CSM or Cloth

[BoatDr]

I'm planning on glassing the deck of a late 60's starcraft. Should I use CSM or cloth? I used CSM on the transom, which was kind of a nightmare. Fiberglass sticking to everything! If I should go with cloth, what weight?

 

[chrishayes]

Re: CSM or Cloth

general rule of thumb is 8oz's total. The only concern is that cloth will likely give you a better smoother surface but you will have to sand down overlapping areas.

 

[109jb]

Re: CSM or Cloth

If using poly resin you need to use CSM first. If you do just cloth with poly resin you will be able to just lift a corner and pull the whole thing off. If using epoxy, you can use just cloth and it will bond fine. if you use CSM and poly resin you can make your life easier by getting a resin roller like the ones here.

 

[jonesg]

Re: CSM or Cloth

I'm planning on glassing the deck of a late 60's starcraft. Should I use CSM or cloth? I used CSM on the transom, which was kind of a nightmare. Fiberglass sticking to everything! If I should go with cloth, what weight?

were you using epoxy?
poly resin should go on mat easily, wet the wood first w/ resin, stick mat on and wet it out, I use a 3 inch cheapo brush.
You also don't HAVE to do the whole thing in one shot, do the lower half first, then mix up a second batch and do the upper half using no wax resin. HAve all the glass pre-cut, all the resin batches pre-measured but not catalysed, quick rinse brush in acetone between batches.
Get all your ducks in a row before starting.

And change gloves as often as needed.
Once you become familiar with it all you'll find the mess comes from disorganization and getting resin on your gloves then touching the mat.

Other hot weather tips, keep the resin COOL (basement floor),
measure on the lower end of the scale for larger batches.
My resin calls for 15-17cc per quart ( I think its a qt)
so I'll go down to 14cc's if its hot.
Rather than mix it in a round can or bowl I use a trough so it stays shallow, I have a plastic trough 10 inches long x 4 high and 4 across.

 

[BoatDr]

Re: CSM or Cloth

I think I may go with the cloth because it seems I'd be able to do it a lot faster because I can use a spreader. Tried using a spreader with the CSM my first attempt at glassing and it just kinda moved the strands around in clumps!

 

[Mark42]

Re: CSM or Cloth

Has anyone tried applying resin to the ply, then lay the 1 oz mat and then 6 oz cloth over the 1 oz mat and spread the resin over both at once?

Thats kind of like the 1708 I used, but a lot lighter.

 

[109jb]

Re: CSM or Cloth

I think I may go with the cloth because it seems I'd be able to do it a lot faster because I can use a spreader. Tried using a spreader with the CSM my first attempt at glassing and it just kinda moved the strands around in clumps!

I use a spreader all the time when using csm. Sounds like you didn't have enough resin on it. The way I do it is as follows:

1. spread resin on bare wood with spreader.
2. lay csm over area
3. DUMP more resin on top of the csm and spread with spreader

If the spreader starts dragging fibers from the csm too much that is your signal that you need to DUMP more resin on.

 

[BoatDr]

Re: CSM or Cloth

I use a spreader all the time when using csm. Sounds like you didn't have enough resin on it. The way I do it is as follows:

1. spread resin on bare wood with spreader.
2. lay csm over area
3. DUMP more resin on top of the csm and spread with spreader

If the spreader starts dragging fibers from the csm too much that is your signal that you need to DUMP more resin on.

Ah ha. That must have been the problem. I ended up just blotting a bunch on with a cheapo brush, which seemed to work alright, though much slower. Thanks for the info guys. I'll probably order one of those rollers...look pretty nifty. I like the cloth over the mat idea. Anyone else have any comments on that?

 

[109jb]

Re: CSM or Cloth

Also, after you spread the resin a little, let it sit. The glass fibers need a little time to soak up the resin. Then you can go back and either use the roller, or a brush to stipple the air out. The rollers are the hot ticket though. I've even used a short nap paint roller with good results (The shortest nap you can get). You don't want to roll too hard or squeegee too hard either because you will compress the fibers and they will "spring" back. When they do they will suck in air. Kind of takes a little practice. On a boat it isn't the end of the world if you have a little more resin in there than the minimum. You want to leave enough resin in so that any spring sucks resin into the gap. Kind of like a sponge. Squeeze the water out and when it springs back it sucks air into the pores of the sponge, but if it is in a bucket of water the depth of the sponge it will suck water back in.

 

[ondarvr]

Re: CSM or Cloth

Has anyone tried applying resin to the ply, then lay the 1 oz mat and then 6 oz cloth over the 1 oz mat and spread the resin over both at once?

Thats kind of like the 1708 I used, but a lot lighter.

That's sort of how its normally done, but a little resin may be appied to the top of the mat before the cloth if needed.


Squeegees (inluding bondo spreaders) don't work that well on mat, but can sort of be used, brushes are OK, but slow and messy compared to a fuzzy roller.

It does depend on the size of the job you're doing though, large areas like the floor can be done very fast with a Fuzzy roller (to wet it out) and a squeegee (to remove the air) as long as cloth, roving or biax is the top layer. If no mat is being used, just pour the resin on the surface and move it around with a squeegee. On a small job there's too much resin wasted with a fuzzy roller.
On small items, like doing a 6" repair, a brush works fine on any type of material, as you get larger a brush slows things down and can be a little messy.