Five Star Painting Franchise

New Concrete

Do your homework on the concrete before painting it. Please don’t just apply the paint and hope it will stick – this will cause many headaches for you down the road. It is important to know if there were any kinds of concrete hardeners or membranes that were used by the floor finishers. If water beads on the surface, or etching the surface still doesn’t seem to work, then there was probably a membrane or hardener used in the concrete. Membranes can be removed with paint thinner, but hardeners must be removed with shot-blasting or some sort of bead-blasting. Please talk to the concrete finisher before proceeding with anything, as he will give you the best advice on what to do.

Muriatic Acid

Muriatic acid is sometimes used to clean surfaces before painting. The proper mixture is 1part acid to 3 parts water. Please use caution as we are dealing with an acid here – make sure that when you are mixing the two together (the acid and the water) that the acid is poured in to the water, and not the other way around. Heat is created in the mixing process, and foaming might also occur – just be sure that the solution does not splash onto you. Always be sure to wear the proper attire when mixing chemicals. Also, be sure to allow 72 hours of drying before applying any coat of paint to the surface.

Etching

Using Muriatic acid is a very good way to etch a floor. People often use mops to apply the solution across the floor. This causes heavy and light spots around the floor. Try using a plastic watering can in a criss-cross method instead. This method seems to work better for consistency. The mixture must sit for about 30 minutes, or until the fizzing stops. The surface must then be rinsed with water to remove the salts from the reaction of the acid and the concrete. Always be sure to use the proper attire when working with chemicals.

Curing Time for Concrete

Painting concrete before the moisture has left it will cause the paint to peel and lift as the moisture tries to escape. Typically, concrete cures after 30 days. However, there is still moisture within the concrete trying to escape for up to 60 days after it has been poured. Be sure to wait at least 60 days before painting new concrete.

Laitence

Laitence is a thin film of cement and sand that ends up on the top of the concrete when a machine has done the finish floating of a concrete floor. The mixture of Muriatic acid and water will remove the laitance, please refer to the ‘Muriatic Acid’ section for more instructions. You can also use any kind of etching solution to remove the laitence as well. Laitence sluffs off and makes the floor dusty. In fact, laitence is what is often found on the back of the paint when it has failed on a concrete surface.

Moisture Testing

Here is a simple moisture test to see if the concrete is ready for paint. Cut a piece of 4 mil plastic into a 3’ X 3’ square. Completely seal the edges with duct tape – make sure that it is completely sealed around all the edges. Allow it to sit for 48 hour. If no condensation forms, the concrete should be ready for paint. Sometimes, if the proper vapor barrier was not used when the concrete was formed, you might have continual moisture problems with that slab of concrete. If this is the case, the paint might not ever ‘stick’ properly.

If you have some concrete that needs to be painted, give Five Star Painting a call for a FREE estimate, 1-866-965-STAR or visit our website.