TheSamba.com :: View topic - Adding Clear to Single Stage Urethane (final coats) ?

Tue Mar 18, 2014 10:36 am

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

Tue Mar 18, 2014 4:04 pm

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

Tue Mar 18, 2014 4:22 pm

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

Tue Mar 18, 2014 6:22 pm

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

Wed Mar 19, 2014 6:35 am

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:

Wed Mar 19, 2014 11:26 am

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

Wed Mar 19, 2014 12:32 pm

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.

Wed Mar 19, 2014 1:17 pm

jspbtown wrote: 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.
Yep, pretty true.
When I mixed clear with single layer it was almost always to get better metallic orientation with a difficult colour, so I could control the metallic a little better and let the clear take care of the needed gloss.
I really don't think mixing clear with a quality line of single layer non-metallic colour will give any more depth, or DOI (distinctiveness of image).
I hear a lot of people talking about specified number of coats, but really, the way I've done it for years (30 to be exact) is to paint until coverage is achieved and then one more for sanity's sake. The industry standard is three coats for single layer... too much product can lead to problems such as crater-sized stone chips, crazing as the solvents leave, solvent popping, and de-lamination.

Mike

Wed Mar 19, 2014 1:26 pm

Quote: When I mixed clear with single layer it was almost always to get better metallic orientation with a difficult colour, so I could control the metallic a little better and let the clear take care of the needed gloss.

That was very true on two of the three cars I posted. The blue and the orange ones were metallic and I could "dust" on some paint to get an even distribution of the metallic particles. I then got my gloss with the clear.

Wed Mar 19, 2014 1:50 pm

Tram mixes paint & clear with paint he buys at NAPA.

Wed Mar 19, 2014 2:25 pm

jspbtown wrote: Well just by looking at the MSDS sheets they appear to be different in makeup. ..
... On a single stage paint system once you achieve coverage you are not adding any depth or shine...

jspbtown - Not being a smart arse here, but I realize that the chemical make up isn't going to be identical between the hardeners and activators but my understanding is that some chems clash and some will "work" together. Can you please elaborate on what has you of the opinion that these are too different in makeup. From the the chemical compositions listed on both of the MSDS sheets I see that BOTH share approx. the same amounts (weight %) of Butyl Acetate, Aromatic Naphtha Light, Trimethylbenzene, Proprietary Resin and Methyl Ketones. There's nothing else listed really. I don't know it all, and so that's why I'm asking.. maybe the Methyl Ketones are slightly different (two are listed on 1 MSDS and one on the other), and would cause problems?

You would be adding 'depth of shine' by mixing clear to a single stage paint at the end - not so if adding base to the clear of BC/CC though. There's a difference.

Doug C

Wed Mar 19, 2014 2:34 pm

CanadianBug wrote:
..I really don't think mixing clear with a quality line of single layer non-metallic colour will give any more depth, or DOI (distinctiveness of image).
Mike

Well from what I understand this is pretty standard procedure for 'old school painters' (lol, whatever that means) who are doing single stage Black cars to a show quality level. Supposedly this really deepens the look. This was the subject line where this technique came to my attention in other forums. I'm not a member of those forums and don't care to become one, just to ask a single question. I hoped someone here had heard of it. I may try it anyway.

Doug C

Wed Mar 19, 2014 3:17 pm

Quote: but I realize that the chemical make up isn't going to be identical between the hardeners and activators but my understanding is that some chems clash and some will "work" together.

I guess that is my point. Lots of things are made up of similar products but the outcomes can be very different by the percent of an ingredient used.

I would "assume" that the paint manufactuer mixes the chemicals at certain ratios for a reason for each product. Maybe the paint needs more of a certain chemical to harden? Maybe the clear needs a certain amount of one chemical to level better. Maybe it has to do with the process of hardening. I really don't know.

So if you assume that they are created differently for a reason you have to ask yourself what are the possible outcomes of using them as not directed? I can tell you that as an amateur (all my stuff is garage done from start to finish) painting is a very precise art. So many things can go wrong that will cause runs, blisters, lifting, fisheyes, solvent pop, fogging (and on and on and on) that any variations in mixing is just asking for problems.

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

If you want to try it then I suggest a test panel. That way if you have a problem you won't have wasted all your time and money by painting the whole car. Of course this will just show any immediate incompatibility issues and not something that might show up down the road like delamination or fogging.

Wed Mar 19, 2014 6:18 pm

jspbtown wrote: ..I would "assume" that the paint manufactuer mixes the chemicals at certain ratios for a reason for each product. ..

So if you assume that they are created differently for a reason ..

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

That's a great suggestion about the test panel, I will indeed spray out a test before trying it on my car.

As far as assumptions go - your theory probably IS right BUT my first assumption is to believe it's so they can make and sell a whole other product (the optional clear that they suggest in the tech sheet). It forces the user to buy a different product IF extra durability, fade resistance and shine is desired. Again the hardener for the optional clear looks a lot farther off on the MSDS sheet - yet it's meant to be used with this particular SS paint.

BTW - PPG's SS paint (concept) makes two suggestions for optional clears in their tech sheet. One is to do the technique that I am thinking about doing, outlined above AND the other is a clear sprayed separately after paint dries for a while (like TCP does). So, it's not unheard of. And kind of coincidental too.

As for the 'Ol Skoolers I think they've been doing this with lacquers, enamels and all SS paints, not just urethanes.

Doug C

Wed Mar 19, 2014 6:27 pm

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

Wed Mar 19, 2014 8:49 pm

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.

Wed Mar 19, 2014 11:06 pm

jspbtown wrote: ..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? ..

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

The color sanding question would need to be answered by someone with experience doing this technique (Im still researching it) or by a PPG rep. BTW- I just noticed that the same method of adding clear to the final coat is also mentioned in PPG's Omni line (MTK AU).

Also, the optional clear that is recommend on the tech sheet (for use after dry time) is called "Polyurethane" clear while the clear that I'm thinking I can add to the paint is just called "Urethane" clear. The paint itself is urethane. I've always thought of polyurethanes to be a plasticy looking top coat on various surfaces. That's no proof, but seems to fit IMO.

Doug C

Thu Mar 20, 2014 8:40 am

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).

Thu Mar 20, 2014 9:11 am

Quote: 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.

Thu Mar 20, 2014 11:23 am

Q-Dog wrote: .. To me, "old school" means no clear coat.

But how many painters (or Auto Restorers) of any era refuses to use what the client requests as long as it pays the bills? If a client wants BC/CC that's what they get. Few refuse the work - doesn't make the older ones any less 'old school' in my mind.

I feel like this technique would have originally been tried by someone looking to get an advantage on their own showcar w/SS paint (for originality). I could see an old painter trying this, maybe on their own car when clears were first introduced. That would have made the old schooler an innovator at the time. Then again.. maybe no one ever thought of the idea until some lab technician for a paint company decided it might be worthwhile.

Doug C