Can Chopped Strand Mat (CSM) be used with EPOXY?

[STATUE]

I have a niggle somewhere in my head that it is not advised to use Epoxy Resin with CSM.


If not - why not?

What's the alternative fibre mat to use?

All contributions Very Gratefully Received.

 

[JumbleDuck]

I have a niggle somewhere in my head that it is not advised to use Epoxy Resin with CSM.

Standard CSM is bound together with stuff which dissolves in polyester resin but not in epoxy. I think epoxy-compatible stuff may be available.

 

[TangaraToo]

http://www.easycomposites.co.uk/pro...-bound-chopped-strand-mat-300g-per-metre.aspx
You need CSM for epoxy as per link

 

[VicS]

I have a niggle somewhere in my head that it is not advised to use Epoxy Resin with CSM.


If not - why not?

What's the alternative fibre mat to use?

All contributions Very Gratefully Received.

Advice I got was that the CSM for epoxy was difficult to use, compared with CSM and polyester, due to lack of binder I suppose, therefore used cloth.

See "Cloth, fabric & tapes" on the East Coast Fibreglass website http://www.ecfibreglasssupplies.co.uk/c-356-cloth-fabric-tapes.aspx

I used biaxial cloth but off hand i do not remember what weight, but I guess it will depend upon what you are doing

 

[Minchsailor]

Generally, NO. CSM has a styrene binder which dissolves in polyester resin, but not in epoxy; it stops the epoxy wetting the mat.

Use woven instead - no binder.

 

[macd]

The binding agent in most CSM is starch which, as said, is soluble in the styrene in -ester resins, but not in solvent-free epoxy. Thus with the latter the starch both interferes with binding and keeps the CSM stiff and hard to work.

There is such a thing as stitched CSM, which has no binder and is thus OK with epoxy. This stitched CSM is often found in a laminate, one face CSM, the other woven rovings: a good combination, usable with both epoxy and -esters.

 

[laika]

I researched this a couple of years ago when sorting out the blisters on my rudder. Now I came from a practical ability standing start when I bought my boat 5 years ago, have had no kindly old uncle to show me the ropes so my approach has been a combination of book learnin' and, wherever possible, asking "the guys in the yard". Often the two answers don't match and it's educational finding out why...

Read a book on this stuff and the accepted wisdom is not to use regular CSM because, as mentioned, the binder doesn't dissolve in the epoxy as it would in polyester. Instead the advice is to use powder-bound CSM which is, as I recall, both harder to come by and more expensive.

Now asking "the guys in the yard" about the powder/resin binding distinction I was met with blank stares: they only knew about one type of CSM which they used with both polyester and epoxy. They gave me a bit and it was exactly the same as the "ordinary" stuff I already had.

How to resolve this advice discrepancy? Surely if the professionals at a well-known hamble boatyard were routinely doing something really bad someone would have complained?

I found this article on the West site:
http://www.westsystem.com/ss/chopped-strand-mat-epoxy/

Makes interesting reading but bottom line: It's not really a problem using ordinary CSM. The binder doesn't dissolve but it doesn't make a lot of difference. Of course me being me I still went out and bought some powder-bound mat anyway and it didn't seem any harder to work with but IIRC was more expensive.

 

[vyv_cox]

I have used CSM with epoxy many times, mainly because I had a big roll of the stuff. It is certainly more difficult to wet out with epoxy than with polyester resins but it is possible to get it air free and so presumably as strong as with a 'wetting' CSM.

 

[Birdseye]

I have a niggle somewhere in my head that it is not advised to use Epoxy Resin with CSM.


If not - why not?

What's the alternative fibre mat to use?

All contributions Very Gratefully Received.

yes it can ( I have some up in the loft) but its a complete PITA because epoxy is so sticky that you pull the matt to pieces with your brushes and roller. Avoid.

 

[STATUE]

Whew - thanks for bottoming out the confusion I had.

Excellent contributions from every one.

Thanks again

I researched this a couple of years ago when sorting out the blisters on my rudder. Now I came from a practical ability standing start when I bought my boat 5 years ago, have had no kindly old uncle to show me the ropes so my approach has been a combination of book learnin' and, wherever possible, asking "the guys in the yard". Often the two answers don't match and it's educational finding out why...

Read a book on this stuff and the accepted wisdom is not to use regular CSM because, as mentioned, the binder doesn't dissolve in the epoxy as it would in polyester. Instead the advice is to use powder-bound CSM which is, as I recall, both harder to come by and more expensive.

Now asking "the guys in the yard" about the powder/resin binding distinction I was met with blank stares: they only knew about one type of CSM which they used with both polyester and epoxy. They gave me a bit and it was exactly the same as the "ordinary" stuff I already had.

How to resolve this advice discrepancy? Surely if the professionals at a well-known hamble boatyard were routinely doing something really bad someone would have complained?

I found this article on the West site:
http://www.westsystem.com/ss/chopped-strand-mat-epoxy/

Makes interesting reading but bottom line: It's not really a problem using ordinary CSM. The binder doesn't dissolve but it doesn't make a lot of difference. Of course me being me I still went out and bought some powder-bound mat anyway and it didn't seem any harder to work with but IIRC was more expensive.

 

[bikerbill]

I repaired a cigarette pack size hole in a hull using polyester and matting with great success. When it was dry, I was advised to paint over the area with epoxy resin to form a water tight seal.

 

[Iain C]

Why not use weave (plain or twill). What's the job you are doing?

 

[VicS]

Why not use weave (plain or twill). What's the job you are doing?

or biaxial or even triaxial if there is a big thickness to build up

 

[macd]

or biaxial or even triaxial if there is a big thickness to build up

...especially over compound curves. Lovely stuff (but then so are some compound curves...)

 

[rogerball0]

Used Powder-bound CSM when making my own fuel and water tanks for my Centaur and concur; its an absolute ballache to work with, with epoxy although fared little better with fire-retardent polyester. Ended up with a laminating roller that resembled candy floss and wasted a shed load of resin in the process, needless to say i abandoned the idea and bought polyethlene tanks. Also another consideration is theres very little strength to CSM when compared with weaved cloths / bi-axial tri, quad etc which also drink far less resin than the equivalent weight CSM.

I bought my epoxy-friendly CSM here: http://www.ecfibreglasssupplies.co.uk/c-543-powder-bound-chopped-strand-matt.aspx