sparkie124

I have a sub box that is mdf and carpeted. I am wanting to glass it to protect the mdf from moisture. It will go under the back seat. How should i go about doing this. Can i just put the resin over the carpet(use carpet as the mat) and then sand it down or should i remove the carpet- if i remove the carpet will i use mat or just resin on the mdf. Any ideas.

Fenderjack

iTrader: (2)

You prob could go over the carpet, but that would be a ton of res to soak into it to the point of it being built up enough to sand smooth, also some of the carpets I have seen have some type of oil in them, so not sure how well it will actually stick to it. I would pull the carpet off, sand the box down, round the edges, corners if you like, just seal it up using res.. Just mix it up thick..


John jr

Rookie

iTrader: (4)

We always coated the inside and outside of our sub boxes with resin when we made them years ago. And then carpeted over them. It always seem to give you that extra something.

hadleycat

I would definitely take the carpet off before putting the resin on. If not you will need about 5 gallons of resin and you will have a total mess on your hands. I would coat the bare mdf with resin then glue the carpet back on. If you use staples they will break through the resin barrier you just created and allow moisture into the mdf.

hadleycat

I dont think mat is necessary for this project. Mdf is very absorbent and should hold the resin well. Coating the inside as well would be nice but if the box is already built this probably isnt an option, and you should be fine without it

glassdave

iTrader: (1)

resin alone would be ok but have a limited and much shorter life then tossing on some mat. The problem is as the wood cycles through temps it expands and contracts fracturing the unsupported resin and that will eventually lead to delamination of the mdf allowing moisture in to cause further damage. Pull the carpet, toss on a layer of mat inside and out an crank up the tunes this summer



Traditionally a lot of these automotive type enclosures dont live well in the marine environment but you can hedge your bet with some well placed products

hotjava66

Related question, would it be better to use a marine plywood instead of mdf? I need to redo the mounting board for my subs, the one that is in my boat now is getting rough after only a couple years but it wasnt resin coated. Glassdave, what is the products you would use to coat it since I know little about glass?

glassdave

iTrader: (1)

yes very much better then mdf. For just a simple and durable surface coat use this stuff.

http://uscomposites.com/polyesters.html

http://uscomposites.com/mat.html

http://uscomposites.com/solvents.html


435 GP poly (SM-435***) would be fine with 1.5oz chop strand mat. After its cured do a final coat of just resin or gelcoat with some surfacing waxing in it to get rid of the tackiness. Also dont forget to put a nice radius on all the wood corners to allow the glass to make the bend easier.

J-Bonz

iTrader: (3)

I was curious to see what you would type.... I still have to build boxs for my two subs....

4bus

iTrader: (4)

The reason MDF is used for speakers (even the big dollar companys use it ) is sound quality. Ply is never a good choice for sound, however if you must use ply I would recommend a sealed enclosure with poly filling to soften the kettle drum sound you will get from a soild wood.

The last box I made I used a thin fleece from Jo-ann fabics. Resin coated about 6 times. thin layer of bondo over resin, block sanded, had painted candy and cleared at local body shop. Took about 3 weeks from start to finish, and I would never do it again.

I have built a few mdf boxes with marine starboard fronts. The front of the box was also the back seat base of the boat. They looked and sounded great. Make sure you dynamat the outside of the box that is not visible, stops nearly all of the vibration noise in other parts of the boat.