Paint color matching for body repair

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pancho1984

New member
Don't know if this is the right forum, but...



can any of the experts here educate me on the various methods of mathing paint color when body work is done. I have an 03 Midnight Blue Honda that needs a new front bumper. The shop the insurance company sent me to stated that they use an imaging technique to derive the proper color. Are there other, and more importantly, or better methods to use?



FWIW, this shop was on the recommend list of D.C.'s Consumer Checkbook.



thanks in advance.
 
wahooB5 said:
Don't know if this is the right forum, but...



can any of the experts here educate me on the various methods of mathing paint color when body work is done. I have an 03 Midnight Blue Honda that needs a new front bumper. The shop the insurance company sent me to stated that they use an imaging technique to derive the proper color. Are there other, and more importantly, or better methods to use?



FWIW, this shop was on the recommend list of D.C.'s Consumer Checkbook.



thanks in advance.
Click to expand...



I actually do paint work and the paint code can be attained for your Honda by simply opening the drivers side door and looking on the pillar. It is very easy to find and once aquired can be used to factory match your paint. There are some shops that do use a special machine to determine the exact colour match to perfection but I don't see it very often. A proper match is very simple to achieve simply by using the factory paint code, matching the colour to the paint manufacturers paint book of variant shades and chooosing the proper match. Using a high quality paint is extremely important too - we use Standox and have never not been able to come up with a perfect match.
 
The device you're referring to is called a spectrophotometer, in layman's terms a paint scanner, and I have firsthand experience that they work very well.



A friend and I were repairing and repainting the fender of a classic Pontiac LeMans convertible a few years ago, and the car was scanned at the paint supplier via a portable spectrophotometer. They mixed the paint, and the shade (metallic) came out absolutely perfect when we sprayed it. They are very expensive devices ($10k to $20k), so you're fortunate your shop has one.



Like ShineShop said-not typical to see a shop with one. Best of luck. :)
 
OK at PPG in Europe this is the system that was implemented -

a 5 angle spectrophotomer was used to measure the paint colours, usually using the CIE Lab colour equation under D65 illuminant.

this "colour" was then matched to the closest available colour in the database

the nearest colour in the database was then corrected to give a match with original colour



NOTE : refinish paint and OEM paint is very different so every refinish formula has to be matched to every OEM colour. At PPG every attempt was logged in the database to help give the largest range of colour formulations available.

The theory on matching to a database and then correcting is that the software would only need to make a slight correction to a known formula therefore less prone to error.

A multiangle spectrophotometer is used as metallic and mica paints look different colours at different viewing angles. The multiangle spectrophotometer can quantify these differences to enable a better match.

To really be on the ball the match should be compared under different light sources to check for metamerism.



I will stop now



Steve
 
Well,please allow me to take the contrarian view.



Approximately 1 month after leaving the factory (nice new paint) two panels were repainted by the dealer - one on the car, one off the car. One was too dark, one was too light. The dealer assumedly used the "code from the door".



A year later, another panel was painted by an independent shop referred by my insurance company. Manager called me laughing, "come take a look. I don't think it matches". He called in the DuPont field rep, who brought the $20,000 color analyzer. Worse match than "from door". Sent a painted part to the DuPont factory to be read by their $50,000 analyzer. Even worse.



Brought the car to a shop that uses PPG, 99% sure that's the brand used at the factory. Mixed per the door, one tweak, not quite, second tweak, threw out the mix. Tried again, got it on the first tweak. Needed 3 coats rather than the two specified; direction of spray made a difference (left to right vs. right to left). Good match. They said they would save the actual mix code so that they could repeat it in the future.



Brought in two weeks later to redo the two original mismatches from the dealer. Couldn't hit it with the prior mix. Went through process again, finally matched it.



Observations, admittedly personal:

1. Use the same brand paint as the manufacturer. Even though the base chemistry may be different, the coloration at least has a baseline starting point.

2. Use a shop known for their colormatching expert. In my case, the automated equipment was worthless.

3. Check the color from different angles.

4. Check the color in different lighting conditions - sunlight, overcast, lightbulbs, flourescent. Look especially carefully if there was more than one tweak - chances increase that it will match under one or two conditions, but not others.

5. Check adjacent panels for directional consistency - I apparently do not have any metallic or pearl in my paint, but it's a "flip-flop". From one direction it's reflective and shiny; from the other, it's dull. Even though the color seems to match, adjacent panels may not (I would guess this would also happen in metallic paints in the particles are not equally distributed in adjacent panels).



That's been my experience.



BTW, I believe that the shop that could not get the match was recommended by Consumer Checkbook. If you want to post the name of the shop you're considering, I'll PM to you whether or not they're the one.
 
Refinish colourmatching is a mine field. A good sprayer though should be able to work with a paint though to help achieve the final colour. As Prowler said he had 3 coats put on instead of 2, spraying wetter or dryer will effect things such as "flip flop" esp. on metallic colours as will heavy or light application.

Prowler is absolutely right about looking under different light sources - this is METAMERISM - eg daylight and street light affect the visible wavelength of light emmitted by pigments ie match looks good under daylight but under street light, because different pigments have been used to the original formula, the visible wavelength of light changes to give a different colour.

In my experience the refinish people find it easier to match OEM colours than vice versa. This is because the pigment choice in OEM is more limited - when stylings were carried out using refinish "new" colours it was very difficult to get close with an OEM paint formulation (film thickness is also very different).



Anyone noticed the colour difference on the Audi A6 bumper (fender ?) to body ??? I presume this is the same in the US as in Europe. Even if the same paint is used they always get this visual colour difference (worse in some colours (metallics) than others) due to the shape of the car and material difference between bumper and body.



Steve
 
Prowler just reread your post, as being a contrarian view well I would say more a realistic experience. A machine is good for a starting point, after that you need a good experienced colourer matcher. No machine I have ever seen is as good as your eyes, they are a very useful tool but should not be seen as the be all and end all.



Steve
 
Thanks, SP 325i, I appreciate your responses and learned from it.



As far as contrarianism, I guess there's three reasons:

1. Stir the pot (it's more fun that way)

2. Answers seemed too uniform, SOMEONE had to speak up

3. I KNOW what I experienced, I just didn't know why or what to call it.



Thanks for the education - I now know the explanation(s) for what I experienced.
 
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