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Old 03-11-2005, 01:44 PM
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The clear test.

I thought this test may interest some of you.
The only painting I get to do anymore is my restorations and I have been doing them the same since 1985, apply three coats of clear and wet sanding the clear with 800-1200 and reclearing.
A lot of the rod builders use the same method. The painter from one of the big builders who for years has used the same procedure asked me a few weeks ago if there is a gloss difference between 800-1200?
I told him I just figured it would be best with the finer grit.
Here is what I did.

I took 5 - 1’x2’ panels epoxied and shot two coats of black base. I let them set for two days to make sure there were no solvents left in the base.
I shot 3 coats of a high solids clear with no flash time so none of the panels would have the benefit of a minute or two longer flash.
Next day I blocked a panel with 320 dry, one with 400 dry, 600 wet, 800 wet and 1200 wet.
Then shot two more coats of clear over each panel.

I let the panels set for 48 hours at room temp of 80 degrees and metal temp of 72 degrees.

The gloss meter I used is a cheap one with a cost of $5500 but has an accuracy rating of 95%. But across the board in this case there would be no variance for the readings were doing.

I would assume the 1200 would have the best gloss, right? Totally wrong!
The 320 won hands down and each panel loss gloss as the grits got finer.
There was a difference of 18% gloss between the 320 and the 1200.
I called a chemist friend at one major and he could not believe it and called another at another one and he said ,”oh we did that test 7 years ago” Just didn’t think the painters needed to know.

This is just backwards from what I thought it would be.
Oh, just bought a sleeve of 320 wet sanding papers.

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Old 03-11-2005, 01:51 PM
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Earlier in your article, you stated "320 dry" on the first panel. At the wrap, you were going with 320 "wet". Given what you now know, are you going to final sand wet or dry?

Thanks!

Russ
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Old 03-11-2005, 01:52 PM
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thats just great.

wth am i going to do with all this 800 i just "won" on ebay?
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Old 03-11-2005, 01:57 PM
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Quote:
Originally Posted by S10xGN
Earlier in your article, you stated "320 dry" on the first panel. At the wrap, you were going with 320 "wet". Given what you now know, are you going to final sand wet or dry?

Thanks!

Russ
With 320 wet for the only reason is the paper is less likely to load and make a deep cut or gouge.
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Old 03-11-2005, 02:05 PM
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You know what I think? I think the 320 was sanded first, then the others were sanded. The 320 sat for 10,20, minutes or longer even before it was cleared. That clear was allowed to flash off any solvents trapped a little more.

Plus of coarse the 320 would FLATTEN the clear prior to the next coats. The finer papers would "polish" them instead. Kinda like using the coarser paper to block plastic filler is going to CUT it down flat.
Maybe that is the biggest reason for the results come to think of it.

What do you think Barry?
Brian
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Old 03-11-2005, 02:14 PM
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Your right

[QUOTE=MARTINSR]You know what I think? I think the 320 was sanded first, then the others were sanded. The 320 sat for 10,20, minutes or longer even before it was cleared. That clear was allowed to flash off any solvents trapped a little more.
*********************************************
You are right, once you break the clear solvents rush out.
When I was done sanding the panels were lined up on a saw horse and cooked with a short wave for two 30 minute cycles. Took momma out to eat,
came back and cleared and went to bed.
bwk
************************************************** *

Plus of coarse the 320 would FLATTEN the clear prior to the next coats. The finer papers would "polish" them instead. Kinda like using the coarser paper to block plastic filler is going to CUT it down flat.
Maybe that is the biggest reason for the results come to think of it.
***************************************

This is exactly what happened! Its called "urethane peel" not always seen with naked eye but it is always there! The 320 leveled it. That means the test would be totally different for say lacquer.
bwk
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Old 03-11-2005, 06:24 PM
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Barry,Barry,Barry...

And I though it was a rookie mistake using 400 wet,'Cause it was quicker.....
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Old 03-11-2005, 06:52 PM
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Ok Barry, let me ask this, why put so much clear? Is it just for the depth? It doesn't get it any "flatter".

I have always simply applied three coats, cut it flat and buffed it. As I see it,you have a lot less chance for shrinkage, die back or whatever because there is less solvents in the film.

Now, the clear would make big difference. Five or six coats of a low quality, low solids clear would likely give you much more of the mentioned problems.

But just in general what have you found as far as a over all "Bestest" way to apply?
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Old 03-11-2005, 07:18 PM
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Bee 4me:
Thats what I like is how fast it cuts, man will this save a lot of time.

Martinsr:
Really it depends on the clear. With an acrylic urethane three coats is a good safe bet. Solid content also plays a roll, the higher the solids the less solvent that needs to escape.
Polyurethanes, the excess coats are not as much a problem.
Doing three a day (never more) polyurethanes seem to peak about (not-sanded between coats) 8 coats and more than that they get softer.

There is a big difference in gloss with mechanical measuring devices if you wet-sand and reapply.
But the other major factor is your sealing the first set of UV protectors from floating and on paper anyway you are doubling the life of the clear by letting the first coats dry and applying more. Real world, hard to say.
The other factor is UV's protect the clear by turning the uv's into heat so with the outside clear protecting the fist clear applied the heat stays on the top surface giving more protection to the fasting of the base.
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Old 03-11-2005, 07:43 PM
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Quote: Martinsr- You know what I think? I think the 320 was sanded first, then the others were sanded. The 320 sat for 10,20, minutes or longer even before it was cleared. That clear was allowed to flash off any solvents trapped a little more.

That's exactly what I was thinking as I read the test results. But I also think the fact that the 320 removed more material and also the deeper scratching with the 320 opened up more surface area for solvents to evaporate before applying the last applications of clear.

Barry, this is very interesting stuff. I've always used 600 or 800 wet before reclearing. My reason is because the 600 and 800 grit cuts the surface much flatter than say 1000-1500. I always use a thin rubber backer when I do the wetsand. I know exactly what is meant by urethane peel, sometimes I really do miss laquer when looking for total perfection. I don't think the 320 is going to give you the surface texture needed for a good clear application on a car- remember your test panels were shot wet on wet on wet with no flash time which might not be easily duplicated on a car- it may end up with quite a bit of texture if the clear can't be applied smooth on each coat? Very interesting testing-Barry it's apparent you are always trying to improve your results and methods- Thanks for sharing
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Old 03-12-2005, 05:23 AM
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That's exactly what I was thinking as I read the test results. But I also think the fact that the 320 removed more material and also the deeper scratching with the 320 opened up more surface area for solvents to evaporate before applying the last applications of clear.

************************************************

I tried to make this test as exact as possible. Thats why I used a short wave as a safety measure.
Also, for the clear I used a 55-58% solids (universal) not the highest solids
but by industry standards one of the highest.

With sanded top of clear the short wave should cure out the clear within 20-30 minutes. Not a 100 percent but all mid temp and tail solvents would be gone at that point and only curing left would be isocyanate curing.
I did two 30 minute cycles and than they set for about 3 hours before I got back to re-clear.

Another thing I did before I did a gloss reading is measure hardness of each panel, that will give you an idea how the clear is curing and if one panel is greener or not. @ 48 hours they were all at 95 % hardness.

Just a note for you that don't know what a short wave is.
They are a lamp and they have a long 1/4 inch (appox) diam bulb.
"infrared" is the correct name.
What they do is penetrate the paint to the metal and draw all solvents out.
They will work this way weather you have it close enough to get the metal temp to 100 or 140 degrees. (unlike heat)
A medium wave will penetrate about 1/2 way through the paint and do the same thing, just not as good as a short wave.

Ratings might be for a short wave as follows:
Body filler full cure @5 minutes
Lacquer primer @5 minutes
2K primer @10-15 minutes
Medium solids clear @10-15 minutes
High solids clear @ 15-20 minutes.

A medium wave you would double the above times.
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Old 03-13-2005, 07:24 AM
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This is very interesting, guys!

I don't know if Barry is in the mood for more experiments or not, but Martin's remark above about simply using three coats of clear, cut flat, and buff might be another interesting variable to add to the experiment. In other words, which gives the higher gloss readings, clear/sand/buff or clear/sand/clear?

Maybe Barry or Martin already knows the answer to this without even doing any more experiments...but I don't. Any guesses?

Also, Barry were your gloss readings obtained at 20 degree geormetry or 60 degree? How much of a spread in gloss readings from highest to lowest did you observe? I guess I'm trying to get a feel for whether we're talking hair-splitting differences or quite noticeable effects here.

Thanks for any comments.
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Old 03-13-2005, 07:50 AM
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[QUOTE=powderbill]This is very interesting, guys!

I don't know if Barry is in the mood for more experiments or not, but Martin's remark above about simply using three coats of clear, cut flat, and buff might be another interesting variable to add to the experiment. In other words, which gives the higher gloss readings, clear/sand/buff or clear/sand/clear?
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& &

This is most interesting and would require volumes to answer. But in short,
It depends! If the clear is a standard urethane made for everyday work such as a chey dealer wet-sanding and re-clearing can in some cases reduce gloss.
Clear is like diamonds from standpoint the resins used will decide clarity and if
a cheaper resin the clear will start getting cloudy after three coats. Varies by clear. Now with a good clarity wet-sanding and re-clearing can increase gloss level 30-40% net gain at 75 degrees.
BWK

Maybe Barry or Martin already knows the answer to this without even doing any more experiments...but I don't. Any guesses?

Also, Barry were your gloss readings obtained at 20 degree geormetry or 60 degree? How much of a spread in gloss readings from highest to lowest did you observe? I guess I'm trying to get a feel for whether we're talking hair-splitting differences or quite noticeable effects here.
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& &&&&&&

The gloss reading was 18% from best to worst, don't sound like much but all these little percentage increases add up but as competitive the shows are now.
I use a 35 degree angle with metal temp at 74 degrees.
Reason was in this end of business flatness is usually rated at 70-75 degrees at 30-35% angle, Not sure why but the military uses this spec a lot so I guess thats how the 35 degree came into play. Not sure if one more degree in metal temp would have made a difference so I did not worry about it.
BWK
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Old 03-13-2005, 01:28 PM
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Quote of Barry's "a cheaper resin the clear will start getting cloudy after three coats."

Boy if that isn't the truth. I forget the darn number but when I was repping M-S we had a clear that with a few too many heavy coats it would turn the most God awful milky white color.

I really like it's performance, two wet coats and it it just WOULD'T run, it was very user friendly. But this caused a problem because where some other clear would have been dripping on the floor, this one hung on the panel like glue. People would bomb on two coats, and if that was good three or four would be better right?


Over something like a black, the darn thing would look like a "Gray Ghost" candy.
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Old 03-13-2005, 03:09 PM
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Quote:
Originally Posted by MARTINSR
Quote of Barry's "a cheaper resin the clear will start getting cloudy after three coats."

Boy if that isn't the truth. I forget the darn number but when I was repping M-S we had a clear that with a few too many heavy coats it would turn the most God awful milky white color.

I really like it's performance, two wet coats and it it just WOULD'T run, it was very user friendly. But this caused a problem because where some other clear would have been dripping on the floor, this one hung on the panel like glue. People would bomb on two coats, and if that was good three or four would be better right?


Over something like a black, the darn thing would look like a "Gray Ghost" candy.
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& &

People don't realize that if you make a clear for a dealership you make it to perform to solve their needs, maybe 8 spot jobs a day.
The clears made for this type work do what they are intended for very well.

Now you go back to House of color when John owned it his two clears were made for clear/sand and clear.(top notch clears!)
Of course today, those clears are nothing like they were when he owned the company.

You can make clears to perform in one area but you take away from another or at old math "for every positive there is a negative"
Nitch marketing at its best!
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