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Remove tin oxide from steel surface
(-----) 2006
My customer wants to coat tin coated steel with a UV coating. The UV coating sticks to sand blasted and pretreated steel but not to tin coated steel. The tin on the surface seems to be easily removed. After further investigation I have found that this surface is tin oxide that is easily removed by applying tape to the metal surface. Is their an easy way of removing the tin oxide from the surface? The customer is cleaning by hand and would like to use a cleaner or acid or base solution. Is this possible?
Donald HartMid-America Coatings - Pittsburgh, Pennsylvania, USA
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2006
Soak the tin plated steel in hot (80C) sodium hydroxide solution (2N) with about 10 g/l sodium nitrite in it. This is the principle of detinning steel and works well. It will also leave the base steel very clean. Depending how the tin has been applied, you may see a dark grey colour - this is the tin-iron alloy and is slow to react, but it will do with patience. The process can be speeded up if you put the tinplate in contact with stainless steel in the solution - it forms a galvanic couple. Be very careful with the solution - it is very caustic and potentially quite corrosive.
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
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