Sealing, smoothing FG and MDF

So, I've been working on a fiberglass/MDF enclosure, that I can remove and re-insert If i ever need the spare tire or more trunk-space, for two 10" subwoofers. So far I have only come along one thing that I'm really unsure and curious about. In the area on the edges of the fiberglass (Shown more clearly in the pictures.) Im worried that it wont be correctly sealed between that and the MDF. Should I extend the fiberglass over farther to touch the MDF, should I put a bead of silicon sealant all around between the FG and MDF (Something that I thought about, that I thought may work.) , or should I just leave it alone. Im just a little worried about it being incorrectly sealed. No big deal.

Any help is greatly appreciated. Thanks alot!  :)

Andy

https://i11.photobucket.com/albums/a195/andyplacenta/fiberglassed.jpg

It's my first time making a subwoofer enclosure, let alone one with fiberglass. Pretty good so far huh?

https://i11.photobucket.com/albums/a195/andyplacenta/MDFtoFG.jpg

This is the area where I want to make sure to seal up. 

Oops, for those who dont feel like clicking the links above...  heh...

It's my first time making a subwoofer enclosure, let alone one with fiberglass. Pretty good so far huh?

This is the area where I want to make sure to seal up. 

Should I put just the resin/hardener/talcom powder on the joints of the inside, or is the fiberglass mat really needed? Oh, and how many times is it recommended to repeat the process of adding body filler and sanding it?

Make about a quart or so(depending on the total size of the enclosure) and mix it with talc and 1/4" chop strand.  Make it like a runny oatmeal consistency and pour it in the enclosure, slowly 'swirl' it around in the enclosure making sure to concentrate it on the edges where you want your seal,,,this will totally seal the box and add strength to the box.  I do this on every enclosure I build the step after the resin has kicked or hardened on the fleece...Perfect seal with no silicones or foreign substances,,,

whosandy wrote:

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Alright Ctoh, I like that idea. Sounds like it will work really well. Two things though, chop strand... when I've been at HomeDepot and other stores like that, I havent seen any chop strand. Only mat and cloth. Should I go to a boat store instead? Also, I already put some silicon along the inside to seal it. Do you think it would still be good to put the mixture your talking about into the enclosure over top, or would that just be unnesessary and redundant?

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You probably won't find strand at a place like that, check www.uscomposites.com and see if they have it, you won't need a whole lot.  I buy it in 50 lb bags, if you can't find it, PM me your address and I'll send you a big Ziploc bag full of it.  I'd remove the silicone if I were you...Do you have Talc also?  I buy that in 50 lb bags as well,,,You don't do this step outside of the box, only on the inside if that is what you are meaning by 'over the top' but do remove the silicone for the resin to not have any inhibitors inside,,,

whosandy wrote:

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Alright Ctoh, I like that idea. Sounds like it will work really well. Two things though, chop strand... when I've been at HomeDepot and other stores like that, I havent seen any chop strand. Only mat and cloth. Should I go to a boat store instead? Also, I already put some silicon along the inside to seal it. Do you think it would still be good to put the mixture your talking about into the enclosure over top, or would that just be unnesessary and redundant?

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You probably won't find strand at a place like that, check www.uscomposites.com and see if they have it, you won't need a whole lot.  I buy it in 50 lb bags, if you can't find it, PM me your address and I'll send you a big Ziploc bag full of it.  I'd remove the silicone if I were you...Do you have Talc also?  I buy that in 50 lb bags as well,,,You don't do this step outside of the box, only on the inside if that is what you are meaning by 'over the top' but do remove the silicone for the resin to not have any inhibitors inside,,,

CTOH] wrote:

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You probably won't find strand at a place like that, check www.uscomposites.com and see if they have it, you won't need a whole lot.  I buy it in 50 lb bags, if you can't find it, PM me your address and I'll send you a big Ziploc bag full of it.  I'd remove the silicone if I were you...Do you have Talc also?  I buy that in 50 lb bags as well,,,You don't do this step outside of the box, only on the inside if that is what you are meaning by 'over the top' but do remove the silicone for the resin to not have any inhibitors inside,,,

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This is my first fiberglass project. I was wondering if anybody can help me with smoothing out the Fiberglass to be somewhat flush to the MDF on the elges. I was told I could cut off the excess fabric and use Bondo or body-filler to flatten it out. If anybody has any other ideas, or ideas that could be better, I would really appreciate the feedback.

Thanks,

Andy

The enclosure and its rough edges. ^^

Close up on those edges. ^^

Can you grind/sand the edges off? (the rest of the glass is adhered to the box?) 

By looking at the pic you would have to glass the sides to the same thickness to smooth it out.

gavin9797 wrote:

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Can you grind/sand the edges off? (the rest of the glass is adhered to the box?) 

By looking at the pic you would have to glass the sides to the same thickness to smooth it out.

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I could grind the edges off, but I would be affraid that the fiberglass would not be well enough attached to the rest of the box itself if i grinded it off, because the staples for the fleece I had used were placed on the sides that I show in the picture. Does that sound sensible enough? Well, unless the resin had seeped into the wood enough to really end up attaching the fiberglass front well enough, I dont think it would stay strongly attached. I could glass the sides too, but im just planning to lay some carpet over the sides anyways, because I only wanted the part that I originally fiberglassed to be the part that I would later end up painting, or getting pained. So, im affraid that fiberglassing the sides too would be a waste of time and money.

Any other ideas?

on the strands . just take some fiberglass matt and use a fork or some other pointed tool to separate the strands. simple as pie. and you could cut off the the excess and layer some more fiberglass across the front and sides. cause the fleece alone wont be strong enough you'll need several layers. and dsbenjamin, we call that kitty hair or kat hair. its basically harder bondo w/ strands of fiberglass in it. it is just as thick if not thicker than bondo and way stronger. you could use this on the inside for the strength. but it is so hard to sand, somewhat like concrete, its not good to use on the ouside unless you want to build an area up. But if you cut the loose fleece of and relayer with fiberglass like half way over the mdf it should be more than enough