Technical Advice

What happens to painted surfaces that have been submerged?

Painted surfaces that have come into contact with large volumes of water react in different ways, depending on how long they are immersed and how much water is absorbed.

Typically, for plasterboard, timber and cement sheet, the substrate expands and swells initially, and then shrinks once the water withdraws. Decorative coatings are not designed to withstand total immersion, and blistering issues generally arise due to moisture being trapped in the substrates behind the paint coatings.

Coated steel and other metals corrode when immersed in water, and this process is accelerated if these substrates are subjected to total immersion conditions.

Determine if the surface is sound by conducting an adhesion test on all previously painted surfaces. Prepare affected surfaces by scraping off all loose and flaking paint and ensure surface is dry.

Conduct an adhesion test

Ensure that previously painted surface is sound by conducting an adhesion test. To do this, cut a small X through the existing paint with a sharp blade. Press cellulose tape firmly across the cut and then rip the tape off. If the paint comes off, it is unsound and should be removed. Repeat the adhesion test at random across the painted surface, to thoroughly test the soundness of the area.If you are unsure that the substrate is sound (dry and undamaged), please contact a qualified tradesperson. In addition, please remember that the product information provided here is to be used in conjunction with the recommended product label instructions.

Once an adhesion test has been conducted, property owners can determine which parts of their homes can be repainted, and which areas require surfaces to be replaced. Here is some quality advice and product recommendations to successfully painting both weather affected surfaces and also brand new surfaces.