West System epoxy

[BelgianPhil]

Hi,

I am using some West System 105 Resin with 206 Slow hardener. The specs say:
Cure to solid state: 9-12 hours
Cure to maximum hardness: 5-7 days

Does that mean i have to wait 5-7 days before i can scrape / sand it or is it fine once it is in its solid state?

Thanks

Phil

 

[custard]

When I'm using epoxy I put a very thin coat on a piece of scrap, once this thin coat has gone glass hard and scratch resistant I reckon it's safe to remove the clamps and do some light work like sanding or scraping, I'll leave it 24 hours before doing any heavy work.

It's important that this thin "test coat" really is very very thin. Epoxy cures faster when it's in a thick layer, so having an ultra thin layer go hard tells you anything thicker is sure to have also gone hard. Incidentally I also do something similar with Cascamite or UF glue, as like epoxy they're sensitive to the mixing ratio, so seeing the test coat go rock hard assures me I haven't messed up the mixing ratio on that particular job.

Good luck

 

[woodpig]

What are you using it for? I used to heat treat laminates made with West systems epoxies and cut and sanded it as soon as it cooled down.

 

[Beau]

Best to scrape it off when "green" this is a semi hardened state. It's like glass after a week and is tough stuff to scrape or plane but not bad to sand when fully hardened.

 

[BelgianPhil]

Thanks for the tips.

I'm filling knots/cracks in a couple of boards.

I have sanded a little bit and it looks good.

Phil