Sodium Thiocyanate hard as a rock; still good?

[Kino]

Question as stated. The container was well sealed, but it has formed into a solid mass.

Still viable for photo chemistry if ground up with a mortar and pestle?

 

[Agulliver]

Almost certainly it's fine.

I use kilos of the stuff per year in school laboratories and have 10kg containers. It tends to form the hard clumps as you describe. Always works in chemistry lessons and I have.....appropriated small quantities to make my own fixer which seems very potent (clears film in under 45 seconds).

I tend to chip away at it with a large metal lab spatula.

All that is happening is that the crystals lose their water content and sometimes reabsorb from the air in the conteiner and that's when it clumps into very hard rock-like pieces. Chemically it's fine.

 

[lamerko]

It is hygroscopic, moisture has probably penetrated, which is why it has hardened. It should be fine, but you may want to take this into account when weighing it…

 

[Kino]

Almost certainly it's fine.

I use kilos of the stuff per year in school laboratories and have 10kg containers. It tends to form the hard clumps as you describe. Always works in chemistry lessons and I have.....appropriated small quantities to make my own fixer which seems very potent (clears film in under 45 seconds).

I tend to chip away at it with a large metal lab spatula.

All that is happening is that the crystals lose their water content and sometimes reabsorb from the air in the conteiner and that's when it clumps into very hard rock-like pieces. Chemically it's fine.

Many thanks. I thought it would be so, just wanted confirmation. The mass is still white and crystalline, it just appears to be "clumped" together.

It is hygroscopic, moisture has probably penetrated, which is why it has hardened. It should be fine, but you may want to take this into account when weighing it…

Good point. It was given to me in the original Photographer's Formulary bottle with tape around the bottle seal, but I guess the plastic bottle is only good for a limited storage time. I will move it to a glass container.