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STEEL BOAT BLASTING AND PRIMING IN COLD CLIMATES

2001

We build 65-95' steel motor yachts in the cold Canadian climate. We use International Paint and Interlux [affil links] products. Rust prevention is obviously key -- especially on the crucial first coat.

The two yards we work with (in New Brunswick and Nova Scotia) typically sand blast the finished boats outdoors (often in dry cold weather in winter) then move them indoors to apply paint. The first coat is normally organic zinc on freshly blasted steel.

My concern has to do with flash rust and condensation. Does anyone out there know of any wash or other process that can inhibit flash rust and condensation after blasting? Any suggestions, product tips or pointers will be much appreciated.

Peter Sever
- Toronto, Ontario

My first thought is to spray phosphatize the steel. Your paint mfg. should be able to recommend the most compatible phosphate. ie: zinc, iron, manganese.

Dan Weaver
- Toccoa, Georgia
2001

If the steel or aluminum surface has been prepared to a "near white" condition by abrasive blast to a 1 to 3 mil profile(3 mil pref.) , the flash rust process may be retarded for 24-48 hours by application of a 5% sodium silicate solution. You might consider using a weldable rust retardant primer on the steel prior to welding on the hull and then doing a final blast prior to final anti rust coating with the organic zinc

Mike Mostello
- Drexel Hill, Pennsylvania, USA
2002