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Blushing/flat finish

Posted: Sunday, May 6, 2012 12:12 PM Quote
So just when I thought I got the hang of the Top Coat paint it turned around and Slapped me in the face.  I was feeling pretty confident having painted my fuse, two lower wings, cowling and all the metal parts with great results I decided to leave the biggest piece for last the Upper Wing.  The upper wing on my pitts is 17.5 ft with a 3 ft chord.  I mixed up the most paint I have mixed yet which was around 1 quart total.  I shot the 1st fog coat and thought may be I put it on to heavy it started to spiderweb on my in places.  I figured I would press on and see if it didn't show through.  I had to wait about 15 mintues for that coat to tack enough for me the spray the second.  This time though the spider webbing didn't get covered up like it has in the past.  I again had to wait like 15-20 minutes for this one to tack as well. So we are in 30 min already and I am not on the 3rd coat yet!  Once it tacked (sort of) I shot the 3rd coat.  It went on well but started to run in some place (first time I have had runs).  I waited almost 30 minutes for that to tack so no we are in 60-65 mins.  Mean while I mixed up more paint and shot the last coat.  This is where the runs really start, curiously around the where the spiderwebbing was.  So the last coat glossed up nice and to combat the runs i tilted the wing horizontal.

So 4 hours later I came back to a soft flat surface (not glossy) with some areas sort of glossy but some completely flat almost opaque (kinda looked like gasoline on the water in places) looking, and really soft (babies but so to speak) to the touch not glossy grip like the other surfaces finish.   I know the humidity was pretty high that day around 95% but I am shooting this in my basement and it was about about 71-72 degrees and the humidity is way different there and I am ejecting the air out of the basement.  So any ideas on what happened?  Here are the variables that made this job different.  As for the humidity I had good results 4 days earlier and the humidity was around 80-85% out side.

1) New gallon of paint
2) New quart of cataylst
3) Possible High Humidity
4) Rushed job not tacking well.  

As far as the correction to this I am starting with the following:

1) going to buy a humidity gauge
2) shoot a test panel to see if I get similar results (could be the paint maybe or catalyst)
3) Sanded down the upper wing smooth again
Posted: Sunday, May 6, 2012 10:27 PM Quote

I have completed the following:

1) Purchased a Hydrometer the basement today was at 70 deg and 68% humidity (not great)
2) I shot a test panel of the white it took forever for each coat to tack total paint job took 70 minutes and it still ran (sheeted) because it wasn't tacked (still slightly stick with some color transfer)  20 secs on the M50 cup
3) Thinking it was the white I shot some metallic silver  (20 secs on the M50 cup) I had on a test panel it tacked much much faster still ran and sheeted on me a little but the job was done in 41 minutes about 10-12 minutes for each coat versus 15-20 for each coat with still no where near the tack issues like the white has been doing to me (aka tacked a lot better but I probably should have let it sit a little longer)
4) Thinking it was the humidity I borrowed a de-humidifier and started that process and have the project a rest for the day in 4 hours It had removed 68 Oz of water from the air and had dropped the humidity down to 62%.

I will try another test panel tomorrow after work hopefully the humidity will be way down below 50% or more the lower the better in my mind.  I also may try shooting a test panel with the viscosity at 22-23 sec instead of 20.  I had been shooting everything at 20 because I was have was having a hard time with the blue flowing out and at 20 sec it really flowed out nice.
Posted: Monday, May 7, 2012 10:09 PM Quote
So update number three was that Stewarts tell me that 70 deg and 68% humidity was just fine and near ideal and  that my particular lot number of Part A white on the latest batch I received were likely bad and Stewart's immediately sent me a gallon kit to replace my bad lot.  I really appreciate the great customer service, and quick response!
Posted: Friday, May 18, 2012 1:34 PM Quote
So update #4.  I got my warrenty replacement white from Stewarts and shot that on to some parts.  It tacks up perfectly so the problems I had with the last batch was probably just a bad "lot" of Part A paint resin.  Glad that's behind me.  Thanks for the great support from stewarts I'm back in the game.