Epoxy putty

[jonboy]

I have a large , expensive drum of two part epoxy which wasn't closed properly and has gone very stiff from I guess solvent evaporation.. It hasn't chemically hardened and still works with the catalyst. What's a suitable diluent or thinner to make it more plastic/ sloppy / useable...?

[P.L.Lenihan]

Contact the company directly for proper instructions.

[Tom Lathrop]

I have a large , expensive drum of two part epoxy which wasn't closed properly and has gone very stiff from I guess solvent evaporation.. It hasn't chemically hardened and still works with the catalyst. What's a suitable diluent or thinner to make it more plastic/ sloppy / useable...?

Since no one else has chipped in, I will. First, epoxy does not work with a catalyst nor does it usually incorporate solvents.. It is a two part system in which each part is a chemically linked part of the final product, usually in ratios of 1:1 to 1:5. Neither epoxy resin nor epoxy hardener will harden by itself in a container but may start to do so if both parts are left in close proximity with open tops.

Conversion of polyester resin to a solid will take place with or without a catalyst but the reaction is faster when even a small amount of catalyst is added. Polyester resin will harden in a closed drum with no added catalyst if left for a long time and may thicken to a jell in the interim, depending on temperature.

Does either of these match what you observed? Others may have other explanations but both of these situations have been seen in my shop.

[jonboy]

Excuse me for not getting the terminology right... I think you have it as it is a couple of years old, but I am sure it hasn't been near the hardner, so I suppose it must be a thickening with age.... sounds familiar!
still, any chance of thinning it without upsetting the efficacy of the product.

It is polyester resin.

[AstoriaDave]

I suppose it must be a thickening with age.... sounds familiar! still, any chance of thinning it without upsetting the efficacy of the product. It is polyester resin.If it is truly polyester resin, it is toast. Over time, it will self-polymerize, without the aid of a catalyst. In contrast, the hardeners in epoxies do solidify if allowed to set at a cool temperature/ However, this does not represent loss of teh hardener. All you have to do is re-warm it.

Polyester resin does not need another component to polymerize. The catalyst just speeds up the process.

Thinning the resin will not help.

[Tom Lathrop]

If it is truly polyester resin, it is toast. Over time, it will self-polymerize, without the aid of a catalyst. In contrast, the hardeners in epoxies do solidify if allowed to set at a cool temperature/ However, this does not represent loss of teh hardener. All you have to do is re-warm it.

Polyester resin does not need another component to polymerize. The catalyst just speeds up the process.

Thinning the resin will not help.

Dave,

I'm sure you just misspoke and know the answer. Epoxy hardener does not solidify on the shelf, it's the resin that partially crystalizes in cold temperatures.

[James McMullen]

It is polyester resin.

Then it is done for FG lamination purposes. Sorry.
Please use the correct hazmat procedures for disposal, don't just send it to the landfill.

[AstoriaDave]

Dave, I'm sure you just misspoke and know the answer. Epoxy hardener does not solidify on the shelf, it's the resin that partially crystalizes in cold temperatures.Yup. Doh! :o :)

[jonboy]

As I said , as for now it still works, just that it is difficult to mix in the hardener evenly, and, not being so 'sloppy' it isn't quite so sticky, just have to use it up as needs must, filling teeth, that sort of thing....