Forgot how to spray UC, switch to Euro or Production?

MDPotter

MDPotter

Promoted Users
I've painted the cab, doors, and fenders on this truck and all has gone pretty well in terms of how the clear laid down. But the last few panels I did (hood, bedsides, tailgate) all came out with significant runs/sags. Same gun and settings, same air system, but temperatures were lower. I'm using a Tekna Copper with the 7E7 cap, 120+ at the wall, 26-28 at the gun trigger pulled, 2.5 turns out on fluid, and nearly all the way out on fan. I was moving 50-75% faster than usual as well and I still got these huge runs/sags. I had the bedsides laying flat and the tailgate hanging. I have trouble making the concave section of the tailgate come out nice due to that contour.

First question - how do I fix this? Is it worth using a razor blade to scrape the highs off and then 800, 1500, 3000, 5000, then polishing steps? Or should I just sand it down and respray? I can take the tailgate off without too much trouble, but the bedsides are installed and they're a lot of work to take back off.

Second question - is Euro or Production clear less likely to run or sag as they are not high solids? I'm thinking I would rather use those clears as I don't do any cutting and buffing as I've been happy with the results straight off the gun up until now. It would also be nice for the clear to more scratch resistant sooner.

Bedrails:
IMG_0178.jpg



Tailgate:
IMG_0179.jpg
IMG_0180.jpg
 
I had a door that looked like that bed rail. My best piece of advice to offer is to let it sit at least a week before sanding it completely flat, you can sand it open and knock it down a little. Just don't sand it flat too fast or it can ghost back on you and you will have to re clear for sure then. Id probably re clear the tailgate personally, those areas suck to get aggressive sanding and then trying to buff.

When spraying my tailgate what worked decent for me was spraying the angled part of the recess. Try to put the center of your fan roughly centered on that angle, one pass on the top and one on the bottom angle, tilting your gun to match the angle. When doing so make sure the edge of the fan is roughly lined up with the crease of the opposing edge where the angled part of the recess meets the flat part of the recess. If it looks a little dry you can make a quick pass trying to get into the center of the recess, but that can backfire quickly.

Temp and humidity always played games with me. Shooting in August and not shooting again for a month or two is rough. I think humidity plays as big of a role as temp.
 
I agree with Shine, it's not the clear its the guy behind the gun. ;)
Seriously, you can get runs in any of the SPI clears (ask me how I know. LOL) when the gun isn't adjusted properly or your technique is a bit off.
I stumbled on my air hose recently and moved the gun too close to the the panel for just a second, and when I came back for the second coat there was this run laughing at me.
 
Thanks for the advice guys. I didn't mean for it to sound like I was criticizing the clear. It's definitely user error, I was just wondering if I would have better luck spraying a non-high solids clear. I've been putting off dealing with these just out of excitement for getting the truck put together and running and also out of disappointment with the results. I'll have no choice but to work on this soon.
 
MDPotter said:
Thanks for the advice guys. I didn't mean for it to sound like I was criticizing the clear. It's definitely user error, I was just wondering if I would have better luck spraying a non-high solids clear. I've been putting off dealing with these just out of excitement for getting the truck put together and running and also out of disappointment with the results. I'll have no choice but to work on this soon.
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It can definitely be an emotional roller coaster!
I'm no pro by any means, so take my input with that in mind.
I was getting runs in the clear as well. I noticed that they were happening in the overlap sprays.
I was trying to get it to be wet and glossy on the first pass.
I switched, put less down on the first pass and then started looking closely at the way the clear was laying down and flowing in the overlap area.
That helped me a lot.
 
Don't get anywhere near shooting a "tack coat" with Universal Clear (my only SPI experience). It seems to want a fairly full first coat, or it will show undesirable texture. As Shine says, crank up the pressure a scoche and crank down the wetness. Shoot some cardboard to perfect, then shoot your job. I hope others will elaborate with respect to other SPI products. Good luck!
 
Shine said it perfectly. Only thing I can think to add is that along with upping the pressure and cutting back fluid is to make sure your overlap is around 75%. Identical robotic passes. Spray in straight lines. Keep the gun head parallel to the surface.
 
So I took the tailgate off the truck, sanded it down, and resprayed it with higher pressure (about 31 psi) and dialed back fluid (turned 1/2 turn inward) and still got runs as bad or worse than before. Medium activator. The surface temp was 63*, is that too cold and would it cause runs like this?

IMG_0264.jpg
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Okay, here's my take.

Try to get the metal temperature to 70 degrees. Also, in colder temperatures the flash time between coats needs to be increased quite a bit. I generally wait until I cannot see solvents flashing off and I can touch the clear in an inconspicuous area and not have it stick to my glove and pull away any strings.

Personally, I am a 50% overlap guy, since it makes it easier to be consistent in my application. I just point the nozzle at the previous wet edge.

These tailgates are tricky because of all the angles. It is easy to apply a really heavy coat where you are overlapping in several directions.
 
Another thing I do is to set my gun up using masking paper taped to the wall. Hold the gun the correct distance from the paper and pull the trigger full open for 1 full second. You should have a full wet pattern but NO runs.

This will get you started and if necessary you may need to make adjustments depending on your spraying speed.
 
'68 Coronet R/T said:
Okay, here's my take.

Try to get the metal temperature to 70 degrees. Also, in colder temperatures the flash time between coats needs to be increased quite a bit. I generally wait until I cannot see solvents flashing off and I can touch the clear in an inconspicuous area and not have it stick to my glove and pull away any strings.

Personally, I am a 50% overlap guy, since it makes it easier to be consistent in my application. I just point the nozzle at the previous wet edge.

These tailgates are tricky because of all the angles. It is easy to apply a really heavy coat where you are overlapping in several directions.
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I will get the temp higher on the panel next time. Sadly this was after the first coat. I usually do 50% overlap as well.

What I should really do is sand down a scrap hood I got from a local body shop and so some testing on it before I waste more material and time on this tailgate. It's just been a mystery and frustration because the only thing that has changed is going from 70+ surface temp to 60's.

Could it be expired clear or activator? The clear and activators are a year or less old (opened and resealed a couple times).
 
MDPotter said:
Could it be expired clear or activator? The clear and activators are a year or less old (opened and resealed a couple times).
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Activator does expire after opening and that could be the issue, or at least part of it.
While Barry and I were talking we got on this topic and he said it the exposure to air that affects the life of the activator.
Should always minimize the time the can is open, and the less material in the can, the more air and bigger impact.
A trick he told me was to stick the tip of a MIG welder in the can and give it a quick shot.
Argon is heavier than air and will form a "blanket" and will isolate the activator from the air in the can and keep it lasting longer.
 
MDPotter said:
I will get the temp higher on the panel next time. Sadly this was after the first coat. I usually do 50% overlap as well.

What I should really do is sand down a scrap hood I got from a local body shop and so some testing on it before I waste more material and time on this tailgate. It's just been a mystery and frustration because the only thing that has changed is going from 70+ surface temp to 60's.

Could it be expired clear or activator? The clear and activators are a year or less old (opened and resealed a couple times).
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I highly doubt it is from the clear or activator. I have sprayed UV and Activator that had sat in my cabinet for 7 years. http://www.spiuserforum.com/index.php?threads/uv-and-activator-7-years-old.6416/

What tip do you have on your Tekna? I have a Tekna Copper 7E7 and find it shoots clear better with a 1.3 tip. Again setting it up on paper saves a lot of aggravation.
 
'68 Coronet R/T said:
I highly doubt it is from the clear or activator. I have sprayed UV and Activator that had sat in my cabinet for 7 years. http://www.spiuserforum.com/index.php?threads/uv-and-activator-7-years-old.6416/

What tip do you have on your Tekna? I have a Tekna Copper 7E7 and find it shoots clear better with a 1.3 tip. Again setting it up on paper saves a lot of aggravation.
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I have the 7E7 cap and 1.3 needle as well. I was thinking about trying with my Devilbiss FLG2 just for fun if I have the right size needle. I wish I could take a week off work and just experiment and perfect my painting techniques. Maybe not perfect but at least get to where I'm happy with the results. I sprayed my 68 and didn't touch a single inch of it with sandpaper or a buffer. It was blue which helps but I only had a couple runs on it and the finish was great.
 
Technique needs adjustment constantly depending on several factors, temperature being one of the biggest. The viscosity changes with cool weather. Thicker clear causes you to slow down to get the wetness you are looking for, then the temperature causes it to move (run) before it flashes. Ten degrees colder may not seem like much, but you are getting at the bottom range that the material is designed for. The answer is not putting it on so wet. Speed up your passes, turn the fluid in more, back up from the surface, and raise pressure. Heating up the panel and material would help a lot. Heating up the clear and catalyst to 90+ before mixing will thin the clear out, making it wet easier and flash quicker. Hope this helps.
 
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