Why does paint stick to wall?

Answer 1

There are three main ingredients in any paint:

1. solvent ("carrier"),

2. color,

3. and film-former ("resin" or polymer).

Solvents are liquids (alcohol, toluene, water, etc.) which carry the color. Nowadays, most paints are water-based, meaning that their solvent is mainly water. Color is added with either dye or pigment. More often pigment is used because it lasts longer. Finally, resins are added which give the paint various characteristics, including how the paint flows, dries, how smooth it looks, how it sticks to different surfaces, etc. Resins are polymers which come in all shapes and sizes; some are natural like gums or starches, and a lot are synthetic like acrylic polymers used in house paints. Other stuff that is added to paints: fillers like clay or opacifiers (make the paint hard to see through), surfactants (chemicals that help stabilize the paint so it lasts longer or brushes easier), "antimicrobial" agents (keeps bacteria and bugs from growing in water-based paint), etc.

By pushing the brush to the wall you apply a force. The paint is pushed to the wall and will be in touch with the wall. Due to the resin, the paint has a high visco-elasticity, which means that it can be streched without breaking (like bubble-gum). By pushing the paint to the wall and move the brush along the wall, you 'strech' and 'scratch' the paint from the brush onto the wall. Surface tension also plays a role: liquids, like the water used in paints, always want to minimize their surface, hence want to form droplets. However, the paint is pushed onto the wall and needs extra paint from the surrounding area to form droplets. So the paint on the wall attracts extra paint(water) from the brush to be able to form droplets on the wall.

In regards to how paints dry on a molecular level: imagine that the resin exists as tiny drops in the water surrounded by tiny surfactant molecules. Also imagine the pigment as tiny (particles) in the water surrounded by surfactants... Once you brush paint out onto the wall, the resin droplets begin to lay down onto the surface as the water or solvent begins to evaporate. The resin droplets then "coalesce" or migrate closer together and bind (stick) to each other. The pigment particles begin to stick to the resin. The resin droplets eventually fuse together into one long polymer film on the wall, with the pigment particles trapped and stuck in it.

Answer 2

This past weekend I painted the interior brick wall in my bedroom. In the winter, the room is cool and never gets above 64. I live in Michigan and it got into the mid-teens overnight. When I went to pull off the blue edging tape where the wall meets the carpet, it pulled off the new paint! The wall was cold to the touch. I had primed the wall with Kilz and had painted using Glidden. The paint can said that the temperature should be 50 or above. I do not know what the temperature of the brick wall was when I painted.

I currently have a space heater in the room and the door is closed. My thought is that the warm room will cure the paint that is on the wall and warm up the bricks. Time will tell, it is 14 degrees outside. If I had to do it again, I would wait until it warmed up outdoors. If I was forced to paint (?) I would warm the brick up first and keep it warm until the paint had cured.

Answer 3

Paint initially sticks to the wall or other substrates (paintable surfaces) due to the ionic bonding that exists between the wall and the paint. As paint begins to dry, then the properties of the paint come into play and allow the paint to adhere to the surface.

Answer 4

Chances are, the wall has previously been painted with an enamel paint, and latex paints do not adhere to enamel. Only more enamel paint will adhere. But there are many different materials that can appear on the surface of a wall, and so there can be more than one kind of problem with painting. Sanding can be very helpful for some types of nonporous surfaces such as polyurethane.

Answer 5

Paint will stick to a wall with white wash. You will have a better experience if you apply a primer first.