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The too often call.

Barry

Paint Fanatic
Staff member
#1
Over the last year I have gotten way too many calls like this.
I laid 4 or so coats of clear and then wet sanded and buffed and now I have urethane wave.

Simple answer, you do not block fresh clear like you do a urethane primer be it 30-45 deg angle.
Think about this if doing a hood or large panel, one or two extra strokes stopping in center of panel will make the clear uneven.
Always block clear in a straight long stroke motion.
This is mostly for the do-it-yourself people but if doing insurance work with just two coats of clear, really would not make a difference.
 

Barry

Paint Fanatic
Staff member
#4
Wouldn't it be better to do two coats then sand, then do the last two as a flow coat?
No as most do 3 or 4 than sand.
Two coats and sand to me would defeat the purpose because of mils.

In an insurance shop if high solids is used for a repair they would never do more than two coats, even if a new mercedes so you will never get urethane wave with two coats or 4 coats with a medium or low solids panel repair clear.
Solids is what makes the high end restorations or restro rods we do and solids is our best friend for depth, gloss and protecting the basecoat.
 
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Barry

Paint Fanatic
Staff member
#6
Wave is caused by one thing SOLIDS.
If we use a low medium solids clear, won't happen, so with top notch work solids are your best friend.
 
#8
Something Im not sure on is how you do rounded portions, or what type of block/pad do you use on the curved stuff or just in general? Ive seen some guys talk about using a piece of oak in some old posts Ive read, but Im not sure if something else can be used thats easier to navigate curves with.
 

elwood

Registered Users
#9
This is a good thread. People who only do a car or two don't really have the hours and hours into this kind of work that enables them to learn from any mistakes. At one time we all had our first car that we had painted. Of course we wanted it to look good but didn't know the "tricks of the trade". Mistakes made, experts taught us what went wrong and we tried to do better. Thanks to all who contribute here we all can learn alot of different things.
 

Barry

Paint Fanatic
Staff member
#11
Something Im not sure on is how you do rounded portions, or what type of block/pad do you use on the curved stuff or just in general? Ive seen some guys talk about using a piece of oak in some old posts Ive read, but Im not sure if something else can be used thats easier to navigate curves with.
Everyone does this different and there are no right or wrong answers, personally I never use a hard block on fresh clear, I always use a hand pad and the curved area the palm of my hand BUT this goes back to the 70's when we were taught this way and also told you keep hand flat so you don't finger f the job. ( no other way to put this as it was beat in our head) LOL
Then again like the old day body filler I finish in 80 and glaze I Finnish in 180, so would be thrown out of any tech school class.
 
#12
I confess to using the oak hard block with 1000 grit method for cars I want to really pop when done.
Obviously this doesn't work well on curved areas so I use a round Durablock for those areas.
IMHO, once the clear is free of orange peel, it should also be clear of urethane wave using this method. After that I use a soft block with 1500 and follow with 2000.
 

Attachments

#13
The areas that get me are the concave curves, they tend to magnify the urethane wave as well as being more difficult to block properly through the whole process. I never used to get this with the old Deltron clear back in the 90's, so I wonder sometimes if it wouldn't be better for final appearance to mix SPI clear as an MS clear but use more coats. Obviously you're dealing with more solvent and more time needed to get it all out, in a way you are going backwards, but in theory it might work if done right.
 
#15
I'd back up. Easy to think it's urethane wave & not what's under it.
Water is thick and hides some imperfections before base.
I'd start with asking was area guide coated, then how many completes with success.
Body work is an art & some have it, some take longer then others but eventually if you really want it, you'll get it.
Novices like myself lay many extra coats of clear to finess what i can't feel in prior steps & spray technique.
I hard block clear gently with 600 even 400 for disaster runs & hard block till 1500 sometimes.
Switch to padded after that to lessen dirt scratches.
I stay further away when spraying at the cost of waste in hard areas.

68- beautiful, guessing you've got more then 6months experience heh. Tell em.
 
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#16
in most cases the urethane wave is already there mostly from spray technique. the person just doesnt see it with the orange peel there until they sand and buff to make it really glassy. now all of a sudden its much more noticeable.
This is spot on to what happened to me. I was one of the calls to Barry on this, just this last weekend to be specific. I had what looked like a decent panel, thought I just needed to make it slick and did so, only to have it end up lumpy once it was buffed. I then cut it back down but didnt go aggressive enough since I was worried about getting too thin on the clear with all the sanding and buffing I had already done. I wasnt satisfied with it so I blocked down and re cleared.
 
#17
'68, what was the clear process on those pics you posted?
2 coats with no reducer.
Final coat with 10% retarder added.
Using a Tekna Copper E7E 1.4 tip at 30 psi.

The trick is to be consistent on your distance from the panel and make sure the first coat goes on wet. My technique may not be the way the pros do it so encourage you to follow their suggestions. I find I am always spraying clear at the very point were runs like to show up. LOL
Euro Clear is my current favorite.
 

Barry

Paint Fanatic
Staff member
#19
I was in a shop about 6 months ago or longer and the guy was building a 66 chevelle for his dad and had put 6 coats of universal on the hood, rest of car was done months before, the hood was slick and looked like it had been dipped and NO urethane wave.
Two months later stopped in and his dad was pissed so he wetsand and buffed himself, I think he wanted to kill me because the urethane wave was awful.
I asked how he sanded and sure enough he blocked it on an angle like primer and buffed.
I said take a soft pad with 1000 and sand in a long straight line until totally dull, than convert with 1500 the same way and buff.
The hood turned out perfect.
 
#20
I confess to using the oak hard block with 1000 grit method for cars I want to really pop when done.
Obviously this doesn't work well on curved areas so I use a round Durablock for those areas.
IMHO, once the clear is free of orange peel, it should also be clear of urethane wave using this method. After that I use a soft block with 1500 and follow with 2000.
If you listen to these guys from day one you can get great results, I followed what Barry, '69, Jim, Shine and others said and this is my first real paint job ever. It came out beyond my wildest expectations. I will be starting on paint for a B1 Blue Duster for my daughter in a few months so we will see if this was just a fluke or what these guys say is repeatable :). This is 5 coats of UC put on heavy enough to get a few runs then using the hard block technique with 1000 grit like '68 said then 1500 and 3000 with the palm of my hand like Barry said.

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