SW Pro Classic question

[Charlie McGuire]

I decided to use SW Pro Classic satin acrylic to paint my stair skirts. I never used the Pro Classic before. The skirts have been primed for weeks with an SW alkalyd primer.

The first coat went on fine and wasn't applied thick. The can said recoat in 4 hours.

Four hours later, I start the 2nd coat. What a mess! The stuff went on rough, and even using thin coat, it wants to sag and glob like crazy.

So now I'm confused - wondering what happened. Is the 1st coat still not set enough ?

Also, how to deal with the rough 2nd coat. Can I let it dry overnight and sand ?

Thanks,
Charlie

[Steve Flavin001]

been SW (Sherwin Williams) ardent user/fans for 40 - 60 years (my late dad before me ran a trade shop) and I have never had such experience. Let me look up the tech sheets and a couple of other sources on this - your note is very succinct and on topic. I will be back to you on Monday and look forward to pursuing this - I'll have some supplemental notes here too. :)

Steve Slavin, Concord, CA

[Steve Flavin001]

comments...

The four hour re coat bothers me in that their 4 hour timing might not have been adequate for your local conditions and the finish lifted the 1st coat. Your description appears to be that exactly of lifting prior not adequately dry, coat.

I assume you stopped at this point; by now the coat is dry. Be sure it is is thoroughly dry and then sand it with 120 paper or thereabouts as you suggested.

Try applying a test on scrap lumber - one sq. ft. or equivalent would be plenty. Allow overnight indoor drying between coats to be sure.

Then, let's discuss. good luck.

[Charlie McGuire]

Steve,

Thanks for your reply.

Yes, it did seem like the 1st coat was disintegrating as I applied the 2nd and I didn't keep going. When the sags and rough spots appeared, I dove in and dragged them out with the brush as best I could - trying to minimize sanding pain later. Conditions were 70 degrees and 40% humidity in the house.

Never having used this line of paint before, I didn't know if it was a drying issue or just a tricky line of paint to use. I really liked the way the 1st coat went on so I was hoping it wasn't tricky paint.

I'll give the 120 grit a whirl later today and retry.

Charlie

[Jason Roehl]

Charlie, based on the drying conditions you mention, the drying time should have been more than adequate. I've recoated in less time at higher humidity and a similar temperature. What you're describing could also be that you are overworking the paint. ProClassic waterborne does actually start to film over pretty quick, so you have to lay it on, get it where you want it, then tip it off and leave it alone--three strokes, in other words. If you're doing large areas, or lots of trim, use a 4" roller (foam, mini or 1/2" nap) to apply, then tip it off with a 100% nylon brush. I've found this to work well, but the key is to work quickly through an area--don't dawdle.

[Charlie McGuire]

Thanks Jason,

I tried not to dawdle, but have to cut along the stair treads/risers so that slows things down a little.

This morning I sanded yesterday's disaster and started again. It went on much better today - nothing like the globbing and sagging I was seeing yesterday. It still had a tendency to sag a bit, but tipping dealt with that.

Charlie