Resourcinol

[Cliff Rohrabacher]

Last year I made a couple of tongue drums.

The cross grain joints at the top / sidewall interface failed within months. I attributed it to humidity change and expansion 'cause of the cross grain joint.

I disassembled them and observed that the cross grain joint where the failure occurred seems not to have many torn wood fibers where the joint failed. It was a tight joint. Maybe I over-squeezed it.

At any rate I elected to attach a new set of tops using resourcinol. I need the experience as I have a resourcinol glued project coming up.

The spec sheet says ya gotta work it at no less than 70 Degrees F.

I e-mailed the company asking if the assembly could occur at less than 70 as low as 50 - 60 Deg F then put a heating thermal blanker on it or take it to a warm room and the answer was"
"The air temperature and materials must be at 70 degrees Fahrenheit in order for the product to activate and be of any use. The adhesive will not activate at any lower temperature nor will it form a bond if the temperature later comes above 70 degrees. Thank you again for contacting us."


Which pretty much puts the Kybosh on a great deal of what I have heard on the net in various places where people take the assembly and then apply heat for a few hours.

However this guy's title was "Product Information Specialist"
And not "Chemical Engineer." Which means that the data he provided may simply be based on the spec sheet and nothing more. It's possible they haven't even tried using the stuff outside it's engineered envelope.

So I'm wondering whether others have tried resourcinol at temperatures less than 70 Deg F. and if so, what was your experience.

[Alex Carrera]

I will have to search for a document I found written by a yacht builder. In it he talks about a "winter grade" resourcinol that works down to 50 degress and will also fill gaps, unlike the stuff that I've been able to find. He said you could only get it mail-order in the US. Anyone know what I'm talking about?

[Cliff Rohrabacher]

I have read about a gap filing variant. If I recall correctly it's not got as robust a bond.

[Al Willits]

Running into the same problems I like to keep the shop at about 55-60 when I'm out there, I did find out that at 50 resourcinol with stay sticky at 4 hours and when I brought it in the house where it was 68 it didn't help, after half a day I could still pull the joint apart.

Had the same problem with epoxy and cold temps, although it seemed to set up when I raised the garage temp to about 65 or so, not sure how strong that joint is though.

Looks like I'll have to make a little booth to glue in and keep the temps higher.

Al

[Cliff Rohrabacher]

I did find out that at 50 resourcinol with stay sticky at 4 hours and when I brought it in the house where it was 68 it didn't help, after half a day I could still pull the joint apart.

Ouch~!! Was that the DAP brand?

I bought the DAP product and made some Maple joints last night. Left 'em in the hot part of my cellar off the garage/shop. The shop was about 65 the cellar was warmer. I also made some Maple joints with Titebond.

In the morning I Trued to pull one of each apart. Both gave but the Titebond pulled a fair size splinter of maple away. The Resourcinol didn't but the break strength was about equal - - so my arm tells me.

The resourcionol glue squeeze out was a tad soft. When I ran a chisel through it it came of in a nice flexible peel.

So I took everything upstairs and turned the heat up past 70 and set 'em all near a radiator.

Hours later the glue is harder. A chisel takes the squeeze off in crackling bits and it's tougher.

Maybe I had it hot enough down stairs in the cellar that the cure got a start??

In the cooler shop the drips laying around remained a tad gooey but not tacky.

I have yet to try to break the "cured" joints.

[Al Willits]

Cliff, this is what I tried, its from Rockler.

http://www.rockler.com/product.cfm?page=17439

I was more expriementing than anything else, I wanted to see how low I could go and it'd still work...musta went a bit too low...:)

Seems the epoxy works better at lower temps, so if I can't get warmer temps I'll use that, still want to try to use the resorcinol as I'm thinking of doing some laminating and I'd like to use that, just have to fire the furnace up that day..

I'm also wondering how long I'd have to keep at 70 or so, wondering if I had it there for a hour or two then dropped the thermostat back down to 55 or 60 if it would be done curing in the hour or so it took to cool down??

All else fails I'll read the directions....:)

Al

[Cliff Rohrabacher]

Resorcinol (DAP Marine Weldwood product) outside the specification parameters.

I have been trying to wrap my head around resorcinol use in situations where the appropriate temperatures can not be achieved.

I have an oak Chair project coming up. I had planned on using Resourcinol as the glue but I am rethinking that choice of glue and am now leaning toward Epoxy. There will be M&T joints - lots of them -M&Ts GALORE~!! And all of them will be critical structural joints. I am learning that resourcinol requires clamping pressures that an M&T simply won't allow because of the physics of the joint. ERGO: the lean toward epoxy.

However, because the chairs will all be outside all year long in the north east I want repairable and waterproof glue joints. And yah I read Bob Smallser’s post on repairability. That's why Titebond III is no good.



Everyone knows: The tech sheet says you need minim of 70-Feg-F. The tech help line guy (not a Chemical-Engineer) answered my e-mail about assembling below 70 and then curing at or above 70 by saying:

“The air temperature and materials must be at 70 degrees Fahrenheit in order for the product to activate and be of any use. The adhesive will not activate at any lower temperature nor will it form a bond if the temperature later comes above 70 degrees. Thank you again for contacting us.
Sincerely,
[name omitted]
Product Information Specialist”


OUCH~!! "be of any use" ~ ~ ~ "will not activate [...] nor form a bond if temperature later comes to 70 degrees" Those were some stern words~!!


Yet, I read often enough in forums like this about people assembling at temperatures below 70 and then applying a thermal blanket or removing the work to a heated area. Clearly, there are anecdotal experiences that seem to contradict the information I got from the DAP “Public Information Specialist.”

So:

I made a bunch of lap joints in maple using Titebond (Tit) and Resourcinol (Res). Surface area of the glue up was 1” square. I mixed and assembled and let them sit at temperatures lower than 70Def F. Average temp ranged from 56 – 67 Deg F.

Some joints were cross grain some were long grain.

The Tit group was my control group since I have a fair experience range with that glue and know what to expect of it.

A separate set of lap joints was in Res to play with the idea of Gap Filling.
The gaps were produced by cutting a saw kerf 1/8” deep and wide in an unaligned X pattern on each faces of the mating surfaces. I added some wood flour by eye to the Res glue till it was dense paste then used that paste to assemble the joint.

Clamping on all joints was nothing more than a hand spring clamp – definitely not the 200 PSI required for hardwoods and Res.


The joints were all assembled, clamped, and left to set for 20 hours (arbitrary).

After the 20 hour period The joints were examined. The Res glue squeeze out was hard but, not terribly hard. Not tacky but, a chisel sliced off a flexible peel. The Tit glue was set and hard, as it should be.

The Res glue joint sets were then placed in an area with a temperature above 70Deg-F (about 80Deg-F) and left to set for 3 hours.

After sitting at the higher temp' the Res glue squeeze out appeared harder and chiseled off with a more hard slightly brittle feel and texture.

The joints were manually stressed to breaking. The Res joints broke and the Res glue ripped off very shallow and small wood fibers from the joint faces indicating that there was almost no penetration into the fibers from the light clamp pressure. But, also indicating that the adhesion did activate and the bond did occur.

The Tit joints broke and pulled substantial splinters off the mating faces - as expected.

The force exerted to break the joints was similar enough in all of the joints that I could observe no distinction on the highly sensitive research instrument that is my arm.

The Res glue Gap Filling test joints produced some what more remarkable results.

When stressed to breakage the Res glue pulled of substantial amounts of wood. However the wood ripped from opposite faces was not torn from the gap filled area.
This led me to conclude that the paste texture of the Res glue helped prevent squeeze out and facilitated a deeper penetration of glue into the mating wood surfaces.

I think I’ll do it all over again with all the work at of above 70Def-F and this time I’ll use some hefty Forged C clamps to get clamping pressures up to spec too.


One conclusion that I am coming around to is that there may be no meaningful distinction in holding power between any of the better glues until factors other than sheer bond grip strength are introduced: such as creep, continual load, substrate expansion/contraction, and heat. Since my intended project ( of Oak) won't see much heat or immersion in water but, can't be clamped hard and won't be assembled at or above 70Deg-F, I think Epoxy is going to be the best glue choice.

Tightbond III would have been but for the repairability problems. I can always clean and reglue epoxy joints.

[Cliff Rohrabacher]

Cliff, this is what I tried, its from Rockler.

http://www.rockler.com/product.cfm?page=17439



That's the stuff I bought.

In hard woods ya gotta clamp the living BEGEEBUS outta it. I can't guess how the clamp pressures they require don't starve the joints.



I was more expriementing than anything else, I wanted to see how low I could go and it'd still work...musta went a bit too low...:)DAP says not at all below 70.



Seems the epoxy works better at lower temps,AND you don't have to clamp it with like 100 PSI.



I'm thinking of doing some laminating and I'd like to use that, just have to fire the furnace up that day.. And fine some really big and heavy ingots of lead to cover every square inch of the lamination. cause you need 75 PSI to force the glue into the wood.



I'm also wondering how long I'd have to keep at 70The DAP spec sheet says 8 - 10 hours

'There is a DAP tech sheet here:
http://www.dap.com/docs/tech/00030205.pdf
They say you need 75 PSI.
I have seen another data sheet It was a Bostick product that calls for 200 PSI


or so, wondering if I had it there for a hour or two then dropped the thermostat back down to 55 or 60 if it would be done curing in the hour or so it took to cool down??Nooooooooo
The DAP spec sheet says 8 - 10 hours at 70 Deg-F

The more I learn about the stuff the more I understand why so few people use it.

In reality it has only two characteristics that make it superior - and only if you need them. They are:
1.) Boil proof - you can soak it for ever and it won't fail.
2.) heat resistance. Marine and other Epoxies fail when heated. There are some that you can't even put dark paint over if you are in the tropics. Resorcinol does not. It can take tropical sun all day every day and it won't creep or delaminate.

Resorcinol is not a good gap filler, It requires HUGE clamp pressures, it is super finicky about temperature, and it is purple. Those characteristics inform me that if I can possibly use any other glue - - I should.