neighbor lending me sandblaster to do keel right now. any tips?

[luvitt]

i already osphoed the heck out of it and was just gonna paint over it. its rained everyday for a month. so now i got this blaster and i think its a good idea to do it. do i just blast it clean and barrier coat it as quick as possible? do i need to wash it after blasting? i know the rust supposedly flashes within an hour. should i do a section, paint, then move on? thanks

 

[caguy]

A high pressure water blaster is probably just as effective and cleaner. I did my trailer with a 3000 psi that I rented from Home Depot. When I told him what I needed it for he gave me a nozzle that they don't normally rent out. That took my trailer down to bare metal pretty quickly.
I believe with a sand blaster you have to use something besides sand to prevent the sand from embedding itself in the metal, which can lead to more corrosion.

 

[Mike Holibar]

For marine use it is usual to grit blast to Swedish class 2.5 gray metal surface, removing all old paint, rust and mill scale. It can help to wash with fresh water after blasting although usually the hull would have been blasted with fresh water when it came out. Flash rusting can occur more quickly in humid conditions, but it would be usual to complete the blasting before painting. If you rinse, a further light blast to remove any flash rust would be advisable. The ppurpose of the rinse is to get rid of any salt. Before you blast though, you need to have a paint system in mind. Altex Devoe make the best paints available in this part of the world and their system would comprise an inorganic zinc primer followed by an epoxy primer and then maybe one or two coats of high-build epoxy primer. After that comes the antifouling. There is a lot involved but if you get you surface preparation and priming right, you will have a durable paint system that will last for years. Filling and fairing compounds should be applied to the first epoxy primer coat and not directly onto the metal. Good luck,