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bloggs68
11-17-2005, 06:34 AM
Hi all,

I have tried to search the forum for this question but he search function seems to be down.

Can anyone point me to or advise what are the correct "needs" of resorcinal glue? I am aware that there are temperature issues and most people I talk to seem to shy away from it claiming they need massive clamping pressures to use it correctly.

Does anyone have links to a manufacturers webiste or similar that discussed temp and clamping issues in particular?

regards,

Andrew

Ad Max
11-17-2005, 08:02 AM
Andrew, info on resorcinol, clamping pressures/time, temperature/humidity can be obtained from the supplier, either from the internet or via a tech data sheet which should only have to be asked for. I did manage to purchase some that was made in Australia a few years ago but was somewhat disappionted with the results, did adhere (pun) as close as possible to the manufacturer's requirements but the only thing that involved guesswork was the clamping pressure, used a hydaulic press. Was in a mad rush as I was doing open keel surgery and had truly outstayed my welcome on the slip and the joints in question were really being secured mechanically. Other thing to watch out for on resorcinol is that I suspect it has a shelf life and I know most of the people that supply it in say 1L or 2L amounts decant this from a 200L drum that would easily be over 12 months old. I can't recall the manufacturer but would suggest looking at the yellow pages under adhesives and chemicals and make a few phone calls. I think for many reasons I would now use epoxy, maybe joint design and types of timber used may be more important then the epoxy/resorcinol question.
Good Luck!

TimothyB
11-17-2005, 08:23 AM
Resorcinol is a picky adhesive, but it has a long history of use in the marine environment, and meets various milspec requirements for gluing. It needs tight fits, good joinery and strong clamping pressure, as well as a reasonable range of humidity and temperature. In some cases (as with white oak) to meet milspec you need to heat the glue line to 150 degrees F for 8 hours to ensure a proper cure.

http://www.dap.com/product_details.aspx?product_id=43

DAP makes it, a 2 part which shouldn't have as much of an issue with shelf life.

It ends up being something like $20 per pint, but a pint goes a long way.

Glider
11-17-2005, 08:59 AM
Andrew,

I'm not an expert, so this is just MY experience.

I tried to glue Siberian Larch with resorcinol (it is rather resinous wood). I tried MANY different variants (pressure, solvents, sanding, prime coats, etc.). I tried two suppliers of the glue. However, I was not able to get a proper bond (test samples broked on the glue line). I came to the conclusion that I cannot manage it. Since I know that Siberian Larch is being used for GluLam constructions, I think that I was doing something wrong. However, I don't know what. I gave up and decided to use solid timbers.

From what I read, resorcinol glue is a *superior* for boat construction (if properly used). I just recommend to perform comprehensive tests before gluing boat parts to ensure that you get a proper bond.

Andrey

Glider
11-17-2005, 09:04 AM
I have tried to search the forum for this question but he search function seems to be down.
As far as I know, people are using Google to search this forum (http://www.google.com/advanced_search?hl=en&as_sitesearch=woodenboat-ubb.com/ubb/).

Bob Smalser
11-17-2005, 09:13 AM
The key requirement is 70 degrees or more farenheit of temperature for 8 or so hours of cure time. On a large project, that's difficult for me in this cool climate without heat blankets.

Clamping pressure is also critical but not unusual...just torque the Jorgies down tighter than you would for Titebond. Where clamping pressure is often an issue is where the builder relies on fasteners to "clamp" the joint instead fo clamps.

Billy Bones
11-17-2005, 09:25 AM
About the WBF searches...go here:

http://www.handforged.net/wbfsearch/

Bruce Hooke
11-17-2005, 11:44 AM
As Bob noted, getting good clamping pressure is not a big deal IF:

A) You've got nice tight, clean, smooth joints that fit together with no gaps before you even put a clamp to them. A lot the time with boatbuilding it can be a challange to machine perfect glue joints.

B) You can effectively clamp the joint with some good solid bar or c-clamps. A lot the time with boat building it can be hard to get clamps around a joint.

Ken Hutchins
11-17-2005, 09:06 PM
I've had good results with resorcinol on lots of joints. What has already been stated, good joints, temperature 70 F.(I've glued down as low as 60 F. without a problem except that it takes 2 days for the glue to harden) and of course proper clamping. I generally try to apply a good C or bar clamp for each 15 or 20 square inches of clamping area, tighten the clamps just as tight as possible with hand pressure, occasionally suplimented with pliers to get slightly more force. Most important DON'T remove the clamps until the glue is properly set, if you can make a mark in the oozed out glue with your fingernail it is not hard enough to remove the clamps, be patient leave the clamps in place and work on something else until the glue is hard. At 70F I leave the clamps in place for a full 24 hours. If a quick setup is needed I heat the parts to 80 or 90 F.
On the really good side unhardened resorcinol is cleaned up with that magical solvent, plain old cool water. smile.gif I've been using the same 'disposable' glue brush and plastic spoons for mixing for 4 or 5 years and hundreds of joints, I use a jelly jar for a mixing container had to replace that because I dropped and broke it. :(
Because of the need for good joints it is not ,read SHOULD NOT be used for gap filling so the amount of glue used is considerably less than some other glues which makes it very economical.

[ 11-17-2005, 09:16 PM: Message edited by: Ken Hutchins ]

Ad Max
11-18-2005, 06:54 AM
Andrew, update on the resorcinol due to finding info.
-moisture content of wood 10/12% ideal,8/14% max
-clamp @ 11kgf/cm softwood, 14kgf/cm hardwood
-pressure period 15C/10hrs, 20c/8hrs, 25c/6.5hrs

There is lots more info but that's the basics. For whats it's worth, the resin I used was Lauxite PR2238 and Hardener 2237 made by Hunstman Chemical Co. based in Melbourne, sales office in Sydney (02) 9672 7144. This is classified as dangerous goods so shipping can be expensive, another problem is dealing large companies for small quantities, I suspect they probably supply in 200 litre drums. PR2238 is stable for 2yrs in closed container, Hardener 2237 is stable for 1 yr in vapour tight container, if it has been decanted, use within 2 months.

Cheers

Nicholas Carey
11-29-2005, 01:47 AM
Some time back (2 years, actually), I wrote here (http://www.woodenboat-ubb.com/cgi-bin/UBB/ultimatebb.cgi?ubb=get_topic;f=1;t=006736) the following, derived from DAP's instructions and various papers published by the USDA Forest Service's Forest Products Laboratories (http://www.fpl.fs.fed.us/) — your tax dollars at work — and similar resarch organisations in Canada and Australia:
WRT to what people have said about resorcinol's need [for] thin gluelines, clamping pressure, etc.:

Bear in mind that using resorcinol successfully requires much more care than many other adhesives in order to achieve good bond strength. For starters (from DAP Weldwood's instructions and other sources):

1. The temperature of the wood, the glue and the work area must be not less than 70F. If less than 70F, bond strength will be insufficient.

2. Resorcinol's cure is sensitive to relative humidity. Moisture content of the wood should be between 8-12%. Wood moisture content of less than 5% or more than 15% compromises bond strength.

3. The glueline should be about 0.005 inches in thickness that's 1/200 inch or 1/8 millimeter or bond strength is compromised. Too thin and there's not enough adhesive in the joint. Too thick and the adhesive fails rather than the wood.

4. Resorcinol requires extremely high clamping pressures. DAP recommends clamping pressures of 25-75 psi; other sources (FPL and its Australian and Canadian equivalents) recommend clamping pressures of 100-200 psi in order to optimize bond strength.

It's exceedingly hard to achieve these kinds of pressures uniformly without specialized equipement. Bear in mind that even vacuum bagging, considered a superb means of applying high clamping pressure for gluing, can achieve only a theoretical pressure of 14.7 psi at sea level. Resorcinol requires 2-10x that. And mechanical clamps, unless you use a lot of them, don't supply uniform pressure.

Epoxy's ease of use and tolerance for imperfect gluelines, low clamping pressure and temperature have lot to do with why it's as popular as it is.Sadly, I failed to cite the sources, a lapse for which I apologise. I still trust the sources from which I drew the information, though.

However, I did go on to provide a pertinent ANSI standard that's readily available for a reasonable price:
ANSI/AITC Standard A190.1, American National Standard, Structural Glued Laminated Timber provides details on layup requirements.

It and other helpful standards regarding the design and manufacture of structural glued laminated timber may be purchased from http://www.aitc-glulam.org/ at reasonable prices (for example, A190.1 is $11.00).

Bernadette
11-29-2005, 05:42 AM
we used resorcinol throughout the entire build of our schooner. we built the yacht in a tin shed in the tropics...read HOT! mix it up. dont breath in the powder dust or you will choke...slap it on, clamp and or nail..hey presto! a good strong joint. many times we tried to break the join on a test peice but the glue line always held and the timber would give way either side. i hope it works anyhow, because thats all thats holding our masts together!!! the glue can be purchased from AVS in brisbne.

seo
11-29-2005, 08:15 AM
I used resorcinol quite a bit to make large roof trusses for equipment sheds and pole barns. The plans came (I think) from the University of Nebraska Ag school extension service, and were surely based on USDA Forest Products Lab work.
The truss gussets were half inch plywood, resorcinal glued to the 2X truss parts. Clamping was by lots of nails (2" pattern). Strength was remarkable, as proved by destructive testing.
We once dropped a 48' truss from 20' up (possibly by accident). All of the chords broke, but none of the gusset joints ruptured.
Another building was knocked down by a tornado after three years. Once again, many, many chord breaks (2X12) Douglas Fir, but none of the gussets failed.
There is a very large manual developed by the Navy for building minesweepers. Don't know what it's called, but it is reputed to be maybe a little over-complicated?
When looking for high clamping pressure, I use lots of steel pads to distribute the force of clamping. Also sometimes drill through the part, and put through a 3/4" d. clamping bolt set up on 1/2" thick by 6" square steel washer plate. Remove the steel when the joint is set up.
seo

HarryH
11-29-2005, 08:32 AM
Bloggs68-

Milspec, ANSI and/or other engineering standards notwithstanding, thousands of amateurs and pros successfully use resorcinol in their backyards/basements/shops. The max strength of resorcinol when cured under such clamping, heat, humidity, etc. specs may be well beyond your requirements, unless you expect to sell your craft to the government...

As noted by others, keep the temp at 70 or above, use lots of clamps, mix per instructions and do not expect it keep strength in gaps ala epoxy. I pick warm days to glue; sometimes will keep parts in the kitchen when clamped (ah, bachelorhood...please, no safety lectures) or under an electric blanket. I am astounded how strong the joints are, even not working under aircraft mfg standards(wink).

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