Actually, every one of those ASTM test methods is used and results just as important for “paint” (whatever that is) as they are for “special coatings coatings” (whatever they are).
Flat vinyl-acrylic wall paints can have wide variances in abrasion resistance and pencil hardness for example; paint (as opposed to what we usually call “industrial coatings or high-performance coatings”) has been in existence for thousands of years as evidenced by ancient cave paintings (don’t we wish some of the stuff we buy today would last as long!).
“Durability” is a word often used, but one really more applicable to the substrate than the coating (although the coating formula has some effect). A stable, relatively neutral, dry substrate like rock is a good surface for paint - hence the survival of historical cave art. Other surviving ancient coatings on flexible surfaces are usually more of a “dye” or “stain” made from an organic penetrating material than a “coating” (Shroud of Turin, anyone?)
You can make a simple water-based paint using water (duh…), Elmer’s glue (or Titebond…or equal…I don’t want to make this a proprietary product), a few drops of dishwashing soap (which is a “wetting agent” that helps the film coalesce and apply smoothly) and…dirt. Take a mortar and pestle and grind the dirt into a fine powder, then blend it together with the other goodies - ta-da! Acrylic Paint. And if you used a glue that was based on a 100% acrylic resin (and enough dirt), it’s most likely going to dry resulting in the following:
100% acrylic low-sheen paint.
It’s going to stick as well as most commercial paints. Depending on the source of your dirt, it may have better or worse corrosion resistance than a commercial water-based metal primer. QUV results will primarily depend on the dirt - some elements fade more when exposed to sunlight than others.
It’s probably a tan color (having done this in the past as part of technical training sessions, my victims…errr, students…ended up with tan “paint” from most dirt sources). But if you got your “dirt” from the black sand beach on the northern tip of Kona in Hawaii, it’d be gray. It would also have outstanding QUV test results compared to most commercial gray “paint”.
But would you specify it?
It’d have lousy corrosion resistance, and if the dirt percentage (the largest part of the “volume solids”) was very high it would have terrible impact resistance and adhesion, as it would not compare well to commerecial paints using a common flexibility test, ASTM D522 - 93a(2008). It would be quite brittle - and that test plus a couple of others are quite critical for ANY film-forming liquid coating, be it “paint” or “special coating”.
In reality even a “simple” flat wall paint is FAR more complicated and will have dozens of components.
This simple example demonstrates how easy it is to make “paint”, but how much flexibility there is in formulation - and how use of some components may compromise performance in one or more areas.
You can’t separate “paint” and “special coatings” and say the quality of the latter can be determined by ASTM test method results but the quality of the former does NOT depend on those same test methods.
The additional dilemma of using ASTM test method results as “standards” is - WHO is going to determine what the baseline result is for each test? The ASTM numbers on paint data sheets are the manufacturer’s own test results (or results from an outside lab). They are NOT standards set by ASTM.
Yet many Architects, Engineers, painting contractors and paint/coating salespeople are led to believe that some particular company’s ASTM test results are actually ASTM “standards”. Specs are written around companies’ products that require submitted (or substituted) products to “meet the ASTM test results of the specified product”.
From a technical standpoint, that’s flat wrong. There is no “right” or “wrong” for most ASTM test results - there are levels (pencil hardness is one that comes to mind) but a higher or lower number is only important if the paint/coating’s specific application requires test results to be within a certain range for proper performance - but again, only in THAT application. When used on a different surface or in a different place, a test result range that was acceptable one place can be totally unacceptable in another.
An entire st of test results has to be carefully balanced to produce a product that does “something” - functions as a wall finish, performs as a ferrous metal primer in a marine environment, is used as a temporary coating, can be applied underwater (yes, those exist) - the paint chemist’s job is to look at all the variables and assemble the most cost-effective group for a desired result.
There are many raw material vendors, many guide formulations for each type of paint/coating and many different approaches to the manufacturing of a single generic product. A variance of one test result may be totally irrelevent - and that test not important in the performance of a particular coating, hence rarely performed - , but “loaded” on a manufacturer’s product data sheet to eliminate competition. Other manufacturers don’t perform the test and won’t have ANY results.
And we have a rejected submittal for an absolutely invalid reason.
It gets even better when the specification requires “certified test results from an independent laboratory” with a submittal or request for substitution; then dog-piled with “…matching ASTM test results on file in the (specifying entity’s) office”.
So not only do non-specified manufacturers have to have tests performed at potentially high cost (plus many of the tests take months to perform, prohibiting a submittal or substitution simply on the basis of time) but they may have to match test results that they can’t see, might be irrelevant, and they don’t even know WHICH tests would need to be performed.
This is why I particularly like the MPI’s approach of determining a reasonable baseline and having all parties know what to expect.
Hopefully MPI will expand their depth into the industrial coatings arena or a similar organization will begin to develop the same type of system.
I hope this didn’t get anyone off track - primarily I wanted to show that ASTM tests are important for ALL paints/coatings, but that one manufacturer’s results cannot be used as a “standard” without very careful consideration of how submittals and substitutions can be fairly handled.