Whats the best way to glue this corbel?

[ron_churches]

Hi,

I am wondering if anybody has an opinion about the best way to laminate these edge glued panels together to make the finished corbel. I'd like these to hold up for as long as possible and am concerned about expansion and contraction that will occur being outside in the Michigan weather. Is it best to cover the entire mating face with glue (Tite Bond III in this case) or a bead around the perimeter with a few lines across the interior. The panels are made of Douglas Fir and according to my "drop testing" on scrap pieces, are brittle and will not break along the glue joints but split fairly easily elsewhere in the board. If I go with a few lines of glue across the interior of the panel, should they go with the grain or perpendicular to it? Any thoughts on the subject are appreciated

[scottp55]

The whole surface Ron and a good even layer, if you don't have a ton of clamps use some scrap wood wrapped in wax paper to distribute pressure. You should see a good uniform squeeze out.

[ron_churches]

Thanks Scott !

[scottp55]

Welcome. Don't miss anywhere, voids and exterior don't mix well. Those glue rollers work well if you remember to clean them, but shingles and scraps are good glue spreaders in a pinch:)

[steve_g]

I agree with Scott, a full even coat. The reason “gorilla” glue (foaming urethane) doesn’t get good exterior ratings is due to moisture getting in the bubbles and expanding during freezing weather… The lesson is no voids if possible!
SG

[POPS 64]

I agree with Scott to . And being from Michigan I've done a few of them as a retired carpenter . lots of glue even a couple galvinized finish nails very good primer and paint and dont wait for them to peel .Before maintaining them. Jeff

[Ajcoholic]

Yup, glue the whole surface.

I would love to test this - sandwich a layer of 6 or 8 oz glass cloth between them and use a good laminating epoxy resin like West System. I think it would hold up even better.

AJC

[scottp55]

Almost a shame to paint them after the solid wood glue up work. Good job.

[gc3]

tb2 or epoxy on complete surfaces, glue up no more than 6 hrs after machining pieces

some web info...

Under typical environmental conditions Titebond II and Titebond III are equally resistant to water. However, Titebond III exhibits greater thermal plasticity, which is a technical way of expressing that it loses more strength as temperature increases. Since all PVA adhesives form a plastic film when dried this plastic will effectively melt once a sufficiently high temperature is reached. Titebond Original and Titebond II lose about 50% of their strength at 150 F whereas Titebond 3 looses 80% at 150 F

we stopped using tb3 after panel failures on fully exposed exterior doors

http://www.woodweb.com/KnowledgeBase/KBAdhesives.html

[kevin]

I didn't know about the heat with pva
gorilia glue is over rated wast of money and expensive
I use for exterior also use in the shop
Using for over 10 years http://www.lepageproducts.com/ProductDetail.aspx?pid=84

[scottp55]

Good to know Kevin as we have similar freeze/thaw cycles. Curious Kevin, Do you have "January Thaw"? Glad I don't get the type of temps in winter others do because of ocean 4 miles away.

[mikeacg]

Since you are going to paint them anyway, I would be tempted to use pvc instead of wood. I use a Trex-like product for trim work on my old house up here in the UP and it holds up great.

Mike