Themal Paste Shelf Life

[SiliconWizard]

I have a Noctua NT-H1 syringe that is probably 4 to 5 years old. Don't remember exactly. The official specs state that shelf life is 3 years.
Is it OK to use it in your opinion/experience?

[jpanhalt]

That's a paste of aluminum powder and zinc oxide in a petroleum base.
https://cdn-reichelt.de/documents/datenblatt/NOCTUA_NT_H1_SDS_EN.pdf

I would use it, assuming there are no big changes in its viscosity or color.

If you want to get rid of it, you could add iron oxide powder and make thermite.
https://en.wikipedia.org/wiki/Thermite

[SiliconWizard]

Yeah I suppose the only trouble could be if it had dried up. Although I don't know whether the aluminum could oxidize over time too.

As to thermite, interesting idea.

[jpanhalt]

Aluminum oxidizes almost immediately in air.  It is quite electrochemically active.  But, unlike, say iron, the thin oxide layer is protective.  That's the main reason aluminum is so hard to solder.  They The mixture is also protected from oxygen by the oil and by being in a syringe so the exposed surface is quite small compared to the volume, even if the syringe is not capped.

I bought my Kester solder paste in a tub and transferred it to all plastic syringes for that reason.