Grit blasting keel

davidportwain

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7 Mar 2007
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Rust coming through through the A/F on the keel, I have disc sanded down to metal on the spots, but I am wondering whether I should go the whole hog & have it sand blasted, then POR treatment then A/F

Advice please
 
If you have the time then dry-blast and epoxy bearing in mind the correct weather conditions needed to epoxy propely; if not spot treat the areas that you have ground down then hammerite and antifoul. When you have time do it properly with the dry-blast etc..
 
I have grit blasted spots on my steel boat by using a 2 HP air compressor and a spot blasting gun supplied by Machine Mart. The gun looks just like a paint spray gun, except that the can has grit instead of paint. The end of the gun has a rubber nozzle that is pressed against the spot to be blasted. After the grit has bounced off it is collected in a bag under the gun. This means that it is a very clean operation. The result is a 10mm diameter grit blasted circle.
 
Unless it's really bad I can't see the point. It will always be an on going saga unless it is epoxied. Grind it off, paint with Vactan or some other rust-converter (Vactan very good and cheap from ebay shop), 2 coats of underwater primer and the A/F. Touch up the bits that show each year.

If you have it blasted at Bradwell they will move you to a remote spot first to protect other boats. So add a lift into your budget.
 
The only way of properly removing rust is by dry grit blasting at high pressure. Any other method only puts off a proper job for a while. Steel has a grain and rust gets into it, grinding only removes the top surfaces and needle gunning tends to bang it further in.
Until a few years ago I owned a company which, among other things, was involved in major grit blasting contracts.
Ask yourself why do all the steel erection companies, the forces, etc. etc. pay the high cost of grit blasting if there is an alternative? Its filthy dirty and dangerous and would very quickly be banned on elf an safety were there another method of successfully removing rust. Then paint it, the paint is of far less importance than removing the rust.
 
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