If Mag Flake hardens in bag?

[dmbnpj]

I bought a bag of Mag Flake over a year ago and I have kept it outside in my shed since I first used it. I recently needed to add magnesium and realized I was out of my magnesium solution. I found the bag of Mag Flake in my shed solid as a rock. I can chisel a chunk of it off and use it to make the solution with some epsom salts. Would this be a bad idea for any reason because it is now solid?

 

[Randy Holmes-Farley]

It is fine to use even after hardening. Mine has hardened as well. It is just moisture getting into it, dissolving a bit and adhering chunks together.