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Urea glue and vacuum press12/24
I have to laminate some curved wood work and I want to use a vacuum press for that. Now I have seen on the forum that urea glues are the best for the job because of zero creep and rigid glue line.
My question is now since I can not find a definite answer in the knowledge base or forums is that is any UF glue appropriate for a vacuum press because I am from the Netherlands and the only source of UF glue I can find here states that the minimum clapping pressure is 30 PSI and the clamping temperatures are stated from 158 degrees fahrenheit upwards for a 9 minute clamping time. I have seen on the forum that many people use unibond 800, that is formulated to work in a cold vacuum press if I am not mistaken, but I can not order that here.
Dap PPR glue also states in there documentations that the glue needs a minimum pressure of 50 PSI clamping pressure, but I know that many people use DAP PPR glue in a vacuum press and maybe add a bit of temperature by using a heating blanket to speed up the cure time.
So in my understanding urea glues work fine in a vacuum press even when the manufacturer states that an even higher pressure is needed. Higher temperatures when clamping only shorten the curing time.
Is this an correct assumption and could someone maybe corroborate on this. As I have to buy a 66 pound bag of the stuff as they do not have smaller quantities.
Thanks for any information and happy holidays
We just did a job that ended up looking like an oscilating wave. It was glued up withe 6 layers of 1/8" fin ply. We used
Elmer, I have used Urea for many years. You will find that it has excellent holding properties and does not creep as do most glues. It can be purchased in local yards or large home suppliers. It works excellent in vacuum bags so don't be afraid of a possible failure. I can't imagine having to buy a 60 pound bag!!! It goes a long way and if not kept in an air tight container it will go bad. Don't buy more that you can use in a reasonable time. I have bought it in gallons cans and that will last you a very long time. Contact me if you need advice mixing it. Over time I have come up with a better way of mixing than what the instructions tell you. Good luck!!!
Thanks Daryl and Snaglpuss for your replies. I am sure now, I can buy a bag of urea glue and not spent it on something that will be useless. And I really have to buy a 60+ pound bag (well 30 kg, here) because items that are very common place in the US are not very common in the Netherlands unfortunately. Here in the Netherlands there are only 2 suppliers of urea glue and they both sell in 30 kg bag (or 66 pounds) because I suspect that is the size they get from their suppliers. Well the glue is actually not very bad value for money because I have to pay the equivalent of 130 dollars for 66 pounds, I have seen on amazon dap weldwood 5 pounds of 27 dollars. But there remains the issue of how long I can store it, as long as it is not in a warm and or humid place it should be good for a year apparently.
With the remaining glue I could maybe make some, what we call here, multi plank floor it is a multiplex base with a solid wood top layer so it looks like a solid piece of wood flooring
I'm a little confused...
According to what I've just read, vacuum bagging delivers about 12lbs per square inch. How is this meeting manufacturers recommended clamping pressures of 30 to 50 PSI?
I know a lot of guys out there are using vacuum bags to laminate not only veneers but flat-sawn sandwiched boards and everything in between. These types of glue-ups often have recommended clamping pressures of 500lbs or more. What's the story, am I missing something here?
Admittedly, I'm the only woodworker I know that doesn't own some kind of a vacuum bag system (so I'm completely ignorant). Still the math doesn't seem to add up.
And sorry in advance for any perceived hijacking.
Jim, That was my first assumption also but dap weldwood ppr glue states in their technical notes that a 150 PSI is even needed but apparently according to the replies I got here and the info I have found is that any urea glue will work with much lower pressures than stated by the manufacturer. Maybe it is because the manufacturer states pressures for making purely multiplex sheets and maybe much less glue use and with much less glue the parts need to be in very close contact with each other to make a proper bond