, the sort of thing you wish someone had told you...

Poormanq45 wrote:

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The thing I like best about mat is that even if it folds over on itself that you can just add a bit more resin and stab it down. YOu can't do that with the weave stuff.

Try my method of applying resin first then sticking the mat to that. You'll probably find it alot easier to work with sinse you won't have to hold it in place while you apply resin.

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Steven Kephart wrote:

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Poormanq45 wrote:

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I just glassed right onto the tape.

First I like to apply the resin, then stick the mat to that then stab more resin into it. I think I did like 3 layers before I took it out of the trunk. Then I just kept adding layers until it passed the thumb test. Some areas took like 10 layers, others were good with 4 layers.

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Wow, 10 layers?  I normally don't go above 5-6 layers of 1.5 oz mat.  One suggestion is to add ribs on the flat areas to give it strength.  I did this on my dash mold by taping down pieces of 16 awg wire like a # sign and fiberglassing over it.  This produced ribs in the mold that added strength.  Or on a larger project I made them out of wood and fiberglassed them in.   This technique should save you some money on fiberglass materials. 

Steven Kephart

Adire Audio

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A couple questions -

Using the correct amount of MEKP to resin gives me a working time of about 4 minutes before I get clumps.  Partly due to dry Colorado air, I'm sure.  How can I stretch that time?  I'm thinking less MEKP, but not sure it will cure properly.

Next - now that I have sanded resin particles in a couple places on my skin itching like mad, how can I get it off?  Does it just go away?  Showering helped, but not completely.

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boulderguy wrote:

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A couple questions -

Using the correct amount of MEKP to resin gives me a working time of about 4 minutes before I get clumps.  Partly due to dry Colorado air, I'm sure.  How can I stretch that time?  I'm thinking less MEKP, but not sure it will cure properly.

Next - now that I have sanded resin particles in a couple places on my skin itching like mad, how can I get it off?  Does it just go away?  Showering helped, but not completely.

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1.  Definitely less MEKP. 

2.  I've found that imediately following any sanding on fiberglass that washing with hot water too hot to stand for more than half a second works.  Keep it under as long as possible without burning yourself, and wash twice.  This opens up the pores and washes away the particles.  And of course, wear rubber gloves and long sleeves if possible.

Steven Kephart

Adire Audio

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Here's some other tips I've picked up along the way.

Cut your brush down to 1" long bristles.  This will allow you to push the air bubbles out better.

Apply a layer of resin to the surface you are about to fiberglass before you lay down your mat.  This will allow the mat to stick in place and not move around on you.  It will also soak up with resin faster.

Tear all the edges of your mat instead of cutting with scissors.  This will allow two pieces of mat to meld together much more smoothly providing a more even surface when done. 

Prepare your mat ahead of time before mixing up the resin.  Lay down the number of layers you want to apply with the batch of resin, then set them aside so they are handy.

One thing I prefer to do when suspending rings is to use backstrap and hot glue.  It holds them in place very nicely, doesn't get in the way of your fiberglassing project, and you can remove them when done. 

For smaller projects, go down to the local Michaels, or other floral store and buy some green foam used to make floral arrangements (it's pretty cheap).  You can glue these foam bricks together, then carve out the shape that you want.  I like to use a long break-away utility knife and sand paper for the forming of my piece.  Then when the shape is carved, just fiberglass over the foam (the fiberglassing won't effect the foams shape) and then use some solvent or gasoline to eat away the foam on the inside.  Now you have a perfect fiberglass mold.

I'll try to add more tips later if I can think of them.

Steven Kephart

Adire Audio

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Steven: COuldn't you leave the foam in place to act kind of like polyfil and/or a sound deadning?

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Poormanq45:

It's too thick to work well as polyfill, and probably too light to work as deadening.  But I wasn't really talking about using it for sub enclosures as it would take a LOT of it to do.   Although you could probably use it to provide a form to stretch to in a sub enclosure if you are going for some crazy design.   But I was more thinking of for small objects like what I am working on right now.  I'm building a piece to hold my faceplate, and lighting switches that will mount right in front of my subwoofer on the console.  I will try to get some pics up when I have a chance, which should give you an idea of what I am talking about.

Steven Kephart

Adire Audio 

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I thought of one other tip to add when fiberglassing.  Try to prep the mat previous to mixing the resin by laying down as many layers as you plan on doing with that batch.  But when you do this, make sure the mat lays down flat.  If you have any curves, make sure it doesn't double over on it'self.  Tear out that piece if you have to so it lays flat.  Also in some convex areas you may have to tear the mat to lay down flat, and apply a small piece of mat in the bald area created by that tear.  I hope that made sense.

Steven Kephart

Adire Audio 

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Concerning the shower thing, that is 50/50... I'd take a cold shower first to get the good majority off of the body period and not risk getting into the pores. Then take a hot enough one to open them up and get some crap out. I feel the heat thing could be bad for people that are less tolerant to hear(ME). My 2 cents. The rest of his spew, well, I will back that all. I coulda used it BEFORE I started my training projects, but I got them at some point. :) Thanks. Ya know I love ya Steven.

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1998 Monte Carlo w/
Eclipse CD8454
2xRockford 5.25" Power 2-way T152C
2xRockford 6"x9" Punch 3-way FRC4369
1xMemphis 16-MCH1300 5-channel
2xKicker 12" L5 Solobaric-2 Ohm

as far as im concerned the most important thing is to not cheap out on the resin. the only time i have ever had a problem with glassing was when i first started, and i was trying to put small amounts of resin on at a time to try to keep from using too much. now i just pour it on and stipple it in. That works mint for me, and as long as you dont use too much, the mat will stay in place.

and also what you might like to remember is to keep the mat from bunching up, try to keep it flat.

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2000 Chevrolet S10
Premier DEH-P860MP
JL Audio XR650-CSi components
Boston 4x6 splits
JL Audio 10W3v2
Alpine MRP-M350
Clarion APA-4162

Migrating another good posting...

Steven Kephart wrote:

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I'd recommend more time spent on the body filler stage.  The surface doesn't look to be very smooth having those bumps in it.  What I recommend is using 36 grit paper till it's perfect.  You can use a palm sander, but I find that doing it by hand for the last bit just seems to work better as you have so much more control.  Anyway, durring the body filler step, you might not see those valleys and hills.  But they will show up once you paint them.  I find that the best way to find them is by closing my eyes, and running my hand over the surface.  You can feel them and know where you need to build up or take down more.  Once you have the shape perfect, then use 110 grit to get rid of any sanding marks, primer, then use 220 to sand that smooth.  A light mist of black spray paint on the primer will help you see where any remaining surface flaws are.  At least these are the tips that I've learned. 

Also, as a tip to get that snugger fit like what DukeDuke says, try taping off the area around the enclosures edge, and mixing up some fiberglass reinforced body filler like Duraglass.  Now apply it to the edge of the enclosure, making sure it fills all the way to the taped off carpet.  Do this with the whole enclosure and you will end up with something that molds perfectly in the vehicle.  Here's a picture of a couple projects where I did this:

That last picture I learned the hard way that Rage Gold doesn't work well in thin areas (you can see the chips).  That's why I suggest, and use Duraglass for thinner edge work.

Please forgive me if I am being overly critical.  But the people who you want to buy those pieces will be even more critical, and putting your best foot forward is always well worth it if you are planning on selling more of these.  Otherwise you are doing a fantastic job.

Steven Kephart

Adire Audio

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Here's one more from Steven Kephart -

I had a mold with too little MEKP, wasn't hardening.  Opted to spread MEKP directly over the surface.  His reply -

"I would be very careful about adding MEKP to the surface like that.  Having too little hardener has the effect of it taking longer to harden.  Having too much hardener can cause fires.  I’ve mixed too much hardener before and I can assure you it gets REALLY hot.  You can boil water with it, and even break rocks in half.  Having it on a flammable surface like carpet can cause it to start melting and even igniting which isn’t a good thing. "

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Picking thru some older posts, here's some good info.  I'm migrating other's posts here, so if anyone feels like I'm "plagerizing," let me know & I'll pull your post down.

Steven Kephart wrote:

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I personally prefer grill cloth as it doesn't soak up nearly as much resin.  This layer is purely to supply a surface to apply the fiberglass on, so all the extra resin is wasted IMO.  I've tried it once and will never use it again for that reason.

Fleece is not nearly as strong as fiberglass mat/cloth.  It is not intended to be a structural layer, but a surface to lay down your structural layers.  And sure it may be a little cheaper than grill cloth, but considering it takes 3-4 times the resin, grill cloth becomes the cost effective solution real fast.  I'd much rather have the enclosure that weighs less (less resin/thinner walls) and is just as strong.

Steven Kephart

Adire Audio

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Poormanq45 wrote:

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Again I'm with steven on this one.

EVen though the fleece costs less then the grill cloth, the amount of resin that it soaks up brings the total cost to MORE then it would cost for the grill cloth.

Also, the fleece layer is only a base layer. Its only purpose is to give you something to build on.

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Painting & priming + sanding

audiomechanic wrote:

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this was also posted in another thread, but i figure this might be easier to spot in a search.

ok, there seems to be a little bit of confusion about painting here. I am not gonna try and say that the projects you guys are doing are not turning out good (I have never seen any of them). What I will say, is that some of the things you guys are doing are not correct or condoned by the paint manufacturers, and can shorten the life of the paint job or cause problems.

first i will start with fillers and sanding:

most of your filler sanding can be done with 36 or 40 grit. there is no need to go higher than 80 grit. Most of the filler or sanding primers will fill in the sanding scratches. Body fillers are used to smooth out low spots and make things as "flat" as possible. By "flat" i mean no waves in the piece. As a rule use the filler approperiate for the situation;
long hair fiberglass filler- 1/2-1/4 inch deep
short hair fiberglass filler- 1/4-1/8 inch deep
body filler- 1/8 or less
spot filler(2K glazing putty)- pin holes or very minor imperfections

Primers:

after you are satisfied with the way it looks and are sure you got out all the major flaws, it is time for the Polyester primer. It takes MEKP as the hardener just like resin does. some brands sand easier than others. I use Featherfill G2 by Evercoat. A few of the other brands i have used with good results are Omni MX245, Duratec, and Sherwin Williams 21. Apply 2-3 coats over areas with filler and 2-3 coats over the entire project for a total of 4-6 coats using a 2.0mm tip. After the poly primer cures (1-3 hours), spray a guide coat. This can be any contrasting color. some people use a light coat of black spray paint, but 3M and others sell guide coat in a can. sand it with 180 grit. USE A SANDING BLOCK or a DA. Never sand without something between your fingers and the sandpaper. It can and most of the time will leave little low spots from your finger tips and/ or palm. Sand the poly primer to 400-600 grit making sure to get rid of all the sanding scratches from the previous grit. If you break through the poly primer dont worry. Once you are at 400-600 grit, of there are large area where the filler is showing, spray a couple more light coats of primer on those spots. If there are just a couple small patches, don't worry about it. If there are any imperfections such as cracks, deep scratches, pin holes, fabric showing through or anything at all, FIX IT NOW. it is your last chance. If all is good, mix up a 2K sealer primer. this give an even color and surface for the base coat (color) to adhere to. sealer should not be sanded unless it is to remove dirt or other things in the primer. if you need to sand it, look at the can to make sure you do not need apply another coat. all you are looking for is even coverage, not thick filling coats like the other primers. most sealers need to sit for at least 1-2 hours before the color can be applied. if left longer than 24 hours, they need to be scuffed and another coat needs to be applied for maximum adhesion.

Base (Color) coat:
get the color code from the car and have the paint mixed to match. Because of the fade some cars have it is wise to shoot a test piece to make sure the paint match is pretty close. if not it can be altered(tinted) at the paint store. Using a 1.3 -1.5mm tip in your gun spray thin coats. depending on the sealer used it may take a few to get an even color over the entire piece(s). usually it takes 2-3 coats for even coverage waithin at least 10 minutes between coats. If there is any dirt in the base color, wet sand with 600-800 grit then reapply the base. This is recommended by ALL the paint manufacturers!!!! once an even color is achieved, let it sit for at least 1 hour before applying the clear. mose base colors can sit for a few days with out top coating. if they sit longer than recommended, there might be an issue with the clear not sticking to the color.

Clear coat:
This is the step that brings out the shine and true color of the base coat. It is also will also show any imperfections that you may not have caught before. at this point if you have a pinhole you missed or sanding scratches, you are stuck with them unless you want so sand back through all of the clear and base to fix them. Use the a slower reducer to help the clear flatten or lay down. the downside to using a slower reducer is that the flash time is a little longer between coats and has a little more time to collect dust and other stuff in the air. but the benifit is there is less orange peel.
Spray the clear coat with a 1.2-1.5mm tip (i use a 1.3mm). It works good to apply a lighter layer as a tack coat let it sit for about 10 minutes then shoot on 2-3 medium-heavy wet coats waiting about 10-15 minutes in between coats. when the clear is ready for the next coat, you should be able to touch it and not have it stringy when you remove your finger. make sure you touch an area that will NOT be seen. once you have applied all the coats of clear let it sit over night (12 hours).

Wetsanding:
sand with 1500 or 2000 grit using a DA or sanding block and sand paper. make sure the entire surface is dull (no shiny spots). using a buffing machine, foam pad, and compound, buff it out. start with a rubbing compound, then machine glaze. use a different foam pad for each different compound. dont turn the machine up too fast or you will burn throught the clear (1500-1800 rpms).   

I hope that cleared up some things and will get you practicing with a more accurate picture of the process in your mind.

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And an entire thread on release agents -

https://www.the12volt.com/installbay/forum_posts.asp?tid=58863&PN=2

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as far as the FG itching your skin after sanding, yeah, that will happen, if long sleeves are not comfortable, or you just wont wear them, then try using a fine talc powder on your skin liberally before you sand.  Dont wipe it off until you are done.  this will absorbe the sweat or moisture on your skin that the fiberglass dist sticks to.  This will greatly reduce the itching!

as far as the itchy feeling from the FG dust, i agree, gloves and long sleeves, but also use a talc powder on your skin that may be exposed to the dust.  apply it liberally, and leave it on until you are done.  The FG dust normally sticks to your skin if you are sweating, or if there is moisture on your skin, and then gets into your pores.  If you use the talc, it will absorb the moisture, and prevent the FG from sticking to you!

sorry about the double post, i got an error message, it said that it did not post, so I re-posted... oops!