Assuming you are refering to a cementitious SFRM (Grace Monokote, CAFCO Blaze-Shield, etc), then paint is a no-no. If you are refering to an intumescent coating as Steve referenced, then priming is required, but usually limited to certain types of primers.
The removal of loose mill scale and surface contaminants is generally required before application, so that the bond between the coating and the steel is not compromised, whether it is the direct applied SFRM or the primer for an intumescent coating.
Ron,
So, for the cementitious SFRM it is a no no and for intumescent it is yes. Why?
If corrosion is a no problem then priming should not be required in either case and if it is bond problem, I think the SFRM doesn’t provide corrosion protection. Do you prime steel not receiving fire protection in a non corrosive environment?
As apsix noted, intumescent coatings are paint...they require priming. Cementitious coatings bond better to steel than to primers. Cementitious coatings also provide passivation of the surface of the steel, thus inhibiting corrosion.
I believe there are primers/paint that will bond with fire proofing. Just ran into a case where the GC wanted to prime all the steel (whether it received final fire-proofing or not) b/c they didn't want to run the risk of rusting due to exposure during construction.
