Laminated Bow Epoxy Curing

[Cupcake]

I am curious about epoxy curing.  I have read the Smooth-On epoxy directions and they say 24 hour room temperature cure but a stronger bond is achieved with an additional 1 hour cure at 150F.  My memory may be fuzzy here because it has been a while.

What benifit is derived from heat curing the epoxy at 150F for six hours?  I am wondering why it is needed.  Does it result in a stronger bond than room temperature followed by 1 hour heating?  Or about the same strenght as room plus heat cure?  Does anyone have any test data in this regard?

Has anyone used it after room temperature curing and no heating?

I am going to take the bow-making plunge so I am very curious.

Thanks for tolerating my newbieness,
Kevin

[SOS]

I made a takedown longbow early in the summer and used the old Volvo in the driveway to cure it.  Left the form in the car for 24 hours with temps inside the car getting up to 122 one day and 132 the next.  The limbs survived a dry fire that broke the riser, and are now mounted on a new riser and shooting fine.  In fact as of last Saturday...really fine!

 

[razorsharptokill]

I'm always leary of the hose losing air pressure and letting the lams separate or slip. I check the air pressure every hour or so to be safe. I'd never sleep if I just let the form sit for 24 hours to cure the glue up at room temp. I like to get it cooked so I can relax.

[R.W.]

On another thread on this forum, someone posted that epoxy will SOFTEN at the temperature it cures at.

With that nugget in mind, if one "cooks" the bow to cure the epoxy, it is unlikely that one will be hunting in 150 degree heat, so there would not be a chance of the epoxy softening during a 110-120 degree summer hunting trip.

This gives the bow its best chance of not delaminating because of its glue softening on a hot day, or by being left in a car during a summer day.

The epoxy will also be fully cured after 6-8 hours, too. This allows the bowyer to get back to working on the project, in a shorter time.

[wingnut]

I have been told by experts that epoxy has heat memory and by other experts that the others are full of it.  LOL  We heat cure all glue.  The Urac just cures faster so we can keep working.  The Smooth On sets faster and cures over time.  But the faster set will hold everything together for sure.

We use 170 degrees on Smooth On with heat strips and it sets in one hour.

Mike

[legends1]

We bake smooth-on in the oven 4hrs at 140-150. Then allow to cool.The heat will allow the epoxy to inter the wood grain causing a better bond -Mike

[Crooked Stic]

Read this on the using and curing EA-40
  Smooth-On

[BMN]

After reading the smooth-on data sheet I assume you are using a mixing ratio of 2A:1B?

[Coop]

I always mix smooth on 1:1 and cure it between 150-170 degrees for 4-6 hours and then I let it cool completely before releasing the air pressure. I have made dozens of bows and (knock on wood) I have yet to have a failure.

Anybody know the shelf life of smooth on unmixed? Everything I find just says limited shelf life.

[Crooked Stic]

I use the 1 to 1 ratio and cure in a hot box 6 hours and let cool before releaving the pressure.i have had no delam problems from hot weather so far. You just dont want to leave a strung bow where it will get too hot.

[legends1]

Sorry guy's,my bad.I see now I posted 4hrs. should have been 6Hrs.+ allow to cool in form until next morning.Sorry agian For the mis-information.Never had a delam problem of any kind.  Smooth-on is a wonderful product.I hav'nt herd anyone I know of ever having a problem.-Mike