Guys,

Im picking up some sierra rear calipers tomorrow and tey need a clean.

Can i safely submerse them in parafin for a few hours to help the degunking process?

Only if you are renewing the seals & dust seals, as the parafin will damage the rubber.
Cheers
Ian

bugger,

Im lead to believe they are perfectly servicable items that were working jsut fine when they were taken off the sierra last week.

Only problem is that they are a bit dirty...........anything else i can soak them in?

Are you planning on painting them?

If not, you might as well save some money from having to refurb them and just use a bit of caliper cleaner spray, and a bit of scotchbrite to clean the larger, visible surfaces.

Unless they look like this, I wouldn't bother with anything more than necessary:
Rescued attachment Rear Calipers.jpg

planning on painting them to be honest. i might tackle them with some degreaser and scotchbrite.