Formamide is often used during hybridization. Each increase of 1% in the formamide concentration lowers the Tm by 0.7 degrees. I never came across DMF in blotting protocols.
Stripping is usually done by "boiling". I will just c/p the protocol of the Grunstein lab:
"Stripping Southern blots:
- do not allow membranes to dry out between hybridization and stripping
- make up 2L of strip solution (0.1X SSC, 0.1% SDS): 10ml 20X SSC 10ml 20% SDS 1,980ml water
- heat wash solution to 90-100°C
- add 1/3 to filters, incubate for15 minutes on rotating platform, with perspex cover over tub
I use NBT/BCIP detection and cannot find a protocol with the volume or concentration required for the DMF, do you happen to have one ? I'm using ROCHE manual for DIG-labelling but it only says to use DMF and does not mention how much. :/