# Best mat to use for fiberglass sub enclosure



## Hixson

I want to glass my spare tire well in my 03 SVTFocus for weight reduction. Any ideas on the best materials to use. I have gotten alot of conflicting info on what to use.


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## bobditts

for complex curved surfaces, I like to use the matt that is easy to tear. For flatter less curvy areas, the woven mesh will work just fine. there really is no "best" matt to use, just which one is easiest for you.


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## UCF52

From what I have read; fiberglass mat (the messy stuff with the strings hanging off) is better, regardless of surface curvature, and fiberglass cloth (the neat stuff) is secondary. Again this is just what I have come across. You might want to check out fiberglassforums.com. It is a pretty good forum.


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## GlasSman

Resident fiberglass expert chimming in.....ding.... ding..... ding.

On the first initial layers you want to use chopped matt. It conforms to shapes and build up _fairly_ thick.

I say _fairly_ thick since there are other products that are superior once you have a nice solid foundation to work with.

For SUBwoofer enclosures......don't bother with the thin cloths that are readily available at most retail outlets...they don't build up thick enough.

Start with 1.5 oz chopped strand:

http://www.mertons.com/Reinforcements/chopped.html

Proceed with the additional layers using this material:

http://www.mertons.com/Reinforcements/double_stitch.html

Knytex is Super strong since it was designed to be used for structural members in large boats.

Once I start laying down the Knytex I alternate with 1.5 chopped strand to soak up the extra resin and it builds up SUPER strong.

If using proper bracing techniques you'll use 5 layers of chopped strand and 3 layers of Knhtex which will yield an enclosure thats OVERBUILT.


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## UCF52

^^ good stuff. Do you recommend using fiberglassed-laid rope, as I've seen other people do to help with bracing?


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## GlasSman

UCF52 said:


> ^^ good stuff. Do you recommend using fiberglassed-laid rope, as I've seen other people do to help with bracing?


The rope method is better for reinforcing a large flat span where a full span brace isn't practical.


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## Boostedrex

What about 1708 biaxial cloth? I've always been a fan of that. I use it as well as chop strand mat when building sub boxes. Or anything else for that matter.  But I'll be the first to admit that I'm no expert. 

And something that I wish I would've been told when I first started messing with glass. SPEND THE MONEY ON GOOD RESIN!!!!!!! It really does make a big difference!


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## GlasSman

Boostedrex said:


> What about 1708 biaxial cloth? I've always been a fan of that. I use it as well as chop strand mat when building sub boxes. Or anything else for that matter.



Thats what I meant......1708. I used the link to the chopped strand twice by accident.

Knytex *RULES!*.


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## dogstar

Can I just start out with Knytex?
I tried the chopped strand mat and I ended up with nothing but air bubbles.... it wouldn't lay down no matter what I tried.
I've got a basically useless tub that fits perfectly into my spare tire well, but isn't salvagable and I'd prefer to avoid the same problem on the rebuild.


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## robbyho

dogstar said:


> Can I just start out with Knytex?
> I tried the chopped strand mat and I ended up with nothing but air bubbles.... it wouldn't lay down no matter what I tried.
> I've got a basically useless tub that fits perfectly into my spare tire well, but isn't salvagable and I'd prefer to avoid the same problem on the rebuild.



If you can't get chop mat to lay down, then something is wrong. Just work it in until there are no bubbles.

I build up to four enclosures per day and here is some of my top secret technique. I start with 3 oz mat cut to fit each side of the enclosure. Thick mat builds very fast, but it is impossible to get it to lay down in tight corners, which is why it needs to be cut to fit. Then I'll use thin strips of 1.5 oz mat along the seams of the 3 oz mat. Two layers of 3 oz is good for small enclosures (<1 cu ft), a larger enclosure may need 3-4 layers. 

Biaxial cloth is the strongest stuff I've worked with. Two layers of that is very thin but as strong as three layers of 3 oz mat. 

Whoever commented on using quality resin had it right. If you are a noob at glassing, get a cheaper orthothalic, polyester resin like 301 from lbifiberglass.com. I'm using 901 vinylester resin from lbi with biaxial cloth on a race boat now, and the strength difference is well worth the price. For a sub enclosure it may or may not be necessary to step up from otho poly resin. The cheap stuff from a real fiberglass supplier (like uscomposites.com or lbifiberglass.com) will be 10 times better than bondo or usmarine brands.

Robby


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## Boostedrex

I always use the US Composites B-440 resin. It typically gives me up to 20 minutes of pot life on a 75-80 degree day. My neighbor still uses the bondo crap resin and he's lucky to get anything over 5 minutes of pot life with the same ambient temps.


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## GlasSman

dogstar said:


> Can I just start out with Knytex?
> I tried the chopped strand mat and I ended up with nothing but air bubbles.... it wouldn't lay down no matter what I tried.
> I've got a basically useless tub that fits perfectly into my spare tire well, but isn't salvagable and I'd prefer to avoid the same problem on the rebuild.


You CAN start with the Knytex but I like to get a nice removable and SOLID base before I start laying down the Knytex.

The chopped strand also conforms to tight spaces much better.

If you're getting air bubbles you need to use smaller more managable pieces.

Try cutting it into 8" x 3" strips to eliminate the air pockets.


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## GlasSman

Also...presoak your fiberglass on a seperate work table covered in newspaper.

You'll use just the right amount of resin and have less excess.

And if you're using a QUALITY resin you can use the excess resin sitting on the newspaper to pre-wet the next piece of material......and that process continues to the end *BEFORE* you run out of resin.....if you're using a QUALITY resin......smart....I know.


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## Tode9

GlasSman said:


> Proceed with the additional layers using this material:
> 
> http://www.mertons.com/Reinforcements/double_stitch.html
> 
> Knytex is Super strong since it was designed to be used for structural members in large boats.


How well does it cut? Does it come apart on handling?

I've been looking to use fabrics other than mat - where the application warrants - and experimented with woven roving recently. It worked really well on flat surfaces as expected and some mild, simple curves, but it would begin to unravel on cutting and handling, which was an annoyance.


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## robbyho

Tode9 said:


> How well does it cut? Does it come apart on handling?
> 
> I've been looking to use fabrics other than mat - where the application warrants - and experimented with woven roving recently. It worked really well on flat surfaces as expected and some mild, simple curves, but it would begin to unravel on cutting and handling, which was an annoyance.


I don't know about that, but biaxial cloth stays together when you cut it and doesn't fray.


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## dogstar

I wasn't trying to imply that the materials were to blame, and I'll admit I'm not terribly experienced, but I've never had problems like this before. 

I was working with hand sized pieces and "decent" resin from an actual fiberglass shop which further confuses me. It just seemed like everytime I would stipple the piece it would pop up even more. Working the bubble towards the edge of the piece just resulted in the fibers popping up, then the bubble reappeared in it's original location.
Frustrating as hell, worst glassing experience I've ever had bar none.

Maybe I'll try pre-soaking, but this project is kicking my ass so far, lol.


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## GlasSman

Tode9 said:


> How well does it cut? Does it come apart on handling?
> 
> I've been looking to use fabrics other than mat - where the application warrants - and experimented with woven roving recently. It worked really well on flat surfaces as expected and some mild, simple curves, but it would begin to unravel on cutting and handling, which was an annoyance.


Well that woven roving is a loose weave with no binders....just the long strands of fine fabric threads.

Chopped Matt has an adhesive binder that holds it all together. it is TRUELY a RANDOM pattern.


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## GlasSman

Chopped strand is made by shooting short lengths of fiberglass thread onto a wet adhesive and it's essentially rolled into it's form and trimmed.

Unraveling doesn't apply to this material.


Knytex will hold together since it is STITCHED together.....and it has a light backing layer of chopped strand on one side....at least 1708.... which I've always used does.


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## robbyho

GlasSman said:


> Knytex will hold together since it is STITCHED together.....and it has a light backing layer of chopped strand on one side....at least 1708.... which I've always used does.



that sounds exactly like biaxial...in fact it is, I just looked up what I've been using and it is:

1708 Biaxial 50"
17oz (45" x45")
/.75oz Mat 

Great stuff. I haven't used it on a speaker enclosure yet. _yet_

Do you get your stuff from lbi too? I know you are in CT.

Robby


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## Defjam

Great info!


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## Nathan P

Have any of you guys worked with epoxy resin? I much prefer it for working at home... The stuff doesn't smell at all and is easy to clean off of your hands if you get it on yourself. It's also SUPER strong, especially compared to cheap poly.

Nathan


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## HondAudio

What's wrong with using all woven mat, if you use enough of it? It seems stronger dry, and I think it would probably be stronger resined. It seems a little easier to work with anyway. I dunno I'm not an expert.


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## robbyho

HondAudio said:


> What's wrong with using all woven mat, if you use enough of it? It seems stronger dry, and I think it would probably be stronger resined. It seems a little easier to work with anyway. I dunno I'm not an expert.


There is nothing wrong with it, maybe price. For tight curves it is harder to work with. 

Just because it is stronger dry doesn't mean it is stronger once resined. For a sub box, there is no reason not to go overkill since the materials are a lot cheaper than the labor involved. 

Robby


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## iskone

Good tips.

Do you have any tips for building a structure to then use as a mold for a fiberglass enclosure? With this technique when you recommend braces a flat surface, as far as size is concerned.

For smaller enclosures such as for some mid range drivers would you only use 1 layer each?

Sorry for all the questions, LOL

I'm going to attempt to build 1.5cf boxes for each of my subs that will go in the rear corners of my crew cab Dakota, planning to have the subs pointing up and facing into the front half the cabin.


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## BoostedNihilist

If you are having an issue with a nasty airbubble just pop it.


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## machinehead

I'm gonna be doing a spare tire enclosure soon for my avalanche 15, if theres enough room. Definitely gonna over build the crap out of it. It'll be my first one.


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## GlasSman

machinehead said:


> I'm gonna be doing a spare tire enclosure soon for my avalanche 15, if theres enough room. Definitely gonna over build the crap out of it. It'll be my first one.


No need to *overbuild*.

Just build it *properly*.

Theres nothing more ironic than *HEAVY* fiberglass.


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## machinehead

GlasSman said:


> No need to *overbuild*.
> 
> Just build it *properly*.


but those are the same to me


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## GlasSman

machinehead said:


> but those are the same to me


What I'm saying if you incorporate some bracing you'll use 1/2 the resin and fiberglass material......and it will yield a stronger enclosure.

I can park a car on my braced 3/8" thick enclosures.


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## Nathan P

Nathan P said:


> Have any of you guys worked with epoxy resin? I much prefer it for working at home... The stuff doesn't smell at all and is easy to clean off of your hands if you get it on yourself. It's also SUPER strong, especially compared to cheap poly.
> 
> Nathan


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## Hixson

Glassman, have you worked with carbon fiber? I ask because a friend of mine works for an IRL team and gave me a pile of scrap pieces for a case of beer. I have one large piece and a bunch of squares and scrap. Wondering what the best resin to use? A brand is what I'm looking for. I was told to stick with the epoxy resin for CF.


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## GlasSman

You want to use an epoxy resin.


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## jtroy

Nathan P said:


>




Epoxy is great stuff but cant really justify the extra cost......also avoid using acetone with epoxy


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## Hixson

So poly or epoxy will work but epoxy is preffered?


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## GlasSman

Hixson said:


> So poly or epoxy will work but epoxy is preffered?


A BIG.....*NO!*

You *MUST* use epoxy resin with carbon fiber.


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## Hixson

I went to AVT Composites in Indy and they helped me out big time! Got everything I need to do the job. Starting Thursday morning and taling pics


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## GlasSman

Hixson said:


> I went to AVT Composites in Indy and they helped me out big time! Got everything I need to do the job. Starting Thursday morning and taling pics


Which Epoxy resin did you get?


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## SQ4ME2

i agree i use 3/4 oz to start for vertical points and then step up to 1.5 oz for most of the rest of it. getting out the bubbles is key and heavier ounce in bigger sections is good but the other works well


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## BlackSapphire

Nathan P said:


> Have any of you guys worked with epoxy resin? I much prefer it for working at home... The stuff doesn't smell at all and is easy to clean off of your hands if you get it on yourself. It's also SUPER strong, especially compared to cheap poly.
> 
> Nathan


Keep in mind that you can't use epoxy resin with fiberglass mat.


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## SQ4ME2

Hixson said:


> I want to glass my spare tire well in my 03 SVTFocus for weight reduction. Any ideas on the best materials to use. I have gotten alot of conflicting info on what to use.



i use 1.5 to 2 ounce and i cut it into strips first and spray glue it in place and that usually makes for a good mold. then build it up with torn pieces or squares


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