Home Forums Technical Support Fabric Finishing my experience with Stuart Waterborne Polyurethane (premium)


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  • ericklee64@gmail.comericklee64@gmail.com
    Post count: 3

    I am writing this with the hopes of starting a conversation in order to learn more about these topcoats and also to log my first experience using (tennesee red) topcoat over single part white eko primer.

    The white primer, I sprayed with a 1.5 nozzle on an astro pneumatic HVLP gun from Amazon ($96.00). No thinning. Just a lot of stirring to get most of the solids in solution. It was easy to apply, getting a nice even white over the grey ekofill after 4 1/2 coats.
    I sprayed with my volume set really low. I expect I was a little over cautious about spraying it “too wet”. My spray area is 75 degrees and air conditioned. I have 3 inexpensive oil / water separators between my 33 gal. single stage craftsman and my gun. My starting hose is the not so light weight style with a quick release at the compressor. That is running into a water separator / pressure regulator combo, then another $12.00 filter is in line attached to that pressure regulator. That is followed by 25 feet of 1/4 inch lightweight hose (9.00) on amazon. That is all screwed together with no quick releases. Then my gun has another water separator filter (about $8.00). The first filter seems to catch 95% of the water, as the filter after the pressure regulator stays almost dry. The filter at my gun has remained perfectly dry visually for what its worth. My compressor is in a separate office room because of the loud noise it makes. That room is also kept at 75 degrees as it is my personal office as well. I am not the fastest sprayer. In fact, this is all new to me. I have never sprayed HVLP from a compressor and wondered if my little 33 gal would keep up after reading that it would not, most every place I read. My pressure regulator is set at 29 lbs. My gun has a two stage trigger, but is not in an on air condition unless squeezed a little. I have only sprayed the tail surfaces so far. Granted, they are smaller, but my pressure gauge only drops 2 lbs the first instant I squeeze the trigger and then it stays constant at the original 29 lbs. From what I can tell, the quick release and filter at the gun, along with the 1/4 ” small diameter tubing, are not causing air restriction at the low setting. The only problem I have had is once spraying primer I crimped the hose accidentally and two paint drops came out the end of the nozzle, with one falling on my primed work. I simply let it dry and sanded it and a larger area around it and put on one more coat of primer. The result was no detectable visual of the primed drop which had also ran when I tried blowing compressed air to evaporate the water from it.

    I roughed my primer using both 320 grit wet/dry sand paper, keeping it dry, and red scotch bright. I found no difference between the two as far as top coat results. The 320 grit tends to take off some primer, whereas the scotch bright just makes it a bit duller than it already is. For making corrections, the 320 black that I’ve used seems to work very well without getting too deep to fast with limited pressure.

    Top coat: My calibration cup took 15.5 seconds (approx. based on 4 tests) to stream water to a break in the stream. So, I thinned the Tennesee red, after mixing with catalyst for 5 minutes, to 19 seconds. I was concerned it was too watery as the instructions call for 22-24 based on a Ford 4 cup that does water in about 17 seconds. My adjustment to “match” my water standard was off, as I put a tad too much water in. However, if the proof is in the pudding, my result is quite satisfying in terms of the shine and a wet looking finish.

    I only painted one side of my Wittman Buttercup rudder, which my standards is a relatively small rudder. This was a test, because, I thought if I would have a poor result, the rudder is the smallest thing to screw up. I believe I have 6 coats of paint on this. Remembering that I am a novice, my first coat, which should be a ghost coat, was probably a little light even at that. It was not an even coat; more inconsistent than any of you that paint would ever do if you were intoxicated. It dried to a tack in about 3 minutes with no color transfer on my pinky. I added a slight turn to give more paint and sprayed cross wise getting still far less than a saturated look. That coat took maybe 10 minutes or so to dry to a tack. By the fourth coat, each done crosswise to the previous, the color wan’t even, but was bright and no runs. For that I was happy. A testamony to the product is that I was able to obtain a homogenous look by doing 6 (maybe it was 6 1/2) coats. Only a couple times after a complete pass did I immediately go back a spray a line or two that looked a little thin. By the last coat, I had to wait about 14 minutes for the paint to not be a little “wet”. It wasn’t thick like lacquer, but I was concerned about the drying. I impatiently sprayed the final coat with my best consistency, distance (about 7″ inches I think”) and smoothness, while there was still a little transfer onto the only finger that was clean on my non spraying hand. I sprayed on a Saturday. turned the air to 80 degrees in my (near) Tampa facility and came back monday to find the paint had completely dried and with an attractively bright shine. My rudder is an 8 foot paint job…. meaning, it looks great form 8 feet away, maybe 5 feet if you are 60 or older and not wearing your glasses. There is a little (tiny compared to a house wall) orange peel which doesn’t satisfy me, but it was my first attempt and it will be a reminder that it was the first thing I ever painted. The fact that I painted it with a 1.5 nozzle is why I believe there is orange peel. Could it me the thinness of the paint I mixed? Maybe, be it didn’t run, and it dried well.

    It may be worthy to note, I sprayed with the rudder laying flat on the floor (cardboard), not hanging or in a fixture vertical. That would eliminate running, I expect. On the other hand, I don’t think I would have had runs with this. I’ve had plenty with latex and painting houses with an airless sprayer. Since Saturday, I ordered a gun with a 1.3 tip to do the rest of my topcoat. I like the Astro gun. So, that is why I went with another one.

    I hope others will share their experience. I am an old, newbie to topcoat finishes and am learning a lot and eager to learn more!

    Eric Klee

    Nick Bolandnkboland
    Post count: 1

    I suspect you will always have a bit of orange peel. If you ever get it to the point you are satisfied, I?d like to know how you did it. People who are not painters will think it looks great.

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