Some sheet films still have excellent tooth, some do not. Traditional photo sprays were typically based on butyacetate lacquer - quick drying but not very healthy. Now you can go to the art store and get an equivalent acrylic spray for the base side of the film to give some tooth, but all such techniques are a bit risky, messy, and probably non-archival. You can also simply register a sheet of frosted mylar and do your retouching on that, for any format, if you don't want to tamper with the original neg. Red creosin dye takes some patience to find, but a little bottle of the dry powder will probably last you a lifetime. But there are all kinds of pen and pencil ways to do things. It's interesting to haunt
used bookstores on rainy days, where the guy at the counter is himself covered with cobwebs, and thumb thru the section of photo books.
You often find old Kodak graphics and photo manuals with all kinds of these forgotten techniques illustrated.