The question ‘How soon after grit blasting do I need to paint?’ is actually a bit of a misnomer. The generally accepted industry standard is that coating takes place no more than 4 hours after completing the blasting process.
But time only plays a part in that. Surface and environmental conditions should also be considered. How quickly your paint is irrelevant if the conditions for coating are not adequate.
Benefits Of Painting In The Right Conditions
Grit blast surface preparation ensures that a metal surface is in an optimal condition to be painted to ensure maximum durability. The durability of a coating can briefly be considered as its Life to First Major Maintenance – this is typically 15+ years since the surface has been grit blasted adequately prior to coating and done so in the right environmental conditions.
A freshly grit-blasted surface will immediately begin to react with the oxygen and moisture in the air to form rust. If the surface begins to deteriorate rapidly, this is known as flash rusting.
Flash rusting is indicative of high humidity or the presence of surface salts. Except for very limited cases (such as surface tolerant primers), if you coat over rust or salts the surface will continue to corrode underneath the coating, defeating the purpose of coating in the first place.
Summary
During and after grit blasting, ensure that humidity is low. Ensure there are little to no surface salts present. If flash rusting becomes apparent, you should re-blast in the correct conditions.
The longer you leave between grit blasting and painting in the wrong conditions, the more likely the surface will deteriorate and the less durable the coating will be.
Next Steps
KUE Group has all the facilities to ensure that your items are prepared and coated in the best environmental conditions.
Call 01274 033120 to contact us for all your professional surface preparation and coating requirements.
