Urethane Wave

sprint_9

sprint_9

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Wanted to take the time to post a few questions, I kind of know the answers on some of this, but want to discuss anyway.

On my C10 I cleared with Universal, and I have what I assume is urethane wave, its really noticeable when looking almost straight down the side of the truck. If you back off and change your angle just a little bit to more of a side view it becomes much less apparent.

Ive done some reading on my past notes and found with my doors I started wet sanding with 800 and worked up. With my box I didn't get as aggressive and it definitely shows much more wave than my doors, although my doors do still have slight amount.

So not being aggressive enough sanding has led to some of the issue that I see and that part is a relatively easy to fix on the next project.

The real question Id like to answer is how to avoid getting it in the first place. I've ran through a few different scenarios and obviously my spray technique could be better. I think what is happening is I end up putting wave into the clear by flooding it to not have dry spray. Most of my setup and gun factors were fairly good I think, but I typically was around 50 percent overlap, and I read that it might be better to be around 75 percent overlap. That equates to a pretty large change when comparing back and forth. So something like a 75 percent overlap is something Id like to work towards as I think it will help in my situation. I just don't think I will pick that up right away with how little I've sprayed and how little work I do.

I'm wondering if there is something else I can try until I get to that point? I like Universal and its properties, but I'm wondering if I should try Euro? I see a lot of really nice jobs with it and see that people really like it and speak highly of it. One other idea I had was trying a little reducer in Universal to see if that would help, my first thought is it would, but at the expense of reducing the solids. I think to some of the issues I had with 2k primer and what adding just a little reducer to it did and wonder if the same type of gain could be had with Universal.
 
ok, here is my take. When I use universal I automatically know Ill have to start stick sanding with 600...800 at the minumum. I normally go 4+ coats on my clear and that stuff is thick..

I recently switched to euro and shoot it 4:1:2 and my world changed..

Some people can lay out UV like glass, i just cant anymore. but Euro is my absolute go to now.

For me to get UV to lay out really nice I have to crank my pressure up to 40+ on my prolite. I'm just not interested in that anymore. I've learned that maybe I'm more of a "Medium Solids" kinda guy!
 
Being that it is a true high solids product it is inherently more difficult to spray than other clears. I also find it harder to spray and achieve a slick finish with no texture. Following Barry's advice on air pressure is key with Universal. I was a doubter until I tried it finally and it made a difference. I can still spray Euro far slicker than UV, but that is to be expected as less solids in Euro and it is more forgiving, which is why it is an excellent clear for collision. Like Dave said above, more overlap, faster passes (relative to less overlap) combined with more pressure are the things you want to do when spraying UV.
I have resigned myself to the urethane wave though especially if you are putting more than 3 coats on. After three it happens, been my experience that all clears will wave like that once you get more than 3 coats on. Some worse than others. I just accept it cause if I put more than 3 coats on I'm planning to buff anyways. Like OJ said a good stiff block and coarser grit is what you need to get rid of it. As coarse as you think you can get away with. Next big job I'm thinking 400 wet on homemade acrylic blocks.
 
Agree with everything above. I, too, find once I get over 3 coats it is there no matter what I try. What has helped me some is turning in the material 1/2 turn more than "normal" settings, upping the pressure, and faster passes with more overlap, as mentioned. Retarder can help quite a bit, and if you use enough, makes it spray more like Euro with a little flow. The last complete I did with 3 coats of Euro mixed 4:1:1 came out exceptionally flat. I haven't been able to get Universal as slick as this one came out. Universal usually gets 3 coats, blocked with 320-400, then 2-3 more. Two coats comes out nice and flat, 3 and slight wave will usually start showing for me.
 
Euro - 4 coats- soft block (meguires) 1000 grit BUT like I said- fast, a lot of overlap ( actually I think I go over the same spot twice) fast and almost dry- just barely wet. Works for me but still learning - that’s with an lph400 - 2 and 3/4 out volume- air at about 35lbs
 

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Plexiglass blocks that are thin enough to flex and conform to the surface shape will help a ton in getting the wave back out, along with aggressive enough paper, 5-600. Use a dry guide coat after the initial blocking so you can make sure you're getting all of the scratches out.
 
5% retarder in the Universal has really helped me. Summer or winter it makes it lay down better. Still has urethane wave but doesn't seem as bad.

10% might be better but I haven't had any jobs lately where I wanted to experiment and get into a run situation.

I block with 800 grit on a long durablock and it does a good job. I used to use 1000 on the durablock but the 800 looks a little better. I haven't tried 600 yet.
 
Gmills said:
How long of a block are you guys using to cut the wave? What grit can you swap to a rubber pad or something softer? I have a hood with four coats of UV I need to sand in the next week or so and I don't want to mess up.
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11" long block using 9x11 wet paper. Like OJ said, once you get to 1000 you are just removing previous grit scratches so you can use a smaller softer block. When I'm blocking out the wave I'll go 45 degrees longitudinally (lengthwise-front to back) to the panel. Sometimes I crosshatch. Once I think I have the wave out, then sand just back and forth keeping my scratches all going one direction (usually longitudinally).
 
I use 16" and 11" durablocks. seem to always reach for the 16" on longer panels. The longer ones didn't seem to be an improvement and are harder to operate.

I have 3 of each and have to constantly rotate because the psa won't stick to a wet block. Change blocks with each paper change and rotate.

I also change to a soft block at 1000 grit and up. I use 3m sleeves on 1000 and up and klingspore rolls on 800 and under.
 
serjik911 said:
For me the easiest to spray was universal clear.
Production was fine and Euro was the hardest to spray
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I 100% agree with you. Noticed with the euro even at 4:1:1 with Sata rp 1.3 30psi, 1.5 turns out very fast gun speed still getting urethane wave.
 
Do any folks out there have tips on spraying Production clear to get the least amount of, as sprayed, orange peel?
 
There will always be orange peel. It depends how much or rough a texture it leaves. Even new models have it, some worse than others , and they have the best spraying facilities around. You just have to learn how not to have too much. And that takes time and experience.
 
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