Chop Mat Questions..

[hdorre]

Ill be glassing my doors, a pillar, and do some glassing around my spare tire. The curves aren't overly sharp, but sharp enough to mention.

Basically, I have two questions:

1) What weight mat would you use for each of these applications? It'd be nice to use the same size for everything. My options are 3/4oz, 1 1/2oz, and 2oz.

2) How many layers would you do for each application? Just a note.. Each door will have 2 PWX6.5 mids, and each a pillar will have a Hertz tweet.. so not insanely heavy. Id rather use too much, rather than too little mat.. if ya know what i mean

[CleanSierra]

I use 1.5 oz matt and it's very easy to manipulate and not too stiff. For doors, you're initial fabric layer(whichever you choose) needs soaked first and allowed to setup. After that, 2-3 layers of chop matt and overlapping your edges while you do it. I hand tear mine, and choose NOT cutting into squares. I get better overlap without having any kind of hard defined edges when it's done.

1) Wrap piece with fabric and secure with staples or hot glue(I prefer the hot glue)

2) Soak piece in resin and allow to setup and harden, giving you a nice canvas to allow the fiberglass to flow over the existing shape

3) Lay piece by piece of chop matt as you go and soak with resin until your canvas is covered entirely with resin and fiberglass

4) Allow cure time(where you can press your bare hand to the fiberglass and it doesn't come back wet)

5) Repeat steps 2-4 for every layer

6) Apply a layer of body filler once cured. Knock it down after 10-20 minutes(depending on how hot you mixed your batch with hardener). This is your green stage and easiest to get big high spots knocked down. I use 36 grit in this stage. When it starts to cure, I go down to 80. If your body filler isn't cured, your 80 grit will load up and become covered in slick, sticky filler. Stop if this happens and allow more time before sanding any further

Hunter, I know that's more than you needed or wanted, sorry. 1.5 oz matt should work for you perfectly.

[hdorre]

God damn.. Thanks Justin. Don't apologize hahah.. Lemme get out a pen and paper

[CleanSierra]

I think this may be they only time I've seriously written it out. Maybe not, I can't remember. Someone wanted me to write out a long step by step process a long time ago. If I ever get time and motivation I'll try to get a thread on the Fabrication section and see if it can get stickied.

[CleanSierra]

Also, I forgot to add, while you're layers of matt soaked in resin are still wet, they sell a roller that helps lay the matt flat by gently rolling over it.

[hdorre]

Thats on the list

[mbdblue]

I would agree with clean....but I do multiple layers at a time. it tends to move faster that way, and if your mixture isn't too "hot", it won't warp anything. However, sometimes it is a little more difficult depending on the size of your project....If it's too big, you might end up wasting resin because it will start to setup while your in the middle of the next layer. Not really a big deal, you should just start in the general area where you left off.

Another note, if you want to be super particular about counting layers or making sure its even, you can do what Tim (groundpounder) used to and cut the mat to fit.

[broncosean]

To help knock the high spots out quick while the body filler is only about half way cured, like a playdoh consistency, you can buy a cheese grater (body guys use them and yes it looks like a legit cheese grater), you run it accross the areas to shape and knock off high spots. Its will literally grade it off then go back over with sand paper for a smooth flat finish