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Adding Clear to Single Stage Urethane (final coats) ?
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Doug C
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PostPosted: Thu Mar 20, 2014 11:34 am    Post subject: Reply with quote

jspbtown wrote:
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I've read one guy who said he never uses more than 25% of clear in the final coat.


Is that your plan or are you considering still doing what you originally said you would? If so...that will be alot more than 25% of clear.


I am more than likely going to try some form of this procedure, be it 25%, 50% or the technique I listed above. Actually maybe all of the above on a test panel first. I am still researching what I can do. It would help if PPG (and others) were more specific about the ratios, but I see no mention of that in their tech sheets. That would most likely be because it doesn't matter, but then we're back to assumptions. When you search paint forums for best single stage black paints.. this subject often comes up. So I will see if I can get a general consensus. I was hoping someone on this site would have tried it before.

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PostPosted: Thu Mar 20, 2014 12:12 pm    Post subject: Reply with quote

[quote="jspbtown"]
Quote:




I am surprised that "Old School Painters" mix and match Acrylic Urethane paints. I did not think they have been around that long.



Well, I don't know if any one would consider me old school, but I've been a bench-top chemist in the mixing room for a long time. Smile More for my own info than for any other reason, I'm not against trying different methods.
Some work, some don't.

Urethanes have been around these parts since at least the mid-eighties. The first time I sprayed Glasurit, I was hooked! Smile
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kman
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PostPosted: Thu Mar 20, 2014 6:33 pm    Post subject: Reply with quote

One trick to create depth is to do a couple coats of single stage then a coat of mixed, and top it with a couple coats of clear. Adding single stage black to the clear on a black car is common. Obviously adding metallic in the clear is a no no for polishing purposes, Though it makes a decent effect. Usually you can just use the clear hardener for both. I once mixed clear with a porch and floor poly to make a kick ass matt single stage on my kitchen cabinets. If in doubt it doesn't hurt to do a test panel to see how it cures and reacts. Could save you a ton of trouble.
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Doug C
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PostPosted: Thu Mar 20, 2014 6:43 pm    Post subject: Reply with quote

kman wrote:
..One trick to create depth is to do a couple coats of single stage then a coat of mixed, and top it with a couple coats of clear. ..


Good to see somebody has heard of mixing in clear with SS paint. Maybe I'll do as you described - that would probably help with the cut and buffing problem that was mentioned earlier.

Still though.. which to use, polyurethane clear (named as optional on the tech sheet - after a dry time) or the high gloss urethane clear (that I found to have similar chemical makeup)?

BTW - here's a curious thing (to me anyway).. on the tech sheet for the "Acrylic Urethane" paint that I've chosen, the sheet describes it as "Polyurethane Enamel Color". Poly Enamel ?!?!? Can someone explain this - Could that be just a typo or is it actually the case, a slight of hand by the paint co. maybe? I just noticed it.

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jspbtown
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PostPosted: Thu Mar 20, 2014 8:56 pm    Post subject: Reply with quote

I had a discussion with a VERY reliable source on this issue this evening. I wanted to share with you what he said. This relates to Kirker paints but may to others as well. I have 100% trust in what he says...100%. I have done some editing for easier reading but this is what in essence he had to say:


"I can’t speak for other manufacturer’s products, but Kirker’s urethane clears are certainly compatible with our ULTRA-GLO single-stage urethane topcoat colors. They work over the color (as you well know), and they also work when the two systems are combined. You must mix the color and the clear separately with their own activators before blending the two systems together. That’s an important step.

Some of the best shortcuts and tricks are developed by the guys who do this day in, day out for years (and scary to think, for some, decades). That’s where this came from. Even before modern urethanes were invented, the old time body shop guys knew they could cheat a little to bring up the gloss and put more clear solids into the top of the film by intermixing a little clear into their color coat. Sometimes, this was done simply to save the effort of having to go around a large vehicle another one or two times shooting clear over the old style acrylic enamels.

But there’s more to it than that. By shooting consecutive layers with “stepped up” levels of clear, you’re able to give a paint job something we call dynamic depth. Say you shoot two coats of straight single-stage urethane color to get a nice solid base. Next coat is 75% color 25% clear. Follow that with a coat mixed 50/50. Next coat is 25% color to 75% clear, then the final coat is 100% clear. When light hits that paint, it’s going to travel deep down into the layers and bounce back at all different intervals and angles (this is called refraction). Even though the paint film is only maybe 3/1,000 of an inch thick, refraction can make it appear much deeper."

Consider this information straight from the horse's mouth.

[/i]
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1966_baja-bug
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PostPosted: Thu Mar 20, 2014 9:06 pm    Post subject: Reply with quote

Yeah you can also clear over performance single stage paint I don't know the steps but i know guys that have Done it, It does make it look a lot better.
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1966_baja-bug
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PostPosted: Thu Mar 20, 2014 9:06 pm    Post subject: Reply with quote

Yeah you can also clear over performance single stage paint I don't know the steps but i know guys that have Done it, It does make it look a lot better.
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Doug C
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PostPosted: Fri Mar 21, 2014 6:12 am    Post subject: Reply with quote

jspbtown wrote:

".. you’re able to give a paint job something we call dynamic depth. Say you shoot two coats of straight single-stage urethane color to get a nice solid base. Next coat is 75% color 25% clear. Follow that with a coat mixed 50/50. Next coat is 25% color to 75% clear, then the final coat is 100% clear. When light hits that paint, it’s going to travel deep down into the layers and bounce back at all different intervals and angles (this is called refraction)..."

Consider this information straight from the horse's mouth.

[/i]


Thank you for that jspbtown - that's a good confirmation for me about the process that I originally outlined earlier in this thread. It's not exactly the same but yes basically the same thing - only big difference is the final coat of straight clear, which probably isn't a bad idea. You didn't happen to ask him how this would effect a final cut and buff, did you? Could you? Again, thanks.

Doug C


Last edited by Doug C on Fri Mar 21, 2014 6:17 am; edited 1 time in total
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jspbtown
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PostPosted: Fri Mar 21, 2014 6:15 am    Post subject: Reply with quote

Doug,

Yes...I actually did ask him. The "discussion" was over email and it was late so I am waiting his response. When I get it I will post it.
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jspbtown
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PostPosted: Fri Mar 21, 2014 8:01 am    Post subject: Reply with quote

So here is the response I got. Remmeber...this is just for the single stage Kirker paints. It may, or it may not, apply to others. It is at least a well founded explanation:

"Yes, the chemical makeup of the two activators may be different, but they’re made of complementary materials. At least between ULTRA-GLO Activator and the clear activators. They’ll work together side-by-side with no issues… but that doesn’t necessarily mean they’ll work in place of one another. The clear and color have different solids content and each requires specific blends and different amounts of isocyanate.

Stoichiometry is the balance of correct isocyanates to fully crosslink all the polyol on the other side of the mix ratio, resulting in a fully cured paint film. I cringe when I hear about guys trying to save a few bucks by buying a generic hardener or activator to use with topcoats or clears, because the technical people have spent a lot of time calculating the correct ratios. It’s funny, when those jobs go south, they never look at the knock-off 4:1 activator they used at 3:1 with the paint… they always blame the paint, even after admitting they didn’t follow instructions and swapped in someone else’s activator. You would be surprised how often that occurs.

Really good point about color sanding into the layers of film. That theory would hold true if you were talking about a candy, where the color develops progressively with the number of coats applied. But take that Performance Yellow you used on the Avenger. The color didn’t change from one coat to the next. It may have appear to at first, but that was only until you achieved full coverage. Bright yellows tend not to give very good hiding, so it probably took a couple extra coats before your paint had 100% opacity. From that point on though, it didn’t matter if you applied one, three, seven or even twelve more coats; the color would not have changed. So, if you were to sand deeper into the surface in one spot, it would not alter the color there.

Now on a metallic or pearl colors like your Bright Orange Metallic Manx… aggressive sanding could be a problem if you didn’t have sufficient clearcoat on top to work through. But that’s a different story than disrupting the dynamic depth effect. Say you used the stepped-up application I described yesterday, but your last coat was 25% color 75% clear. There’s not going to be a whole lot of clear stock to take down before the sandpaper starts to catch the flake (and the metallic particles in that color are huge!). That would cause smearing and all sort of ugly effects. It’s exactly why, even over single-stage colors in the UCB series, it is recommend applying a clearcoat."
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Bobnotch
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PostPosted: Fri Mar 21, 2014 11:48 am    Post subject: Reply with quote

1966_baja-bug wrote:
Yeah you can also clear over performance single stage paint I don't know the steps but i know guys that have Done it, It does make it look a lot better.


Yup, did that on my T-34 Ghia, as the clear and color weren't made to be mixed together (not compatable). Basically (according to the material sheet), you spray it in color, then you wait a 1/2 hour, then clear coat it. Then IF you want, you can wet sand it (after 24 hours) but within 3 days, and either buff it up, or clear coat it again. Very Happy I've done it both ways, and it doesn't seem to be any different than doing a Base Coat Clear Coat paint job. Rolling Eyes The re-clearing it, seems to make the finish a lot smoother though (some here call doing that "drop coating").
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Doug C
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PostPosted: Fri Mar 21, 2014 7:25 pm    Post subject: Reply with quote

jspbtown wrote:

..Really good point about color sanding into the layers of film. That theory would hold true if you were talking about a candy, where the color develops progressively with the number of coats applied.

..So, if you were to sand deeper into the surface in one spot, it would not alter the color there.


Well alright! I understand your source isn't claiming this will work with other paint brands - though I suspect these paints are more similar than different. But this info is certainly helpful and I appreciate you posting it. So I'm reading in his message - that color sanding (cut and buff) would not be a problem with a non-metallic color (which I will be using).

Doug C
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PostPosted: Fri Mar 21, 2014 7:35 pm    Post subject: Reply with quote

[quote="Bobnotch"]
1966_baja-bug wrote:

.. as the clear and color weren't made to be mixed together (not compatable). ..you spray it in color, then you wait a 1/2 hour, then clear coat it..


Hi Bob, what paint was this that you did that technique with? It's kind of strange that the SS you used and the clear are considered incompatible yet only 1/2 hour flash time is all that was required between shooting them. I mean the paint would have still been wet to an extent right? So, it's kind of like the technq we've been discussing. Or, do you mean that it's a clear you chose on your own and wasn't mentioned as an optional clear by the paint mfgr?

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PostPosted: Fri Mar 21, 2014 9:12 pm    Post subject: Reply with quote

I have spotted in restoration shop single stage and final coated with clear mixed in, it helps with the blend a little to.
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Doug C
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PostPosted: Fri Mar 21, 2014 9:46 pm    Post subject: Reply with quote

vdubspeedshack wrote:
I have spotted in restoration shop single stage and final coated with clear mixed in, it helps with the blend a little to.


Hey vdub... which clear specifically did you use when you spot painted with the Restoration Shop SS? That's part of my dilemma right now. Knowing one that has worked with a final "mix" coat would be a big help. Thanks!

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PostPosted: Sat Mar 22, 2014 7:58 am    Post subject: Reply with quote

[quote="Doug C"]
Bobnotch wrote:
1966_baja-bug wrote:

.. as the clear and color weren't made to be mixed together (not compatable). ..you spray it in color, then you wait a 1/2 hour, then clear coat it..


Hi Bob, what paint was this that you did that technique with? It's kind of strange that the SS you used and the clear are considered incompatible yet only 1/2 hour flash time is all that was required between shooting them. I mean the paint would have still been wet to an extent right? So, it's kind of like the technq we've been discussing. Or, do you mean that it's a clear you chose on your own and wasn't mentioned as an optional clear by the paint mfgr?

Doug C


I was using PPG's Concept single stage (reduced with DT 870, and using DCX 81 for a hardener/activator) for the paint, and PPG's Stratoclear 2082 for the clear coat. For the clear I used 2084 activator, as it's a 2 part clear.

The Concept tacks up in less than 10 minutes, flashes in a 1/2 hour and is dry in 4 hours. Shocked The Stratoclear is along the same lines in dry times (tack time is 2 to 5 minutes), but depending on temperature can take up to 8 hours until fully dry (at 70* room temp). Higher temps, equal shorter dry times, or use of a different activator. I've shot it in 70 degree weather (at 8 in the morning), and watched the temps rise during the day and have seen it be dry in 4 hours or less too. But, it's the same with the Concept's reducer, in that I was painting in 72* shop temps (why I used the 870 reducer, as the working temps are 65 to 75* which is the same as the 2084 activator for the Stratoclear).

But IF you read the sheet, it tells you NOT to mix that clear into it. You can use other clears, but I was using that clear, so it had to go on seperately. Rolling Eyes Both are compatible with each other, just as long as they are sprayed seperately. Very Happy
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64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120
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PostPosted: Sat Mar 22, 2014 8:53 am    Post subject: Reply with quote

PPG DCX 2011 clear, but all you have to do is mix a little paint (like a tablespoon) with whatever clear you want to use, with all hardners/activators in a small cup. If they play nice together, meaning they dont start looking like colored cottage cheese instantly, or foaming over like a bad science experiment, then they are compatible. Next pour your cup onto a piece of cardboard and set it aside and let it dry, check it in about 2 hours, should be dry and not tacky, if it is, you're good to go, if not let it sit another hour and check, if still tacky, its probably not going to dry
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Der Speed Shack
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PostPosted: Sat Mar 22, 2014 9:05 am    Post subject: Reply with quote

One other tip with the Restoration Shop paint is go a little less on the reducer than recommend on the label, I believe it's 2:1:1, same as PPG single stage. The difference is RS is a thinner(less viscosity) paint than PPG out of the can. I've found I get more sagging/runs when I mix it to recommended ratios, I'll usually mix it 2:1:.75. Just my experience with Restoration Shop paint, other than that I've had great results.
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PostPosted: Sat Mar 22, 2014 12:13 pm    Post subject: Reply with quote

vdubspeedshack wrote:
PPG DCX 2011 clear, but all you have to do is mix a little paint (like a tablespoon) with whatever clear you want to use, with all hardners/activators in a small cup. If they play nice together, meaning they dont start looking like colored cottage cheese instantly, or foaming over like a bad science experiment, then they are compatible.


Yup, the stuff I was using would start turning to jelly in a few minutes IF combined. Shocked That's why I shot them seperately. I also went back in, sanded again, and re-cleared it all. It gave me the finish I was looking for. Cool
Sometimes it's not really worth trying to "cheap out" when it comes to painting. If you've been doing it for a while, you can cut some corners, but you have to know what you're doing. Most of the time though, you have to do it "by the book", in order to get good results. What works for someone, might not work for you. I've seen it many times over the years. It's really an art form getting paint to spray right. For a first timer, I'd do it as a BCCC paint job, as you'll be happier with the end result. Add in that you're painting a Ghia, and things get a little more complicated. Wink
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Bob 65 Notch S with Sunroof
71 Notch ...aka Krunchy; build pics here;
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64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120
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PostPosted: Sat Mar 22, 2014 2:57 pm    Post subject: Reply with quote

I should also mention that I dont usually mix the clear in my paint for complete paint jobs as you dont need to with acrylic eurothane or enamel
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