Boat Builder Central - Builder Forums

I believe there is a simple misunderstanding. If y'all could calm down & research a tad more, you're 'argument' wouldn't be needed.

CSM, as a stand alone product, typically has styrene binders that dissolve when polyester or vinylester resins are applied. It basically 'melts' apart and conforms to what you're applying it to...sort of. Epoxy will not dissolve the styrene binder and makes it sort of useless. HOWEVER, there IS a CSM product available that has a powder binder instead of the more common styrene binder. The powder binder IS compatible with epoxy.

Now on to 1708 (and 1208 for that matter). The 08s do indeed have CSM attached to one side. They do. That's what the "08" is...CSM. With that said, the 08s DO NOT have any binders because they are stitched. They are held together with the stitching, and binders are not needed. Because of this, the 08s are compatible with epoxy, poly, and vinylester.

1700(1200) is the product that does not include CSM...and typically a better choice when using epoxy.

Thanks cape fisherman. I agree no more comments from me.

No attempt to argue cf. I even apologized in advance for my tone AND asked for edification.

The other thing I did wrong here was the math. The stuff is 0.75 oz per square foot or 6.75 ounces per square yard. I am not sure why they use the 08 numbering. I tend to treat the 8 as 8 ounces in my pea brain.

I have used actual csm with epoxy. The epoxy does not need to break down the binders for certain applications. For other applications; the binder breaking allows for greater movement of the glass and is essential.

If one scours the interwebs for details on how 1708 is made; it is rather hard to find. There is some way the chopped strand mat is held together to end up attached to the db. I will see if it is stitched. I never noticed stitching thru and thru.

I have used some 1708 that is rather stiff and makes funny noises. It is either a coating applied to the entire fabric or something used to hold the mat portion together. Not sure which. And it is not all the time.

All trying to be straight is all.

I used veil on two of the Skoota hull panels. It was csm. Epoxy does not care. The veil layer did not accomplish my wishes. I have a whole roll of it if anyone knows wjat to do with it! It was like $450. I used maybe 70 feet of ?100 or 200 yards.

See below ... ...

Not sure how easy, or difficult, the stitching is to see here...

^^^^ That's the stuff Tom (thb) sent me to help build thickness for the rocker I had. It's stitched like that. And it takes a TON of epoxy to wet out!

Maybe they spray a bit of binder to hold it until stitched and that is the scrunching noise I hear.

piperdown wrote: ↑Sat Feb 20, 2021 3:19 pm And it takes a TON of epoxy to wet out!

Which is why builders I know don't use it. Takes twice the amount of epoxy for not even half the amount of strength. A friend of mine that builds custom sportfishers out of wood & epoxy doesn't have a single yard of 1708 in his shop. He's a 1700 guy through & through.

There may be a problem with terminology here. In this discussion, CSM stands for Chopped Strand Mat not that Chloro something stuff.
CSM is normally the chopped fiber that comes out of a chop gun used in fiberglass boat production but it also exist as a fabric in which all those glass strands are kept together with a binder. Some people call the fabric version, it is correct if you want but many more just call it mat.
The binder can be of different types and yes, some are very stiff.
1208, 1708 etc. are made with mat stitched to the biaxial.
I very rarely specify it because as Fallguy writes, it soaks up resin without adding much strength. However, when a laminate is sufficiently strong but not stiff enough, I need to increase that stiffness by making it thicker and that is where 1708 comes into play. It is cheap and bulky, it makes that panel stiffer.
The 1708 sold by Jeff, is compatible with epoxy.

1708 = 17 oz biaxial + 8 oz CSM stitched together. That's the definition of the stuff. It always have CSM.

Most 1708 has a binder compatible with epoxy these days.