Thursday, February 16, 2017

Crazing Paint? TIP

A builder posted this picture on Facebook. I'm not showing this to embarrass anybody. The information below might help somebody with their paint issues.

We've all been there. Imagine the frustration, especially on a build this complicated - The Estes QCC Explorer!
The builder had used Rustoleum 2X primer and followed with Rusto 2x Gloss White. As shown in the picture, the paint crazed.

I didn't post a response on Facebook.  Twenty others already had, some giving bad information. My answer would have just clouded the waters.
On response said this is what happens when you put lacquer over enamel, or vice versa. Not true! Lacquer will dissolve enamel but you can use enamel over lacquer.
Another suggested using a Dremel tool to remove the paint. A Dremel would be too aggressive and could even go right through the body tube.

Still another response was to simply wipe off the wet paint and start over. If you tried to wipe off wet paint you'll have a bigger mess to clean up. It's best to let it dry, sand it down and spray again.

The real problem here - the builder probably didn't read and follow the re-coat time instructions on the paint can. I always check the drying time recommendations especially if I am using a new brand of paint.
Most recently I had to use some Valdspar spray paint. I rarely use that brand but they had the color I needed.
The can specified the temperature and drying times. "You can re-coat within one hour or wait 24 hours before re-coating."
I would assume the builder painted again after the one hour. The new wet paint reacted with the drying paint and made it pucker up. If the first paint has started to "skin" over (half dried) a new wet coat will cause the crazing.

Notice how most of the wrinkling happened on the body tube, not on the balsa. Balsa "breathes" more so the paint dried faster on the wood than a sealed body tube would. Nose cones take even longer to dry!

Painting is a crap shoot. Some days it goes great! On another day, the paint manufacturers change the formula and you've got to relearn everything!


  1. That looks exactly like the problem I was having. Now I know the cause. Thanks for the info.

    1. Hi Bar,
      Sometimes there is other factors. Temperature and humidity can effect the drying times and quality of the gloss. It's always an adventure. It's a little difficult to press down on the spray can nozzle with your fingers crossed.

    2. I should add, different manufacturers (and different kinds of paint) have different recoat times. Always check the can instructions.

  2. I've had that problem myself recently; sometimes the paint just goes wrong. It certainly wasn't a lack of patience or lack of understanding of the instructions on my part. One of my Sprint up-scales took several retries because of crazing, bugs, various blemishes, etc. There was one particular spot where the paint blistered a number of times even after letting it rest for days after priming. Finally wound up sanding the whole thing down until it was pretty much bare tubing and started over. I have to keep reminding myself it's just a model rocket!

    1. Hi Tim,
      This post wasn't to say this is the only cause of crazing paint, it's more than likely the cause.
      Spraying in heat, humidity and extreme cold all effect drying times. Sometimes you think the paint is completely dry but underneath the dry skinned over top it could still be soft underneath.