Adding Clear to Single Stage Urethane (final coats) ?

[Doug C]

I've read on other forums where guys have added in a mixture of clear to their final coats with single stage Acrylic Urethane paint. This supposedly deepens the shine and I was wondering if anyone here has any experience doing this..

My concern is - since the AU single stage paint and the "high gloss urethane clear" use different hardeners.. would that create a problem? Would the paint's hardner be used only.. or a combo of the two?

Right now I'm leaning towards using TCP Global's Restoration Shop SS AU paint, and I guess their 'high gloss urethane clear coat' (RC 4200). I'm obviously on a bit of a budget but I generally like the idea of adding the clear and would like to try it.

Doug C

[Doug C]

I figure being able to add clear to the final coat(s) of my Single Stage acrylic urethane paint job is going to come down to whether the hardeners/activators are compatible. These two look pretty similar to me (their compositions per MSDS sheets), BUT I really don't know what I'm looking at with these numbers (and 'science lab' names).. can someone here take a look and tell me if you think that are essentially the same stuff?

This is the MSDS for the paint's "acrylic urethane hardener":
http://www.tcpglobal.com/restorationshop/msds/msds_au4001.pdf

This is the MSDS for the clear's "Urethane Activator":
http://www.tcpglobal.com/restorationshop/msds/RH4201%20MSDS.pdf

Thanks in advance.
Doug C

[CanadianBug]

I've done it before, works well if you're spraying a metallic single layer.

What I do is mix the clear (hardener and reducer), mix the single layer (hardener and reducer) and then mix the two mixtures, stirring it well.

It's always best to mix up a small amount to make sure everything is compatible.

It can make a difference if repairs are needed in the future, so keep that in mind.

Mike
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[Doug C]

I will be shooting a non-metallic color (Ferrari's Grigio Medio). Not only is this method supposed to be good for depth of shine with SS paint but also for fade resistance, added durability and longevity - which I like too.

yes I've read that you should mix them in separate cups, letting them get cozy with their respective additives for a few minutes before combining the two. I've heard this called "cocktailing" but I can't find much info on it. Just wanted to be fairly certain that the solvents and what-ever-else (chemical wise) would work together. But then again, they are both Urethanes so you'd think it'd be ok.

BTW, the tech sheet for the paint I'm buying does mention an optional clear that can be used (yes with the SS!!).. but only as a top coat by itself and after at least 4 hours of drying time has passed. But the hardener for that clear does not look (to my untrained eyes) to be as close to my paint's activator/hardener chemically. This has led me to a different clear in the same paint brand and line with closer looking numbers chemically (see link to it's hardener above) to my paint.

Doug C

[jspbtown]

I have used the single stage Kirker paints and a clear top coat with good results. You do not need to wait for 4 hours. You can apply the clear after a good flash (slightly longer than between the SS coats).

Some examples:

[Doug C]

Those came out fantastic! Did Kirker's tech sheet suggest a wait time for the clear or give any other instruction regarding an optional clear?

However, I will not be doing a clear by itself.. The method I'm contemplating is this:
-shoot 2 coats of SS paint first.
-then mix clear in a separate cup and set it to the side
-mix my 3rd coat of SS paint and spray half of it.
-add half of the clear I've mixed to the remainder of the SS color in the gun
-spray half of that as the 4th coat
-add the last half of the clear to the remainder in the gun again and shoot it as a 5th coat.

For getting the deepest shine out of single stage paint, this way there is color as part of every coat. This is essentially the way I've seen it explained a couple of times in my research. It still leaves questions though - like "spray 1/2 of it", which would not necessarily cover the entire car I'm thinking. Maybe just mixing up a half amount of color to start with for the 3rd or 4th coat is the thing to do, and add the half of clear to that.

Either way I wish someone could take a look at the MSDS sheets that I posted above and give me some idea if they seem compatible. Anyone?

Doug C

[jspbtown]

Well just by looking at the MSDS sheets they appear to be different in makeup. I don't think anyone here has the chemical background to tell you if they will interact inappropriately or not. I personally would not risk mixing those together.

I have heard of this method but I really don't see the need for it. BC/CC aren't sprayed that way. The Kirker site advertises useing a clear as a higher level of UV protection and for added durability. I don't know how much extra "shine" you get out of something by adding more color to it. On a single stage paint system once you achieve coverage you are not adding any depth or shine. Its not like a laquer or a candy.

[CanadianBug]

[jspbtown]

[Mike Fisher]

Tram mixes paint & clear with paint he buys at NAPA.
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[Doug C]

[Doug C]

[jspbtown]

[Doug C]

[Doug C]

Just to highlight the point that this is an acceptable known and used technique for adding clear to SS paint - Here's what it says on the tech sheet for PPG's Concept (AU Single Stage paint) regarding optional clear as I'm wanting to do it:

Option 2* - Clear mixed with the last coat of DCC color
· Ready-to-spray (RTS) DCU2002, DCU2021, DCU2035 & DCU2042 with DCX Hardeners can be mixed with RTS DCC Color with DCX Hardeners.
· RTS DCD35 can be mixed with RTS DCC Color with DU Hardeners.
· RTS DCU2002 & DCU2021 with DFX11 Hardeners can be mixed with RTS DCC Color with DFX11 Hardeners.
* For best results allow 15 – 20 minutes flash before mixing clears in last coat.

The PDF is here:
http://us.ppgrefinish.com/PPG-Refinish/Products/Automotive-Refinish/Deltron

Doug C

[jspbtown]

Just wondering out loud......maybe I have a point..maybe I don't...but I will throw it out there.

So in essence as you dilute the color with clear you are getting a lighter and lighter shade of the color? I would think that one of your coats will be some diluted color and mostly clear right?

So how would this work with color sanding? It you don't take exactly the same amount off from everywhere will you have changes in shade or color?

With the standard Single stage you don't have this because you never sand through coverage. With a clear on top you are just sanding through levels of clear. I know that when you sand through all the clear and hit single stage color it looks funny (don't ask how I know!)

So with your test panel I would give it some color sanding too to see if you get color variations.

[Doug C]

[Q-Dog]

After sitting through many hours of OSHA safety training I would like to caution you about using the MSDS for anything other than its intended purpose. The Material SAFETY Data Sheet is to inform the end user of the chemical content of the product in relation to human and environmental toxicity, flammability, etc. I would not use it as an indication of compatibility with other products.

Like you I would assume mixing similar products can work, BUT I would also assume a change in the mix amounts could cause the entire batch to flash too soon, or maybe not harden at all. I would check with the manufacturer to be sure ... a phone call is cheap.

Obviously, as you have discovered, some painters use this process. You just need to find a color coat and clear coat that are compatible when mixed. Unless you want to mix some things together and see what happens, it seems it would be easiest to stick to combinations that your research shows are known to work together or that the manufacturer says will work together.

Also, I am NOT a painter. To me, "old school" means no clear coat. I had my convertible done with single stage, then sanded and buffed (though I can't tell you what paint they shot).
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[jspbtown]

[Doug C]