What causes paint to crack?

Question

Around 10 months ago, we painted various rooms in our home, each in a different color. In two rooms we used paint from company X, and in another room we used paint from company Y.
Both companies are supposed to be good.

In the rooms with paint from company X, we have observed the following: a crack in the paint, and a strange drippy look (as if someone had added a darker shade over the paint, and it had dripped - or like someone washed the wall with some liquid and left a mark).
In the room with company Y paint, everything looks great.

My question is, could the crack and drippy look indicate that company X sells bad paint? Or is something else is to blame? What could cause cracks and a drippy look?

We are amateur painters, but I really thought we did a good job :-(

The problems all occur on external walls. Coincindence, or something more sinister?

Answer 1

Sounds like either of two things, or a combination of both. Inexpensive paint, or poorly insulated walls. You said the exterior walls only had the striping? It's called moisture wick, usually occurs from burning candles, cigarettes, ETC. Because of a lack of insulation moisture collects on the interior side and the smoke carries "dirt" particles to this moisture causing striping. You can paint and paint, eventually the dark spots will re-appear until you insulate and make sure the insulation has a vapor barrier
Is the paint spider webbing, or cracking? This is due to a lack of binders in the paint. Usually less expensive brands cut back on the pigments and binders to cut costs.

Answer 2

I think the paint is the problem I use only one brand of paint and I paint quite often. I never get cracks or peeling.

Also, if you painted in the bathroom, humidity can affect the paint.

Another thing, when you prepared the walls did they have cracks originally? Because if they did that might be your problem as well. Its important to seal any cracks or holes before you paint.

As far as the stain or mark you described, you may have a had a stain, like grease for example and if you don't use a primer all stains will come thru....Hope this helps.

Answer 3

You most likely used two different types of paint. Example: If the walls were painted with glossy paint (slick surface) and you used a semi-gloss or flat paint over it it will cause the new paint to run, or look odd. Always sand old paint to ruff the surface up to help the new adhere better. If you are painting over a darker paint then you also need to use primer first. Primer keeps dark paint from bleeding through. If you are painting over wood...it seals the wood so it won't soak up all your paint. Wood is porous (meaning it soaks up paint like a sponge). Cracking can come from moisture, or painting over wet paint before it totally is dry. Was the paint on the wall cracked before you painted over it??? If so you need to use a metal brush and sand paper or a putty knife to scrape the cracked or checkered paint off the area before sealing it with a sealant. Check with your paint store and see what they tell you. This should help you out, if not cure the problems your having. And yes, old paint can cause problems as well. Oh, if you are using latex paint... use latex sealer, if you are using oil base paint use a oil base sealer... if you do this it will adhere better. It could be that you may need to wash the walls with warm soapy water, then rinse. YOU MUST DO THIS FROM BOTTOM TO TOP OF WALL or you will have streaks in your paint. Good luck!!

Answer 4

could be the walls had a paint that reacted with the new paint, or dirt..grease. We had an old house with many paint layers and had to put down primer first.

Answer 5

humidity,maybe not mixing properly