West standard resin with the slow hardener is allready quite runny.

I find it will soak right through thin veneers (I use it to glue on wing skins onto foam cores) at room temps, so I have not had a cause to thin and/or heat it.

The resin and hardeners will thicken over years, as West sytems is good for many years shelf life it may be necessary later on. I buy mine in gallons and use it fast enough as fot that not to be an issue. If you will not use it up in a year or two you may want to get the quarts instead. I find the fast hardener is thicker than the slow, and ages a lot faster also.

AJC