Flow coating. What's your method?

B

bomccorkle

As a preface I have been flow coating all of my personal projects and the ocassional customer project for a while now. Maybe the way I do it is just how it is but just wondering if anyone else out there has any pointers, tricks, time savers on doing it.

My method is to spray base then wait overnight, the next day I go out tack off, then spray 3-4 coats of uv clear.

The next day I go out and block the car in 400 dry, re apply w&g remover, tack off, then spray another 3-4 coats of uv clear with a splash of retarder or one grade too slow activator; from there i let it sit until assembly then begin the cut and buff around 1000 g on up.

Anyways I guess my biggest question is in the blocking before coats if anyone has found anyway to save a little time/effort. I hand block it all and 400 dry loads up quick, I tried wet but then I am just constantly wiping panels trying to see what I have. Maybe it's possible to step down to 320 g but that may be pushing it on scratch shrinkage, I'm not sure.

Anyways, maybe this thread can be of some use to us all, and surely we can get some newbies doing it.

It's still worth the extra work for all of that depth and clarity.
 
You're a brave man, I've never had the courage to go coarser than 600 wet. Ive done this a lot with PPG DCC. 3 coats let it sit a few days then 600 wet and 3 more coats. Then 800-1200-2000-3000Trizact 5000Trizact and buff. Makes me tired thinking about it.:)
 
Yes no doubt. 400 works great actually. I used to do it at 800 wet.... an eternity. 400 does work out well. Like I said paper goes a lot further wet but it's a pain to see how flat things are.....
 
I just hose the clear on to start with and if flows plenty - sometimes even making it to the floor. LOL

Seriously though, I use a similar method as your only I do the initial wet sanding with a piece of oak and 800 grit. Yes, it does take forever but I work about an 8" square section at a time and keep a spray bottle of water and squeegee close at hand.
 
Here is something interesting, I plan to try.
I have heard from a number of shops (7-10), now and all swear you have never seen anything like it.

They do 3 or 4 normal coats waiting 30 minutes between coats, then as soon as done with 3rd- 4th coat they mix more clear and I have been told from some they add 30% retarder and some they add 50% and right away put a 5th coat on.
Makes sense to me but have not tried it myself yet.

This is why I love the tech line, learn something everyday!
 
Is that 30-50% retarder by volume?? I only use about 1-2 Oz per quart. But I would suppose that would make for an awful slick surface.
 
Barry;n74146 said:
Here is something interesting, I plan to try.
I have heard from a number of shops (7-10), now and all swear you have never seen anything like it.

They do 3 or 4 normal coats waiting 30 minutes between coats, then as soon as done with 4th coat they mix more clear and I have been told from some they add 30% retarder and some they add 50% and right away put a 5th coat on.
Makes sense to me but have not tried it myself yet.

This is why I love the tech line, learn something everyday!
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Hmmm, I would think it would dull the surface with that much solvent. Maybe since they are spraying it on the fresh clear it melts into the lower layers and lays flat and shiny?
 
Yes by volume and yes the statements have been, looks like it is dipped.
 
An additive barry sells to slow down your catalyst reaction. So if it's balls hot and you have slow you can turn it into very slow, or by the heavy mixing ungodly slow. It also works in your 2k. Here in ks when it gets about 90 degrees 90 percent humidity the 2k will damn near dry spray from the gun. Mix in a bit of retarder and good as gold.

Barry also makes an accelerator for spraying when it's cold or I mainly use it when I am 2k'ing a large area eg. Shells, bodys. I mix enough for one coat and accelerate, then repeat for the 2-3 coats, when you are done rinsing the gun it's time to block, fantastic time saver in that area and also good for stopping clear sags in the dead of winter.
 
Barry;n74151 said:
Yes by volume and yes the statements have been, looks like it is dipped.
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Are they still spraying this as a heavy wet coat typical of uv clear or maybe just medium wet? I'd be afraid of being in run city spraying that way.

Also barry would maybe waiting more than a day before blocking prior to flow coating maybe stop some paper clogging or is the clear reaction pretty much over with? I know it is still off gassing for quite a while but had always assumed at around the 24 hour mark the majority of the reaction was complete?
 
i always do 3-4 coats, block with 320-400 then reclear. depending on what it is after i block i will buzz a day over it with 600 just to smooth out my blocking scratches then goto town. i always sand with 320-400 though since the whole purpose of flowcoating is to get rid of or reduce the urethane wave. blocking with 600-1000 just doesnt cut that out.
 
So clear will cover 400 wet scratches? And when you are sanding the clear are you guys straightlining it or do you sand at a certain angle? Kinda like half a crosshatch (45 degrees)if that makes any sense. I always seem to be able to still see the scratches with when I sand 45 but if I straightline it back and forth doesn't seem to show up nearly as much. What's working well for ya'll?
 
Chris_Hamilton;n74166 said:
So clear will cover 400 wet scratches? And when you are sanding the clear are you guys straightlining it or do you sand at a certain angle? Kinda like half a crosshatch (45 degrees)if that makes any sense. I always seem to be able to still see the scratches with when I sand 45 but if I straightline it back and forth doesn't seem to show up nearly as much. What's working well for ya'll?
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Yes, it will. This winter the garage was colder than I thought with the fans on and I got some serious runs on a couple not so important parts. I sandded the runs out with 220 and cleared right over it. Not that I am recommending this, but it worked. The biggest thing with sanding with coarse dry paper is gouging when you sand up to a bead or other body line. You really have to watch your technique in those areas or it will show.
 
bomccorkle;n74157 said:
Are they still spraying this as a heavy wet coat typical of uv clear or maybe just medium wet? I'd be afraid of being in run city spraying that way.
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Im also curious about that….and I looked quickly in the tech manual and didn't see the retarder??? Could this be used on a typical 2/3 coat job for a little more flow?
 
bmenard;n74173 said:
I looked quickly in the tech manual and didn't see the retarder???
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It's on the Pricing page under Urethane Reducers: Item #925-4 Polyurethane Retarder Quart New $27.40
 
[QUOTE='68 Coronet R/T;n74179]Get ready Barry, a run on Retarder is in the wind.[/QUOTE]

No doubt. Once you use it for your clear or your final clear flowcoating you wonder why you hadn't always kept a quart or two on hand.

I have ran a 400 interface pad over clear to reclear a screw up but it's good to know that 320 will still clear out when blocking.
 
When doing 3-4 coats I can usually still finger print the next day. 2 coats never a problem.

After you guys are done with the second round of clear are you starting out with 400 for you cut and buff? I usually do the 4 coats followed by 800 up wet and I never go through the clear. I'm blocking with 12" durablocks and rolls of 800/1000 grit paper before I switch to the sheets of finer paper and a soft block. I'm a little uncomfortable getting 8 coats of clear on sharp body lines or panel edges.

Now if I get an occasional run or sag and have to 400 the panel and start over then I suppose I flow coat but my cut and buff is the same procedure so it doesn't look any different than 4 coats and a cut and buff.
 
I start my cut and buff at 1000 after flow coat. At 800 for any waves, runs, sags, etc that pop out with the 1000.

I typically block at 1000, then move to finishing film and an interface pad for 1000, 1500, 2000, 2500 wet bufflex, 5k trizact, and then starting at v34, v36, v38 Chem guys compounds.
 
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