heat oven - mandatory?

[Innocente]

question:

i'm about to try to make my first fiberglass / laminate bow, is heat curing epoxy mandatory?  is there an epoxy i can cure at room temperature?

[soopernate]

Smooth On and G2 will both cure at room temperature according to their literature.  Just takes a bit longer to get full cure.

[Stagmitis]

http://www.smooth-on.com/tb/files/EA40.pdf

There is always a risk navigating uncharted waters. The problem with not heat curing is a lower strength bond and probability of failure in very hot weather.

[Innocente]

i will most definitely be firing it in very hot weather...sounds like i wanna make an oven and bake it then.  

thanks guys

[Drenalinjunkie]

Read carefully at what they say....

Post Curing – After EA-40® has cured at room temperature, heating the epoxy to 150° F (65° C) for 4 to 8 hours will increase physical properties and performance. Let cool to room temp. before moving bonded substrates, machining, etc.

Looking at this from what smooth-on says is cure at room temp and afterwards place it in a hotbox etc. Dont understand why people say that their bows have delaminated after being in a hot car when looking at this it should increase the epoxies strength... Maybe they are looking for excuses. My feeling is that it could be that the epoxy was not mixed properly or they shot the bow immediatly after taking it out of the car without allowing it any time to cool down....

[Tom Leemans]

Most any bowyer will tell you that they'd rather cook it, than worry about how it holds together later.

For all wood bows though, Urac and Resorcinol don't need an oven. Glue it today and work on it tomorrow.

[Stagmitis]

Not sure about that Tom. I have never worked with Recorsinol(Would love to find some) but I have witnessed several Urac-blowups from the same bowyer on very hot days. That bowyer never used heat.

I cant verify this but I have heard that if you cure a bow at room temperature then the bond is ONLY as strong as the temp in the room. Once subjected to higher temps then the glue begins to soften and kaboom.

Drenalin it also says this right before post curing...

"Apply to prepared surface and let cure for 24 hours. Applying mild heat will cure EA-40® faster – 150°F/65°C for 6 hours.

[Drenalinjunkie]

Stagmitis,

Yes it does say that. It does cure faster but my point is according to their specs and info treating it post curing makes it stronger...  

[Tom Leemans]

If the Urac failed, I can only assume a few things. Either the mix was wrong (not likely if he makes lots of bows) or the resin was on the verge of going bad (more likely), or perhaps the bow was left strung in an extremely hot area for an extended time, then stressed. I've had my bows and several others who use Urac have had theirs at MOJam during a hot year (over 100 deg.) with no problems.

BTW You can do a search for DAP Weldwood Resorcinol Glue and find it at a lot of places, but it looks like the Home Depot stores out your way sell it. Most marine supply stores have it too.

[Stagmitis]

Thats where its a tad confusing Drenalin. You could actually cook a bow "Twice". The first just speeds up the 24 hr cure and the second improves the physical properties. No bowyer I know of does that though.

Thanks for the tip Tom. Im going back to Uraq and want to try resorcinol. Im getting too much glue creep with Smooth-on.