Epoxy adhesion to resorcinol

[Sayla]

I've read that epoxy will simply not adhere to any area smeared with Titebond - does anyone have experience with epoxying over resorcinol glued timbers? Are there adhesion problems at the resorcinol spots?

thanks
Sayla

[AndreasJordahlRhude]

You're attempting to glue on glue? I can't imagine any adhesive being able to stick to other adhesive.

Sand or plane off the old adhesive and start with fresh wood.

[waynec]

I've read that epoxy will simply not adhere to any area smeared with Titebond [ brand resorcinol ] - does anyone have experience with epoxying over resorcinol glued timbers? Are there adhesion problems at the resorcinol spots?

In looking up the more popular two adhesive brands, neither Weldwood (DAP) resorcinol nor WEST System address adhesive compatibility of the two glue types. Though they do mention one another in a generic sense, no precautions are given either way. BTW - Titebond's current catalog does not show a resorcinol adhesive.

The noticeable difference between the two is the Bond Strength or "compression shear".

Weldwood Resorcinol = 2,800 PSI

WEST 105 = 11,418 PSI

Data Sheets -
DAP® WELDWOOD Waterproof Resorcinol Glue
http://www.dap.com/docs/tech/00030205.pdf

WEST System Typical Physical Properties
http://www.westsystem.com/ss/typical-physical-properties

I would be interested to read the caution you came across. Is it available on the web?

All I can determine from the data given is, applying a stronger gripping adhesive over a lower gripping one does nothing to increase the first adhesive's grip.

.

[mariner2k]

I believe Bob Smalser couuld answer that for you.

[RodB]

Cured Resorcinol will be an inert substance... with a clean sanded properly prepared surface... epoxy will just about stick to anything... as usual, you can always do a test strip..


RodB

[Sayla]

I would be interested to read the caution you came across. Is it available on the web?

It's from thread on here
http://forum.woodenboat.com/showthread.php?t=114448

After reading the above thread I wondered how areas such as resorcinol laminated keel woods went with epoxy / fabric over, after sanding of course, and hopefully only small lines etc of resorcinol showing - but nevertheless showing.

Thanks Rob - I figured it would probably not be a big issue with resorcinol, but nevertheless I have seen coatings on lam beams peeling away from the glue lines.

Sayla
Sayla

[ssor]

The noticeable difference between the two is the Bond Strength or "compression shear".

Weldwood Resorcinol = 2,800 PSI

WEST 105 = 11,418 PSI
I checked the shear strength of wood parallel to the grain and the best I found was black locust at about 2450 psi.