[Mahler9th]

I have a 1975 911 race car that was painted in 2001 with a PPG singe stage. At the time, the PPG paint code was L80k/"Guards Red." I am pretty sure that PPG's version of L80k was cross labeled as 027 at that time.

Just last year I bought two quarts of the same PPG paint with the same codes.

The new paint did not match what was on the car (and the paint was $200/quart, ouch). However the leftover 2001 paint did match what was on the car. The 2001 and 2013 paints had the same PPG color codes: L80k/027.

What I think is happening is that aftermarket paint suppliers (like PPG and those that make touch up paints as well) have formulations and/or tint ingredients for different paint codes that change over time, and in any case are intended to be their "best effort" to match what was shipped by PAG. But they cannot be an exact match in every instance.

So what I learned, as has been suggested here, is that for optimal results it is best to work with an expert who can use an existing "sample" to slightly tweak the manufacturer's mix for the best match.

In my case that was easy, as I could take my paint supplier a small fiberglass part. He did an excellent job , and even mixed my old remaining paint up with his custom matched version so I did not have to toss it.

He is an absolute expert (he has also done some matching work for valuable old factory race cars including one with /30 in its name).

I think all of this is a "value adder" in body repair and paint supply businesses.

So to me, color dial in by a professional will be mandatory from now on with automotive paints. And if I ever used a touch up product, my first choice would also involve whatever aerosol I could get from a pro resource who can try to dial in the color as close as possible.

If I did buy something more generally available as a touch up or scratch repair product, I would do some sort of test first to make sure the final result would meet my requirements for matching.