hi m carter
i've never used foma on canvas ( i do have a few KG of foma in the wings though )
BUT i do have a copy of the book " silver gelatin: a users guide to using liquid photographic emulsion "
it suggests using an alkyd primer and suggests it will fill in the pores in the fabric giving it a smooth leathery and
bright surface ... it also says if you want the texture of your canvas to show through, you can dilute it with white spirits.
it mentions the staples + tacks that are used to secure the canvas may cause contamination and they should be isolated + sealed
using a sealant ( silicon caulk ) after tacking to the frame ...
( you probably know this stuff already ... )
the book doesn't mention anything about archival-ness or durability. what do the folks at rockland say ?
i would imagine they might say something similar seeing they are similar ( kndasorta ) ...
if you call rockland's 800# the guy who answers the phone pretty much knows everything there is to know .. may be he can help.
( and knowing they are different emulsions you can make an educated guess ? )
good luck !