I was cleaning mirror box foam with a q-tip for years until a speck of dust ruined a whole roll

I was working on an old Nikon F3 and used a dry q-tip to get the old foam out of the mirror box, like I always did. A tiny piece of lint must have fallen onto the focusing screen, because the next 36 shots all had this weird soft spot right in the middle. Do you guys use a specific solvent or a different tool to avoid this mess?

4 comments

4 Comments

kaigibson2mo ago

That foam turns into sticky goo when it ages.

caseythompson2mo ago

Yeah that sticky goo phase is the worst. It gets on everything and just smears around. Total design flaw if you ask me.

cameronp472mo ago

Tell me about it, right?

paulw531mo ago

Actually that foam turning into goo thing only happens with certain types of polyurethane foam. The cheaper stuff from like 20 years ago breaks down way faster than the newer formulations. The newer closed cell foams hold up a lot better and just get brittle and crack instead of turning into that sticky mess. I had to rip out some old foam from a boat once and it was like handling melted glue. But the stuff I put in last year still looks solid. So it really depends on what brand and type you bought.