I am touching up a few paint chips on my '88 420 SEL. Has anyone used enamel thinner to make the clear coat easier to apply? What mixing ratio did you use and how did you measure the thinner/clear coat to achieve the correct ratio? Thanks.

Thinner is only used with lacquer-based paints. Reducer is what you use with enamels. Reducer is used to bring the mixture to the proper viscosity - hard to measure with the small amount you're likely dealing with for paint chips. I would say just add enough to make the application "flow" and develop a gloss, but not too much. Too much and the paint won't stay in place. You need to strike a balance right in between. This is where experience or, in your case, experimentation pays off. Get a piece of scrap metal or cardboard to test the viscosity of your mixture. Either way, to blend everything you will still probably have to wet sand and polish once it all dries out.

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86 W126 560SEL
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75 W114 280

Thanks for responding to my post. When I spoke to the folks at Langka they pointed out that thinners are of two types - lacquer-based vs. enamel based - and that an enamel based thinner should be mixed with the clearcoat. So I'm assuming that "reducer" is the precise term and that Langka used the term "thinner" rather liberally in their discussion. Is wet sanding/polishing always needed? I am a pure beginner so it sounds like something I should not be doing. In the past, I have had a difficult time working with the syrupy consistency of the clear coat so I was hoping that there would be a more user friendly approach. I'm a perfectionist but definitely not a paint repair expert. Your opinion is most appreciated. _ Hans

Reducer is certainly a thinner when that word is used as an adjective... Some jargons come about from accident and don't really make sense.. If you say Reduce when cooking you are making the liquid thicker...
Anyway, you need to find some good books ..... like the ones put out by Petersen Publishing Co on Automotive Painting...( I see them on Ebay for Cheap regularly) and really read them... over and over... also... find the best store in your area which sells Paint to Automotive Repair shops... tell them you are going to paint all your MB's... but that first you need to do this job at hand.. take notes when they are talking.. and find a single brand which has a ' system' ... paints /preps/ rubs/ .. which they know work together... and stick with them... read the instructions on each can and follow it... they have spent millions on R and D to get it right... don't take shortcuts... remember that you have to change the thinner if you are spraying at certain temperatures... and this includes your primer..
Yes, you have to use wet and dry to feather stuff out if you want it done right.. it is not hard... main rule NEVER TOUCH THE PAINT WITH SANDPAPER WHICH DOES NOT HAVE SOME KIND OF hard BACKING BEHIND IT... hard rubber squeegy, wood.. whatever.. never hands....
Painting can't be made user friendly... but the rewards of learning the rules and taking your time to do it right can't be matched by many other projects.
You need to learn how to use one of those drip buckets... it takes the guessing out of viscosity... ask the paint shop for one...
Also, take particular care to make sure you have sufficient air pressure...and that it is BONE dry... you need an air pressure guage on your waist before your lead to the paint can.. you look at it when you pull the trigger before starting to see if you are getting enough pressure at the can to spray... then proceed...

The folks at paintscratch.com recommend a 1:1 ratio of automative lacquer thinner and clearcoat for thinning the clearcoat. For small touch-ups just use an eye dropper for measuring equal amounts.

All the little touch-up bottles I've used were laquer based. Probably because they dry faster?

Anyway, here's some great touch-up info to peruse. Use info that seems useful. FWIW. http://www.unofficialbmw.com/repair_faqs/paint.html

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1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Thanks, those BMW pgs. are helpful. I have also learned that reducing a few drops of clearcoat with thinner does not work. The small amount of thinner evaporates too quickly so now I understand why the folks at Paintscratch were speaking in terms of reducing for spray painting (as in a large quantity mix). A few of the folks suggested skipping the clearcoat for touch-ups and i tend to agree b/c when I tried again to apply clearcoat out of the bottle it had the consistency of sticky maple syrup, a surefire way to ruin a nice paint touch-up job.