I was thinking of trying bomboo as a backing. I have a bunch of cherry,maple and hickory boards that I would like to try it on. I have seen both used but what's the best?

URAC is best in my opinion, both will work fine when used correctly.

I ordered some urac a while back but haven't used it yet.  Is it difficult to work with?  Any suggestions or tips that might help during glue-up?
I've used smooth-on many times and had great results with it. But I've read that urac has good "filling" properties for wood to wood application. Is that correct?

Red you are correct. Great filling properties.

I have only used urac and it's pretty simple use.

URAC gives you wayyyyy more time to work.

What I found about Urac though is that the liquid portion is difficult to measure accurately because it is so gooey.  If using a teaspoon or similar, measure out the powder first.  Then with the dry spoon, measure the goo and level off with a butter knife or like object.  Excess goo still stays on the underside of the spoon.  My first attempt was with a splice and it held up real well, though.  The filling properties were great also.  Make certain that the temperature you are working in is over 65 degrees.  A heating box would also benefit.  With my splice, I positioned a lamp above the splice which significantly helped my curing.  Without the lamp, it was not setting up.

I used TBIII on my last two BB backed Osage bows, with great success.  I gave it 3 days curing time and was sure not to starve the glue joint by excess clamp pressure.  I spread the glue on both surfaces and let it soak in for a few minutes first.  Then I added more glue to make up for what soaked in, then clamped.

Go to the bargain store and buy a cheap set of measuring spoons. I keep the corresponding spoon in a zip lock with the resin and glue. A lot less messy and makes measuring quick and neat.

Thanks everyone this will help.

I always measured Urac by volumn and not by weight. I used a stainless steel tea spoon and measured the dry first then the liquid.  Not as accurate but I never had a glue failure. Urac is very easy but you need at least 70deg(F) for it to set up and at that temp it takes at least 24hours. With a heat box you can do it in two hours.

I do as Pat does and I use a dual work lamp to cure it fast, no hot box.

I only use Urac-185 on my bamboo.
Unlike Pat I like to go by weight. I have a small grain scale. I save tuna fish cans for mixing.

Start with the liquid. tare out the scale after adding can. put in liquid tare out scale and add powder.
100 liquid to 13 powder by weight.
For one bow I usually like to mix
500 liquid and 65 powder. This is a youth size bow.

If it's cold I put one 100 watt bulb near form and cover with a blanket.
24 hours usually.
Good building  Ron

I swore off of titebond a long. long time ago. I only use urac for wood to wood, or wood to bamboo gluing, and I only mix by weight. I mixed by volume one time, and that was the last time. nelson paint co. says 100 to 13, but I always go 7 to 1. is much easier math to do it my head thataway. is very slighty "heavier" mix, but I have never, ever had a glue failure with this mixture of urac(indeed, never had a failure with urac in any circumstance), and it still provides a working time of 30 minutes, even at 80+ degrees. I also prep my glue surfaces with toothing plane or freehand with a toothing iron, and clean them with acetone.

I keep my urac parts in two glue bottles I got at a paint store. the kind that look like they might dispense condiments, with a conical spout. I also use a pocket grain scale and weigh out the components into small plastic "dixie" cups(about 4oz size, I think). just before I'm ready to spread glue, I dump powder into resin and mix. I've re-used the powder cup forever, mix glue in the cup with resin and throw away when done. no muss, no fuss, no clean up, except for the popsicle stick I stir glue with. been using the same one for 10 years. I'm rather attached to it now, I guess.  :D  

the ratio I use is nice because you can mix any amount of glue weight in grains that is divisible by 8. for a 64" flatbow I mix a total of 640 grains of glue(560 grains is cutting it close, and I'd rather have a little left than spread it too thin), that is 560 grains of resin, 80 grains of powder catalyst. for gluing on a riser I mix 160 grains of glue; 140 grains of resin, 20 grains of powder.

Thanks, guys.  This isn't my thread but I'll still benefit from it.

All I use is urac and I weigh it out just like macbow. Urac is bullet proof! I've never had a glue joint come apart with it. For a 66 inch BBO bow, I use 91 powder and 700 liquid. I may have a table spoon left over. I let the bow clamped up for 24 hours at 70 degrees. Urac needs at least 60 degrees to dry.

powder  liquid

13 ----        100
26 ----        200
39 ----        300
52 ----        400
65 ----        500
78 ----        600
91 ----        700

I use about 500gr of liquid for a glue-up with Urac. If you use a metal handle glue brush to spread your glue it takes a lot less.



A friend called the Nelson Paint Co to see if there was an optimum liquid/powder ratio. The tech rep said you could put about any ratio of hardener in the mix and have the same bonding strength.

Will the Urac work if you have a fiberglass accent strip in it?

I do not believe urac is a good glue for glass.

I agree would not use Urac for fiberglass. Go to smooth on for glass.
Ron

I have some Urac that I bought a year ago, it has not been opened and has been kept in a dry cool place. Do you think it is still OK? Bue--.

Your glue is OK Bue. If you open it and it has black flecks floating around in it, it is probably bad. You may see a little rust in the glue from the can but that is OK.