Learn The Causes and Remedies For Chalking Paint
A fine, light colored, powdery residue on painted exterior surfaces of your home is chalking paint. This is normal and how all paints wear over time and is considerably better than peeling.
How do you know if your exterior paint is chalky? Easy, simply wipe your hand across the surface using a little pressure. You can use a colored rag instead of your hand. Choose a dark rag for light paint colors and a light rag for dark paint colors. If some of the pigment comes off, usually a light color when compared to your existing paint color, then your existing paint is chalking.
The primary cause is exposure to sunlight.
Ultra violet light breaks down the binders in the paint and releases the pigments. Another cause is a reaction between the binders and oxygen, this is paint oxidation. Both of these processes occur simultaneously and have an effect on all types of finishes.
While all of this chemistry is happening, the paint sheen will become progressively duller and the paint film thinner. The paint film thins from the effects of rain as it washes away the chalking paint residue.
Other Causes and How to Prevent Chalking Paint
Two more aspects of this problem is the type of paint you choose and its quality. Although all paints will chalk over time, some types have a tendency to chalk sooner.
Alkyd paints, aka oil base paint, oxidize faster than most acrylic and latex paints. In most cases, an acrylic paint is a better choice for exterior painting.
Another aspect is the quality of the paint. A general rule is “the more expensive the paint the more and better the resins it has”. The resins are the binders that hold the pigment. When they degrade the pigment is at the surface and appears chalky.
Cheaper paints will degrade faster. An example is exterior 100% acrylic paint verses a latex paint (or acrylic/latex combo paint). The best exterior paints on the market are 100% acrylic, not latex.
Removing the Chalky Residue
This powdery residue must be removed and possibly primed before applying any finish paint. The rules are very simple.
- To remove the residue use a pressure washer and mild, environmentally friendly, soap. Most pressure washers have the ability to dispense cleaners while washing. Use proper pressure washing techniques. Allow the soap to sit on the surface for 10-15 minutes then rinse completely. Repeat the rinsing until all soap residue is gone. Keep the pressure at 1500-2000 psi.
- Allow the surface to dry completely, usually 24 hours. If the amount of chalking paint was excessive or a lot of residue still remains on the surface you will need to apply a quality primer that is appropriate for your application. In most cases an acrylic primer will be a better choice with a severally chalky surface.
Don’t be overly concerned if a little residue is still on the surface. Chances are some will remain, even if you physically scrub your entire house.
6 Responses
How do you fix chalking on interior paint in your house?
Same basic principles as exterior chalking paint; clean the surfaces to remove as much residue as possible, seal the surface with a universal acrylic primer, then paint. The acrylic primer has the best chance to bind or glue the surface sealing up any remaining residue and providing a good foundation for painting.
My house was new in 2012. Should it chalk so quickly? It’s very patchy and spotty as if rain has fallen on it. Poor paint or poor preparation?
I see this all the time; Whole subdivisions go up really fast then in a few years every home needs a paint job. Just enough paint to sell the home.
Cheap paint and cheap paint job. Sounds like your home is ready for its first real paint job.
My house is a 1974 block stucco exterior in central florida. I’m not sure the last time it was painted but upon pressure washing the stucco the paint was coming off like milk. I think the paint was so old and degraded it was dissolving as i pressure washed. I followed instructions on pressure washing but the paint just kept coming off. I was advised by Sherwin Williams to get as much off as possible. So I continued to pressure washer the whole house and about 90% of all the paint came off and I’m down to bare stucco. Some area’s were not as exposed so the paint didn’t all come off. The remaining paint still has some chalkiness to it. My question is how should i proceed with painting/priming/sealing? I’ve read a lot about using a sealer here in Florida but not sure if I need it for the chalkiness. if so what kind? I’ve see a lot of people using Seal Krete in Florida or Loxon. If Seal Krete is fine I’d prefer that for the price point over Loxon. I’ve also seen FLood EMULSA BOND to add to the paint/primer?
At this point just prime and paint. Check out- painting Stucco for more info. You can use Loxon, doesn’t need primer apply 2 coats for best results.
I would get a good acrylic masonry or exterior general use primer, apply it to the entire house, fix cracks and caulk everything is, then get a good exterior house paint. You can also use Sherlastic elstomeric from Sherwin Williams, 2 coats back rolled.
Seal Krete is a clear sealer, although you can use it as a thin penetrating primer. Personally, I would just get a good primer, pound it on for a good seal (apply lots and work it into the pores and cracks with a thick roller), The remaining chalkiness will be sealed into the primer. Then apply a good exterior paint like Duration or coating like Sherlastic.
For a really cheap paint job; Mix the Seal Krete with exterior paint (50-50 mix) and spray 2 coats. Not the best way to go but will work in a pinch and could be considered a primer for later painting.