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Old 01-27-2009, 07:42 AM
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Just how much does clear "fill", a little test I did.

You know me, always doing some goofy test or something. The subject of flow coats and how many coats of clear often comes up. A while ago someone asked if their clear would fill some imperfection. I forget what the exact thread was about but it got me to thinking, clear has as much or nearly as much "solids" as urethane primer, so I'll do a little test to show how much it can actually "fill".

I took this piece of metal and made a few dents. I then filled those areas with filler and sanded one half of each spot with 120, the other half of each spot with 80 grit paper. I then cleared one half of the panel with two coats and one half with four coats.

So what I have is four coats of clear over 120 and 80 grit sand paper scratches and then two coats over the same. I mil checked everything prior to clearing to see what I had and then checked it later after clear, the two coat side gave me 3 mils and the four coat side gave me 6 mils. Now, we have to give a little one way or the other a half mil maybe more being this is a cheapy mil guage but these are the numbers one would expect.

The filler was seriously buried under that four coats I'll tell you that! It looked like a sheet of glass over the top of it, burying those scratches big time. On the two coat side you could see a little dryness, I can't say could could see the scratches because that 3 mils filled them, but there was a little that you could kinda see.

I took 1500 wet to it and cut it aggressively. No checking to see when I just cut it flat, I sanded the hell out of it and cleaned it up to see all the scratches gone completely. I polished it to a shine and mil checked it to find I had cut a about a mil off, maybe a little more.

So here it I have 80 grit scratches totally buried under clear with 2 or so mils (the absolute minimum you would want) on the two coat side and a full four mils on the four coat side!

This clear acted just as primer in filling these deep scratches. Hell, we don't even ask the primer to do that around the shop. NO filler would EVER be primed over with anything more coarser 180 scratches.

The point of this is, clear adds a lot of film build. A few coats is plenty to cut and buff and adding a bunch is SERIOUSLY adding to film build.

This is not to say that a "flow coat" is bad, but just be aware you are adding quite a bit of film thickness with every coat of clear, that is all I am saying.

Makes you go hmmmmmmm, don't it?

Brian


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Old 01-27-2009, 08:19 AM
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So AFTER you cut and polished you ended up with 2 mils on the the 2 coat and 4 mils on the the 4 coats?
I am sanding and buffing (with 4 coats of clear) and was concerned I might get below the 2 mil minimum while getting out orange peel.
Forgive the newbie question but what is the downside of having 4 mils of CC?
Another good write up!
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Old 01-27-2009, 11:38 AM
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If you are really in a testing mood, how about adding this one to this particular study. Shoot a panel in Black urethane. One side sand with anything under 180 grit. On the other side, don't sand at all or color sand as you would normally do to polish the urethane.

Now shoot your 3-4 coats of clear over both and color sand both. My question would be, do the scratches on the coarse side of the panel show up in the clear - even though the surface is glass smooth. I'm thinking the clear will act something like a "lens" and actually magnify or show those sanding scratches down in the base paint quite clearly. (You may already know the answer to my question and don't even need to run the experiment.)
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Old 01-27-2009, 04:06 PM
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I'm also wondering if the scratches can bee seen. Also did the clear actually stick to the sharpie ink?
Shane
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Old 01-27-2009, 08:06 PM
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I'll see about doing your test Dewey.

Restorod, there isn't a big deal about the 4 mils of clear. My whole point was to simply make a visual example of just how much film build you get with multiple coats of clear.


Shane, you do see the scratches. It is kinda cool running your fingers over this thing. Kinda like the tables with coins and crap buried under resin.

On the Sharpie, I didn't do any test to see how well it "sticks". I assume it sticks just fine because the solvents go right thru it. The interesting thing about the Sharpie is that if I were to paint a SS paint over it, that sharpie will bleed thru the paint BIG TIME. I am talking it looks like someone wrote with the sharpie AFTER it was painted! It REALLY will bleed thru paint like nothing I have ever seen. Only made that mistake once!

Brian
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Old 01-27-2009, 08:31 PM
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good test, so you are saying i don't have to sand and block now just shoot a bunch of clear over it. lol just messing with you it interesting to see how fast and thick it adds up.
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Old 01-28-2009, 05:19 AM
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Clear is more expensive

I read your post but wanted to make some clarifications. The test you performed is very dependent on the type of clear you used. The solids content of the clear is the key. The higher the solids content the better the product will fill and the less you will have to use to achieve filmbuild.
The difference in price of all paints is a direct result of solids content. There are three componenets tp paint, Solvent, Resin and Pigment. The solvent is there to mainly help transfer the product with a paint gun, resins allow flow and pigments allow fill, color uv protection etc.... Primer is more cost effective to fill defects, scratches and allow a good barrier for corrosion protection.

This is the biggest differance in many generic qualities versus a paint like DuPont's. Many painters, shop owners seem to think a cheap generic gallon of paint is more cost effective than a name brand. Not true, it will take more coats of a generic to achieve the same film build thus your costs increase as well, not only that, more solvent is being released into the air with generics.

FYI to all. When you approach 12-14 mils of paint film, it's time to strip your part or cracking will occur.
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Old 01-28-2009, 06:51 AM
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Quote:
Originally Posted by cifanif
I read your post but wanted to make some clarifications. The test you performed is very dependent on the type of clear you used. The solids content of the clear is the key. The higher the solids content the better the product will fill and the less you will have to use to achieve filmbuild.
-------------------------------------------------------------

I think you missed the purpose of the test, filling at 1.5 mils per coat would indicate he is using a medium solids clear and it is still filling the scratches.
This is a valuable test from the standpoint you will see a lot of questions on here for re-clearing wondering if they need to use 1500 etc so scratches do not show. Of course Higher solids will fill more but medium solids is the most popular clear used over all.
BK
========================================

The difference in price of all paints is a direct result of solids content. There are three componenets tp paint, Solvent, Resin and Pigment. The solvent is there to mainly help transfer the product with a paint gun, resins allow flow and pigments allow fill, color uv protection etc..
--------------------------------------------------------------

Resins do not allow flow, mid temp and tail solvents do that.
Pigments fill nothing and have no strength and are for hiding or color uniformity.
BK
================================================


.. Primer is more cost effective to fill defects, scratches and allow a good barrier for corrosion protection.
-----------------------------------------------------------------

He was not suggesting using clear instead of primer.
BK
====================================

This is the biggest difference in many generic qualities versus a paint like DuPont's. Many painters, shop owners seem to think a cheap generic gallon of paint is more cost effective than a name brand. Not true, it will take more coats of a generic to achieve the same film build thus your costs increase as well, not only that, more solvent is being released into the air with generics.
----------------------------------------------------------------------

Yes there are clears that need 4-6 coats to safely buff, including a few of the lower grades the majors make. Kinda like the one now that is delaminating
if you did not apply enough coats.
Don't categorize all the generics into one group as there are a few good ones out there.
BK
=====================================


FYI to all. When you approach 12-14 mils of paint film, it's time to strip your part or cracking will occur.
------------------------------------------------------------------
True if you are using an everyday production clear of acrylic urethane grade.
There are other ones that are made for this type of mils when doing show care or restoration jobs.
BK
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Old 01-28-2009, 07:57 AM
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I should have put this in the original post...


DISCLAIMER!

This project is not to show "how much you can get away with"!!

YES everyone, you WILL SEE your flaws thru the clear!!! If you fill scratches like I did here, you WILL SEE THEM thru the clear. YES you can bury them, like those funky tables with the coins and crap buried under clear resin at the pizza parlor, you can't feel these scratches, but you can SEE them!

All this test is to provide is a visual proof of how thick clear can get, that is all it is to provide, end of discussion.

YES, you can apply four coats of clear, cut it and buff it, no big deal. It will not fail, it is fine, with most clears.

This is just an example of exactly what is "happening" when you do apply that much.

Brian
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Old 01-28-2009, 11:39 AM
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Quote:
Originally Posted by MARTINSR
...YES everyone, you WILL SEE your flaws thru the clear!!!
That was basically my question...so no need to do the black paint test.

Regarding the Sharpie bleed through. Does it bleed trough with precise edges (equivalent to the original markings) or do the solvents distort the edges and give it a fuzzy looking outline?

The reason I ask is if it does not distort, and only shows the original mark distinctly, it might be a trick one could use for doing some graphics work. (As in drawing on your ghost flames or pinstripes with a Sharpie and then just shooting your bc/cc over the top.)
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Old 01-28-2009, 12:59 PM
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Brian,
just caught a "overhauling" where they did do deep scratches on purpose...
goal was for the silver/grey second body color to look like "brushed" finish metal under the clear...

(I'd screw it up for sure) but Chip used just coarse sandpaper and a block to cut in straight deep scratches on the base coat over whole length of the silver/grey....
then buried it in clear,,,cut and buffed it...

looked good/correct/real on TV so there are some applications for your test results
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Old 01-28-2009, 05:05 PM
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That should look nice in 6 months. The Foose job that is.
Be interestering to SEE what Brians test looks like later.
Custom paint is "custom" for a reason and "if" you plan on playing outside in the rain,be prepaired to get wet.
Scratch=Shrinkage and the less scratch you have,the less shrinkage you get.
It's like doing paint work without filler.The "low" spot will still be there.
Unless you level in stages,your just building the SAME hole.
You may eventually "fill" it up but once everything dries out.You got basically the same surface you started with.
Shine has the best analogy on "scratch".
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Old 01-28-2009, 06:33 PM
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I have to say, the last little "test" I did where I fixed that fender and primed it with the 2K aerosol, it is holding up GREAT! I sanded the filler with 80 grit and then surfaced it with the aerosol then painted it with bc/cc. I put it up on a roof out back and the sucker still looks great! It has been sitting out there since August of last year. Click here for the thread on the filler primer.

I know that isn't the end all to the question, but it is looking pretty good so far.

That all being said, none of that was the reason I did this project. It is ONLY to have a visual example of the filling with a few coats of todays clear.

Brian
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Old 01-30-2009, 05:29 AM
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On the Sharpie issue.
I have cleared over Sharpie signatures without any problems.
Works great for permanently marking things.

Brian, Congratulations once again for sticking your neck out
to offer info. I don't do it anymore for this very reason of
how some wants to nit-pick & twist the info to death.
Thanks, well done.
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Old 01-30-2009, 07:17 AM
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Bee,
illustration only, just for the idea:
80 grit=80 granules to the inch=.0125" size grit

2/3rds of each grit is buried in the resin on the paper so the deepest scratch from the 1/3rd exposed grit should be .004"=approx 1/10 of one mil "low spot" (.09mil?) for shrinkage..

so mathmatically, Brians 6 mils coating should measure close to 5.9 mils on the sanding peaks and 6.1 mils in the valleys when using a good 2 part clear coating....

Foose didn't say what grit he used...
I was just trying to think of a example for why you "would want" the sanding scratch "look" to be magnified by the clear...

somebody check my math,,,I am not awake yet...
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