What is the ambient temperature the jar/ container is stored at? normally higher ambient temperatures will make the viscosity thinner. also, when mixed it does thin out depends on how much hardener is used. remember it is a putty and not just an epoxy.What do you use to thin Devcon when it gets to thick in the jar?
Same issue after a few years, hard as a rock and unusable. Marine-Tex seems to be moire stable over time. I did a bed job last week with it that was at least five years old.I bought 5 sets of Devcon from a guy on forums. All well before their expiration date. All 5 unusable, so hard you couldnt dig it out. Tried heat, didnt help. threw it all away. Was shipped to me in the original 6 pack box with one missing. My guess is guy selling them tried one and it was bad so he sold the rest to my dumb a$$.
I use al devcon up to ten years old. They used to sell a thinner years ago. I called Devcon and the told me to thin putty with Acetone after it is mixed with the hardener, It works great.Try a little heat. Wifes hair dryer or heat gun. Dont cook it. Tommy Mc
Found this out by accident. You can make a mess but, it still set OK for me.also, when mixed it does thin out depends on how much hardener is used.