Fiberglass mat with Epoxy resin?

McReef · #1 03-04-2011, 02:52 PM

I have read in a couple of different places that mat should not be used with epoxy resin. The explanation given is that the binder used to hold mat together is a styrene soluble "adhesive", and epoxy, not containing any styrene like is ester cousins, will not properly wet it out as a result.

Thoughts or input on this?

My original plan was to use 1708 and 1808 biax for my project, but given that the plan is to use epoxy resin, now I am not so sure. Perhaps I should go with straight cloth instead?

Bigshrimpin · #2 03-04-2011, 03:42 PM

based on my experience 1808 does not have the glue binder, unlike 1708 which is generally has a glue binder. I have heard there are some tricks that can be used to dissolve the glue binder with a little acetone, but buying correct stitchmat that is compatible with epoxy (i.e. no glue binder) is the right way to do it. Otherwise epoxy + mat with glue binder turns into a flexible rubbery mess that never cures.

Blue_Heron · #3 03-04-2011, 05:41 PM

Quote:

Otherwise epoxy + mat with glue binder turns into a flexible rubbery mess that never cures.

Hey Tim,
I've used mat with epoxy, and though it does turn into a gooey mess, I've never had a problem with it not curing. The biggest downside I've noticed with the mat/epoxy is that it won't conform to corners or curves because the binder doesn't dissolve. Chopped strand Mat is clearly intended for use with resins that dissolve the binder.

I've also used 1808 and 2408 biaxial stitchmats and never had trouble wetting it out with epoxy.

Dave

newellchunker · #4 03-04-2011, 06:15 PM

I've been using 1708 and 1.5 oz mat with epoxy and have had NO issues! The 1708 is a bitty to get it to conform to corners but we've made due.

Seacraft84 · #5 03-04-2011, 07:17 PM

My father built two boats last year with 1708 and epoxy and did not seem to have a problem. Are some 1708 cloths different?? Is it the different mixtures of epoxy?

KenB · #6 03-05-2011, 02:50 AM

I agree with shrimp but I think there is some 1708 that is more malleable, which might work with epoxy.

My plan is to coat the back of whatever poly I plan to cover with epoxy first before laying down mat and resin... I think epoxy with less that a few days of cure will bond to fresh resin. (old poly bonds to epoxy, which bonds to new resin... old epoxy will not bond to new resin...right?)

Dumb idea? Only one way to find out!

McReef · #7 07-01-2011, 11:58 AM

I realize this is a few months after the question was posed, but I figured I'd report back with what I have learned along the way in case someone else goes searching for answers and finds this thread.

I'd also like to thank those who chimed in earlier for their help.

From what I have seen, both 1708 and 1808 biaxial fabrics from the same manufacturer are both equally compatible with epoxy resins. I would be inclined to think (you should verify this before buying materials for a given job) that most any biaxial, triaxial, or quadraxial stitched fabric would likely share this trait and be compatible with epoxy resin systems (with exceptions)

The key to making sure you get what you want/need in a particular material is to due your homework and know what you are buying. While there are plenty of vendors out there who sell fabric as (for example) "1708 Biaxial Fabric", it should be noted that there are multiple manufacturers of this type of fabric, and it would behoove you to ascertain who it is that supplies your vendor with fabric so that you may investigate their product's suitability for a given purpose.

When it comes to mat, the vast majority of what you encounter for retail sale is indeed likely to contain binders. Those binders, as mentioned by others, render this type of material unsuitable for use with epoxy resins. However, there are mat materials available that do not have this problem, you just need to do your research.

Here are a couple links to manufacturers of fiberglass reinforcement fabrics, you should be able to find just about anything you need there. They also have listings on their sites of where their products may be purchased.

Fiberglass Industries - Biaxial Page

Vectorply - Fabrics Information Page

shine · #8 07-01-2011, 02:28 PM

Biaxial glass (with matt) will vary in the amount of binder used depending on the manufacturer. Just be sure the biaxial cloth you buy (if it includes matt) will wet out with epoxy. We use/sell epoxy exclusively and the 1708 we sell will wet out almost transparent, its held together with stitching, no (almost no) binder.

With epoxy laminates, the only reason to use matt tis to build thickness quickly. Matt is not needed for inter-laminate bonding as it is with polyester. Unless I trying to build thickness, i use combination of biax without mat for all my bonding. For instance, 2 layers 12 oz biax is much stronger than 1 layer of 1708, but it uses less epoxy (less overall weight)

I have two different biax for the rebuild of my 23SC transom. you can see the difference in the two. Here are two layers of the good (more stitching, less binder) 1708 overlapping a PVC pipe along the keel.

and here is a layer of 1810 with a lot of binder in it.

it is a pain to wet out and I would only use it on simple surfaces and curves, but it does build thickness quickly