use or used?

Used.

A case could also be made for "had used."

Thanks, Frank!

The superglue solvent in the bottles evaporated even before I had used it.

Should the first "had" be removed? I think there can't be two "had's" in the same sentence.

Yeah.

The reason I used the expression, "A case could also be made for 'had used'" was because of the adjustment of the sentence.

There is a tiny bit of nuance between, "The superglue solvent in the bottles had evaporated even before I used it" and "The superglue solvent in the bottles evaporated even before I had used it."

The sentence actually makes more sense if written, "The superglue solvent in the bottles had evaporated before I had a chance to use it."

The addition of the "a chance" eliminates the need (in answer to your original question) to use "used" or "had used."

The thought you were attempting to convey was that you had some bottles containing superglue solvent. And before you had a chance to use the solvent...it had evaporated.

The original thought contains an implied, "I had some bottles with superglue solvent in them...".

Essentially, "I had bottles with superglue solvent in them, but the solvent had evaporated before I got the chance to use it."

There's no evidence of anything being said in the story, let alone it being said "then and there". Was the person fond of talking to themself in antiquated idiom?

Top marks for planning and punctuality though if the person knew that in precisely one hour they wanted to use the solvent.

Should it be "themselves"?

Thanks!

Only when it's a twofer like Miss Koh Elaine and Miss Tan Guat Lay.

So it should be"themselves", right? Or should it be"themself"?