What sort of Epoxy? Jotun 87 or similar is very thick - ideally brush or airless spray but they cost a fortune. I have just ordered a 2.5mm tip but will probably just end up brushing as you need a very thick film.
For Jotun 87 or 87A I've had good results with a 2.5 fluid tip and a gravity gun.
I thin with a maximum of 10% Jotun thinner 17.
Warming the paint helps as well.
It's probably not an epoxy mastic at this stage but it still gives a good thick coat and I have used it as a primer filler, like on this nose cone before welding the bits together and filling with bog.
It takes a while to dry fully hard but when it does it sands ok.
If it's not fully hard dry it clogs the paper a bit but there is no ill effects to the coating, I'm talking about the difference between overnight and it kicking about for weeks / months which is my normal way of doing things.
As with any epoxy, if it’s not overcoated within the recommended recoating times, it need to be sanded to ensure good adhesion between coats and the same goes if you are aplying filler over it.
The devilbiss FLG5 with 1.8 tip has really good reviews if you're looking to buy. I would recommend spray guns direct but other suppliers are available.
How does epoxy stick to galvanised steel ? I need to do a repair on sheet steel before painting it and all i can find in my little store is a perfectly sized piece of of galvanised.
Degrease with panel wipe and a sand with 120 or 180 production paper then panel wipe again and it will stick like s*1t to a blanket.
All the cars that are galvanised or zinc coated are primed with epoxy.