Prep/Paint Unfinished Crown Molding

I am having crown molding installed in a bedroom soon. The contractor dropped the crown molding off for me to paint it prior to installation. I stopped at my local paint store and purchased a good oil based primer and a good semi gloss white latex paint. I applied the primer and then after light sanding of the primer, painted the molding (after the primer sat overnight). After the first coat of paint was dry, I applied a second coat. Now the molding looks really good and smooth in some areas and in others is dull and really rough. Does anyone have any idea what caused this and what I can do from here? I am thinking of sanding again to get it smooth and then trying another coat of paint, but am afraid it will do the same thing after it is painted. Any ideas??

Thanks,

 

Either you have lap marks or the moulding didn't get sanded enough [are the dull areas a little rough?]

I wouldn't worry about it just yet. After the crown is installed, you should caulk and putty, sand lightly and apply the final coat of enamel.

If the enamel is drying too fast, you can add a tad of water [or a latex thinner like floetrol]. That should make the final coat flow a little better making it go on easier.

 

I agree. You most likely have lapping, which will result in the low sheen and roughness.

With your first coat of latex, you probably had a lot of working time, because it was over an oil based primer. The second coat would have set up much quicker because it was going over a soft, uncured first coat of latex.

Since you will need to fill the nail holes and caulk the crown in, I would wait and put the final coat on after installation. You may want to sand it smooth (and remove the sanding dust) prior to installation to make things easier.

On the third coat, you will may want to add some floetrol if the paint sets up too quickly. You are better off without it - if you can get the job done without it, but if you can't - it may be necessary.

Tip for the future: You are better off, particularly with trim enameling, to prime twice (with oil) and finish once (with latex), than to prime once and finish twice - with latex. In many cases, latex paints set up too quickly when applied over a fresh, first coat of latex - this method avoids this problem. When using this method, tint the primer to match the finish paint, so that hiding in one coat does not become an issue. Most of the time, the trim is going to be finished in white, so tinting the primer is not necessary.

 

Thanks much for the responses. Nice information to know. I think my main problem was I did not use tack clothafter sanding. I thought I could get by with vacuuming and wiping with a dry towel. I have since sanded and used the tack cloth. After painting again, everything looks pretty good. I am now a believer in using the tack cloth.
Thanks again!