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#1
Old 04-03-2013, 09:46 AM
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How close does computer paint matching get?

I had some antique signs repainted. I asked them to match the original colors, and they said they could do that with a computer gadget. They kind of looked OK in the poor lighting of his shop, but they looked a bit off when I finally unloaded them from my truck a week later and saw them in sunlight. I pried up a gasket to see the original paint, and it's not even close.

So is computer matching really that bad, or did someone fuck up at some point in the process? What do I do now? I'd rather not deal more with the same guy that made that kind of error, but at the same time I'd wonder if he'd give me a discount at trying again. I'd think that since they've been sandplasted, and primed and have a smooth intact paint coat now it would be fairly simple just put another coat on. There actually is a commercial spray paint that is a very close match, but spraypainting something is beyond my skills.

I guess generally speaking I'm not good at knowing when to take your losses and when to complain to people about stuff.
#2
Old 04-03-2013, 10:00 AM
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Unless you were given a guarantee that the paint would match you don't have anything to complain about. Your sign was painted, and probably with a color you approved. It just wasn't the right one. Computer matching can be extremely accurate, but I doubt your local paint shop used the kind of equipment necessary to do that job correctly, and even if so done, the paints are then hand mixed and slight inaccuracies in measuring can make a big difference, especially if the paint shop uses the wrong base as was done to me one time. To do this properly for your situation a sample would have to be painted first, allowed to dry, and then matched to the original, and the formulation adjusted until the results are correct.

So go back and complain and maybe you'll get a small discount, or maybe you'll find this guy took some pride in his work and the discount will be large, but he might just say "Sorry, you approved the color I was using".
#3
Old 04-03-2013, 12:55 PM
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I've gotten paint matched (automotive paint) and it's been a perfect match, even two different brands at different times (Dupont or PPG)

The hardest part is finding a large enough and flat area to sample. Then you need to gently polish the paint to remove the top layer of oxidation and get down to virgin paint.

I don't know what happened with you, he might not have polished the paint down...the color can change quite a bit over the years between fading and staining.
#4
Old 04-03-2013, 01:46 PM
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I would have understood if the paint was faded or oxidized, but it was a metal electrical sign, and the inside had paint that looked brand new having never been exposed to the elements, and I specifically asked that the matching be done from the inside. (I also asked that the original parts that he fabricated replacement for be returned, which he didn't do)

Last edited by Mdcastle; 04-03-2013 at 01:47 PM.
#5
Old 04-03-2013, 02:20 PM
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My projects have been old industrial/agricultural equipment, so we're working with similar stuff at least.

If it's as off as you say, I wouldn't be afraid to pitch a bitch, well, politely at first. You paid for a service and are not satisfied.

Last edited by Deereman; 04-03-2013 at 02:23 PM.
#6
Old 04-03-2013, 03:03 PM
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http://i699.photobucket.com/albums/v...n/IMG_2387.jpg
http://i699.photobucket.com/albums/v...n/IMG_2390.jpg

Showing how much darker it's supposed to be
#7
Old 04-03-2013, 03:09 PM
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Quote:
Originally Posted by Deereman View Post
If it's as off as you say, I wouldn't be afraid to pitch a bitch, well, politely at first. You paid for a service and are not satisfied.
My experience with computerized paint chip matching was that the folks at the paint counter gave me lots of caveats about the accuracy of their system (or lack thereof) and they advised me to buy a small amount to start with in case it wasn't a great match.

When I tried it, it was clearly darker than the rest of the wall, but I had a bit of white paint around and mixing a little white in worked like a charm. Or at least to my satisfaction.

Note that this was house paint, not automotive paint.
#8
Old 04-03-2013, 07:23 PM
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My experience has been that for light colors, the color matching is dead on perfect. As the colors get darker it becomes a little dicier, but still only noticeable if the two colors are side by side. Even on walls, if you switch colors at one of the corners, you won't notice the difference.
#9
Old 04-03-2013, 10:19 PM
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My guess is that something that might match well in certain lighting won't necessarily match well in very different lighting.
#10
Old 04-04-2013, 12:01 AM
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Hmmm... my guess would be that as long as you are comparing two colors to see only if they are the same color, and you're looking at them in the same light, then the lighting itself wouldn't matter.
#11
Old 04-04-2013, 12:12 AM
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Yes, it will. Light deficient in particular wavelengths, like blue, for instance, will make different colors look very similar. Ever try to tell the difference between a blue car and a green one under an orange sodium vapor light like they use in cheap streetlights and parking lots?
#12
Old 04-04-2013, 02:11 AM
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My one experience, with WalMart, has been that the computer matched the sample with the new paint 100% perfectly.
#13
Old 04-04-2013, 02:57 AM
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Quote:
Originally Posted by El Zagna View Post
Hmmm... my guess would be that as long as you are comparing two colors to see only if they are the same color, and you're looking at them in the same light, then the lighting itself wouldn't matter.
I've found that it makes a big difference what lighting you're in. The only way to be sure if something matches is if you're in sunlight/natural light. Indoor lighting makes it very hard if not impossible to tell at times.
#14
Old 04-04-2013, 07:51 AM
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Depending upon the pigments you may get a perfect match, or a match that only works in one light. The question really coming down to whether the paint to be matched uses the same pigments as the paint doing the matching. If they don't you can be assured of trouble, and probably an inability to get a satisfactory match. Trying to match a vintage paint could be a problem simply because the base pigments are now different. They way the eye perceives colour is sufficiently messy that you can get two colours of paint that appear identical in one light, yet look quite different in another, a phenomenon called metameric failure.

The computer matching system will probably use a standard illuminant (likely a standard daylight 6500K) and will look at the spectral response and map it to a colour, then see if it can find a pigment combination that matches that colour. The weasel word in this is the "colour" it maps to. This is defined by three numbers only, and is not the full spectral characterisation of the paint. It is only meaningful for one light source. If the old paint is made with the same sorts of pigments as the new paint, there is a good chance that the pigment mix chosen will actually be a clone of the old paint, and the colour will match perfectly. But if the old paint's pigments are fundamentally different, there little chance (and indeed it may be intrinsically impossible) for the new paint to match the old one under all light conditions.
#15
Old 04-04-2013, 08:43 AM
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The sheen will often make a difference in how a color seems to look. A glossy dark blue will look different in some lighting conditions from the same dark blue pigments in a flat sheen.

What I've noticed in paints (alkyds, lacquer, and latex) for residential remodel (one of my businesses), is that the machine will often be very close, but having a trained eye tweaking it will get it virtually indistinguishable. And the trained eye person needs to figure out the sheen. Stains are another issue because of different variables of the staining/finishing process.
#16
Old 04-04-2013, 01:06 PM
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Quote:
Originally Posted by Francis Vaughan View Post
Depending upon the pigments you may get a perfect match, or a match that only works in one light. The question really coming down to whether the paint to be matched uses the same pigments as the paint doing the matching. If they don't you can be assured of trouble, and probably an inability to get a satisfactory match. Trying to match a vintage paint could be a problem simply because the base pigments are now different. They way the eye perceives colour is sufficiently messy that you can get two colours of paint that appear identical in one light, yet look quite different in another, a phenomenon called metameric failure.

The computer matching system will probably use a standard illuminant (likely a standard daylight 6500K) and will look at the spectral response and map it to a colour, then see if it can find a pigment combination that matches that colour. The weasel word in this is the "colour" it maps to. This is defined by three numbers only, and is not the full spectral characterisation of the paint. It is only meaningful for one light source. If the old paint is made with the same sorts of pigments as the new paint, there is a good chance that the pigment mix chosen will actually be a clone of the old paint, and the colour will match perfectly. But if the old paint's pigments are fundamentally different, there little chance (and indeed it may be intrinsically impossible) for the new paint to match the old one under all light conditions.
Thanks for the info, and the technical term!

In particular, things can look dodgey under white LEDs. Normal white light has a broad spectrum. White LED light has 3 or 4 very narrow spectrum components, balanced to look white. But when you use it to look at colors produced by fairly narrow-spectrum pigments, you can get odd results.

For a similar reason, you can't use traditional gels with LED spots, in stage lighting. The gels (colored filters) just don't have the same effect on the LED light that they would on broad spectrum white light.

However, we have LED white lights indoors, and I haven't noticed any serious oddness in the colors of things. On the other hand, I'm used to colors simply looking different indoors and under artificial light than they do outdoors, so maybe it's there and I just don't notice it.

LEDs are the worst case, being monochromatic. But I believe we can see similar issues with any light source that's not fairly broad-spectrum and fairly flat.
#17
Old 04-04-2013, 01:10 PM
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Quote:
Originally Posted by NoClueBoy View Post
The sheen will often make a difference in how a color seems to look. A glossy dark blue will look different in some lighting conditions from the same dark blue pigments in a flat sheen.
Yeah, that too. I don't know quite why that is, unless the sheen reflection also has a color component to it that's different from the pigment. But that doesn't quite make sense. Still, I'm pretty sure I've seen what you're talking about.
#18
Old 04-04-2013, 01:32 PM
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Quote:
Originally Posted by Learjeff View Post
Yeah, that too. I don't know quite why that is, unless the sheen reflection also has a color component to it that's different from the pigment. But that doesn't quite make sense. Still, I'm pretty sure I've seen what you're talking about.
I'm not sure about this, but I think the sheen can cause the paint to reflect or absorb colors at different angles from the light source. Industrial color measurements use carefully selected white light, as relected from a block of barium(?) IIRC.
#19
Old 04-04-2013, 01:39 PM
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Quote:
Originally Posted by Mdcastle View Post
I had some antique signs repainted. I asked them to match the original colors, and they said they could do that with a computer gadget. They kind of looked OK in the poor lighting of his shop, but they looked a bit off when I finally unloaded them from my truck a week later and saw them in sunlight. I pried up a gasket to see the original paint, and it's not even close.
I'm not sure your methodology is correct here. Did you have them match the area under the gasket in the first place? Because that area has been protected from fading and sun, while the area they tested may not have been.

Last edited by Finagle; 04-04-2013 at 01:39 PM.
#20
Old 04-04-2013, 01:52 PM
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Back to the OP, I think you should give the guy the opportunity to make it right.
And what did he offer as an excuse for not saving the old parts as agreed? That would upset me too.
#21
Old 04-04-2013, 01:55 PM
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Md, is there some possibility that you have a problem making good choices for providers of goods and services?
#22
Old 04-04-2013, 01:57 PM
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The original paint was 1960s era semi-gloss enamel, if it's relevant.

The inside which I asked them to match should have never been exposed to the sun, as it was protected by electrical components from the sun and rain.
#23
Old 04-04-2013, 01:59 PM
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Originally Posted by TriPolar View Post
Md, is there some possibility that you have a problem making good choices for providers of goods and services?
Judging by my number of my threads, yeah it's a problem. I also have a whole long sob story about how it took three mechanics to fix the heat on my car, and the third one botched it which eventually resulted in the heat going out again, as well as the water pump and radiator.
#24
Old 04-04-2013, 02:06 PM
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I didn't say anything about the parts, the agreement was part "A" could be fixed, "B" he would use as a template for fabricating a replacement (although he said he'd return it, he might have needed to disassemble it to replicate it). I wasn't able to tell that the first was also a fabrication until I took a screw out at home and saw that the hole had been drilled a little bit off and then corrected, so I assumed the first actually couldn't have been bent back into shape. He did a good job on fabrication anyway.

I did email him politely informing him of the problem on the excuse that I just wanted to know what happened, so to give him a chance to make an offer if he wants. Antiques are a new hobby of mine and I'm starting to understand the amount of work, money, and issues involved.

Last edited by Mdcastle; 04-04-2013 at 02:07 PM.
#25
Old 04-04-2013, 02:22 PM
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Originally Posted by Mdcastle View Post
Judging by my number of my threads, yeah it's a problem.
Maybe this should be the topic of your next thread. I've had that problem at times. Usually because I'm placing convenience or price above quality. When I want something done right I know it's going to take some extra effort on my part to find the right guy for the job.
#26
Old 04-04-2013, 02:52 PM
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We color matched something and the results were pretty much perfect.
The guy who did it (though kind of surly and un-nice) did a good job. He dabbed a bit on some paper, let it dry and compared it to the sample right there in the shop before we bought the paint.

We might have simply been lucky.
#27
Old 04-04-2013, 04:18 PM
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I don't think you need to make excuses when dealing with results you aren't happy with. It's perfectly acceptable to simply say that you are not happy with the results. You don't have to rant and rave or ask for your money back but certainly the person who has done the work needs to know clearly that the outcome is not what you expected. Otherwise they will go along assuming they are doing an ok job when in fact they're not.
#28
Old 05-30-2013, 08:51 AM
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I found a service that will hand-match paint. I was thinking about having this done and supplying the paint myself so there's not another screw-up when I get my signs repainted. How much does a pint cover, and do I need to also buy clear-coat, or is that just for cars or a stock item for any color? Does automotive paint go bad once it's open or is it like house paint where it will be good for years if you stir it up?
#29
Old 05-30-2013, 08:54 AM
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So, the OP rejected the paint because of how it looked in the can. How did it look when applied to the surface?
#30
Old 06-06-2013, 06:59 PM
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I didn't reject the paint based on the way it was in the can. The finished job was way off.

Anyway, I found a service that guarantees they can get the paint the correct color by hand matching. I was thinking about buying paint from them and then finding someone locally to do the actual painting. Do I have to order clearcoat at the same time as basecoat, or will anything (like the guy I hire to paint it presumably has lying around) work. Or is clearcoat only for cars, and not antique signs.
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