The search for a Plasti-Kote GM7173 equivalent...

[AnubisGuard]

EDIT: Ignore the rest of this thread. I'm keeping it for posterity, but we found what appears to be the factory color code for 7173. It's a 1984 Pontiac code, W15 Silver Sand Poly, aka WA8311. I bought a dealership color chip book from 1995 and compared my samples of 7173 and out of all the General Motors colors that chip was very, very close. See here for Tripper 's real-world results with that code; it's nigh-on identical.

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A long overdue order of tricorder electronics from GMProps is (finally) on its way, and this has triggered a bit of an obsession: how best to paint the body once the body kit gets here? After trying out a few of the most common substitutes - Med. Marblehead Metallic, Med. Charcoal Metallic, and Precision Gray - I wasn't happy with any of them; Med. Marblehead is too light and not brown enough, Med. Charcoal is too dark and too blue, and Precision Gray is way too blue. The only other good substitute I know of was found by Dreamscape, and it's not available in the US. So with a bunch of cans of Duplicolor from my local O'Reilly's I set out to get as close as possible to the samples of real 7173 I have. All these Duplicolor colors are still available, and I'll put mixing ratios at the end of the post, so anyone who wants to recreate the color can.

A few things to note: real 7173 varied quite a bit. I have props I painted across the span of a couple years, and they vary from very brown, to very silver, to almost purple. 7173 has a slight but noticeable color shift, from neutral silver highlights, to copper-brown midtones, through almost lavender shadows. This was something I did my best to capture. I compared against a couple different samples I have and settled on a color somewhere in the middle of them.

After a lot of trial and error, I settled on Precision Gray, Universal Silver, Med. Garnet Red, and Copper Wheel Coating as the base colors.

I sprayed each of them into a jar, keeping count of the number of seconds I sprayed each. A few dip tests later and see what you think (the dark specks are bubbles from dipping the spoons).

Against a 7173 sample circa 2002:

Against a 7173 sample from a year or two later:

The final ratio, adjusted a bit for wastage, is:

Precision Gray: 56 to 57 parts
Universal Silver: 23 to 24 parts
Copper: 10 to 11 parts
Med. Garnet Red: 1 part



It's perhaps a touch too purple/lavender still, so less Garnet Red may be called for.

I've ordered a Preval refillable spray canister and it should be here next week.

What do you think, sirs?

 

[Dreamscape]

That's pretty damn close. But as you say, I think it needs less Garnet Red. I'd maybe try your ratios with a quarter of a part Garnet Red to start with. Then if it's still too blue/cold then increase to 1/2.

 

[AnubisGuard]

Yeah. I'm also thinking that the Precision Gray may just be too blue and that in mixing with the copper it makes a kind of purple. Thinking of switching it out for the Med. Charcoal Metallic and seeing what difference that makes.

 

[AnubisGuard]

Added a lot more gray, silver, and copper to the mix:

And the old v.s the new. Old on the left:

I wound up at

Precision Gray: 122 parts
Universal Silver: 44 parts
Copper: 33 parts
Med. Garnet Red: 1 part

I could have kept going, but I ran out of silver.

EDIT: and just for fun, here it is against a bunch of different samples of 7173 across the years.

 

[Tripper]

looking good! I would say it still seems an ever so slight bit skewed red/pink

 

[AnubisGuard]

Yeah.

I went back through my other tests and, on reconsideration, I was closer with this Med. Marblehead/Med. Charcoal/Copper/Med. Garnet Red mix:

I'll need to wait for my next can of Med. Marblehead to arrive before I can mix more. But it was an easier mix than this one, and didn't seem so sensitive to exact ratios.

Edit: it's roughly 3 parts Med. Marblehead, 1 part Med. Charcoal, 3/4 part copper, and a tiny splash of garnet red, proportionally about a drop's worth.

 

[Mr Mold Maker]

Your color mix looks spot on!

Just a suggestion if I may.. Instead of spraying and trying to count, you can decant the paint from the spray cans into glass jars and give yourself a much more controllable way to custom mix. The process is basically leave the cans to sit undisturbed for 24+ hours, then you turn it upside down and pop a small hole in. Let the propellant escape, and then cut the bottom off and transfer the paint into a glass jar. Don’t screw the lid on completely, it will continue to degas for a day or two.

But once you’ve done that, you can pull from those jars with a dropper and get it figured out down to the exact mix. I have to custom mix colors a LOT and use this process pretty frequently. It gives you total control.

 

[AnubisGuard]

Just a suggestion if I may.. Instead of spraying and trying to count, you can decant the paint from the spray cans into glass jars and give yourself a much more controllable way to custom mix. The process is basically leave the cans to sit undisturbed for 24+ hours, then you turn it upside down and pop a small hole in. Let the propellant escape, and then cut the bottom off and transfer the paint into a glass jar. Don’t screw the lid on completely, it will continue to degas for a day or two.

Does that work for metallic paint? Wouldn't the metal flake settle and fail to decant?

 

[Mr Mold Maker]

Does that work for metallic paint? Wouldn't the metal flake settle and fail to decant?

I’ve not had any issues with that. Leaving it sit just helps the solvents rise out and helps you lose less paint in my experience. When you turn it over to pop the hole you want to do it slowly and carefully.

However, if any of the flake did settle out you can simply scrape the bottom of the can with a Popsicle when you cut it off and add anything that’s settled back to the jar.

I transfer the metal balls right into the jar as well and shake well before using of course.

 

[AnubisGuard]

What's the best way to punch the hole? Drill? I must admit the idea makes me a bit nervous.

 

[Mr Mold Maker]

What's the best way to punch the hole? Drill? I must admit the idea makes me a bit nervous.

Honestly I just use a little hook tool. Hold the can in one hand and the tool in the other. A little pressure is all it takes. It’s really not anything to be nervous about, just pop a tiny hole and let the propellant out. The can will depressurize quickly and you can get snips in that hole to open it up. Move to a jar.. and then you’re free to custom mix, thin, airbrush, etc.

Here is the actual tool I use as well as a handful of jars I had close by. These were all done as I described. The filler primer was done yesterday in fact.

 

[Jedi Dade]

Her's a suggestion... if you have something that is the correct color - take it to an automotive paint supply place and have them color match it. it will cost a bit as you have to buy minimum of a pt of paint for around $50... but you should also have a paint code for it should you need more. Just a thought.

Jedi Dade

 

[AnubisGuard]

But this is so much more fun!

(I should have done that, but foolishly assumed I could make my own for less. Not turning out to be the case.)

 

[Mr Mold Maker]

Her's a suggestion... if you have something that is the correct color - take it to an automotive paint supply place and have them color match it.

Jedi Dade

That’s a great suggestion, but unfortunately metallics are notoriously hard to color match.

 

[AnubisGuard]

There's also a satisfaction to be found in doing it yourself.

I've probably sunk about $80 or $90 into this at this point, and I plan to keep on going until I nail it with a simple, repeatable formula.

Next up: Duplicolor Anodized Orange. No metal flake, and it appears to be a much redder orange than the copper. I'm hoping I can eliminate the Garnet Red entirely with this, as well as avoid the yellow highlights I've been getting from the flake in the copper wheel paint. (7173 has pure silver metallic highlights; far as I can tell, the brown/warm color is entirely confined to the transparent medium the metal flake is in.)

 

[Jedi Dade]

That’s a great suggestion, but unfortunately metallics are notoriously hard to color match.

True - but its what these guys do... I think you might be pleasantly surprised at what they can match.

Jedi Dade

 

[Mr Mold Maker]

True - but its what these guys do... I think you might be pleasantly surprised at what they can match.

Jedi Dade

I have gone through the process many times. I think you’d be unpleasantly surprised just how far off they can be. Even on simple colors where we know the paint code. Nissan’s Merlot Red was one that I ordered three cans of and each can was different.

Anyways, apologies for drifting the thread slightly off course Anubis. Wish you the best of luck with it!

 

[AnubisGuard]

On a whim, I searched Google and eBay for the GM color code for 7173, variously GM15, GM929L, WA929L and GM Cashmere Metallic. Lo and behold, there's a lot of no-name brands that still make and sell that paint code. They're kind of expensive, around 30 to 35 bucks for a 12 oz can. One seller has 5 oz cans for $18; I've ordered one of those and I'll report once it gets in.

(Duplicolor also makes a GM15 Cashmere Metallic, but it's only available in the form of a 0.5 oz touch up pen. The cap color looks spot on in photos, though.)

 

[Tripper]

Intriguing, looking forward to the results with this new find

 

[AnubisGuard]

Intriguing, looking forward to the results with this new find

Not even close.