Since when did PU-foam glues get widely available?

[charangohabsburg]

I'd like to attribute an approximately "maximum possible age" of an instrument, and one important detail would be to know since when PU-foam glues did get widely available.

It seems that PU-foam was developed in the mid 50-ies, but I have no idea if there foams were glue, and I guess that availability for normal people took place years if not decades later. But when, more or less? I'd appreciate just any hint, I'm totally clueless.

[DarwinStrings]

Hey Markus, the best I can help is that I first used it on a floor in London during 1988 But I am sure I had seen it in use before that.

Jim

[Kamusur]

Markus I hope some of this helps you but please forgive my ramblings if it doesnt.

AKAIK (disclaimer lol) There were/are 2 commonly used types of foam, Polyurethane and Polystyrene. Their use became widespread in the 60s as insulation in fridges, foam cored surboards covered with fibreglass reinforced resin (essentially a plastic and often known as GRP) and boatbuilding etc due to the inherent nature of their bouyancy (both foams have enclosed air cells in them they so float and can insulate as well)
They and their associated glues were developed at around the same time and are petro chemical by-products.
Polyester resin is compatabile with PU (urethane) foam and this foam is also easily sanded and shaped. Epoxy resin is compatible with Polystyrene foam which is not easily shaped/sanded and was often moulded.

Methyl Ethyl Keytone and Benzoic Peroxides (used in rocket fuel so safe to assume they were developed concurrently with the space race programs) were the common hardening agents in Polyester resin and mixed in the ratio of 1 litre base to 1%/10 ml hardener dependant on weather/ temperature/ humidity conditions. Polyester is/was generally considered to be more toxic and dangerous to use.
Epoxy resin was usually mixed at a 50/50 ratio. Polyester was the go to product as it was relatively cheap, epoxy was about 4 times the price in the early 70s and was claimed/known to be much stronger.
Glue, paint and plastics development began again earnestly in the 80s and we have even come to know these products, PU and Epoxies generically (think 2 pack) and these glues are usually mixed at a 2 to 1 ratio. PU glues can mimic those early foam products to a certain degree for example they may contain small air cells so can fill gaps etc (read dont clamp these glues so tightly lol)

Early Polyester Resins were developed as 3 types, Style 1 remains soft and malleabe when cured but can't be sanded. Style 2 remains thicker (and good for filling) and is able to be sanded. Style 3 remains glossy,thin and is also able to be sanded. They turned 3 distinctly different colours when hardener was added.

Steve

[charangohabsburg]

Thank you for your answers.

Jim, was this glue you were working with or PU-foam not specifically designed to be glue but rather a structural element and/or gap filler?

Steve, of course your shared knowledge and details are not only very interesting but also useful to me!

[DarwinStrings]

Yep Markus, It was a gap filling glue. I used it to glue secret nailed hard maple T & G flooring to a chipboard substrate that was screwed to a concrete floor. It was used to minimise (or stop) the T & G creak. I also made, at the same time a laminated skate board deck (lunch time project) and it held up well.

Jim

[charangohabsburg]

Thanks again Jim.
And yes, this glue seem to hold up very well over time. In the last four years I have removed more than ten fretboards from their necks, but this was the first time I had to chisel and plane one off!

[woodrat]

Hi Markus my first recollection of it was seeing Gorilla Glue advertisements in the American mag Fine Woodworking in the mid nineties and wondering what it was like to use...it was exotic then to Aussies as it was just another unobtainable from over seas. I got to use it when I mentioned it to a friend of a friend from the US and he sent me some on his return to the States in about 2001. About 10 years later it has started to turn up in Bunnings so that is about the average lead time for a lot of things from "the rest of the world"

Cheers Markus

John

[charangohabsburg]

Thanks for your very helpful input John!

Cheers,

[Nick Payne]

PU glue was first produced in the 1950s, but it certainly wasn't widely used. I did a lot of boatbuilding in the 1960s, and I can't remember PU glue being an option for boatbuilding as it is these days. The choice then was to use either resorcinol or epoxy.

[charangohabsburg]

Thank you too Nick. My picture is getting clearer with every additional comment.