Hi folks, new member here. I recently repainted (base + clear) a portion of the door on my truck. This was done in the ubiquitous Ford "YZ" white. The results, given my experience level, were great - better than expected really and the final white color was a close match.

After about 3 weeks time, I went out and used a 3M cutting compound and rotary buffer to remove a few dust nibs and flatten out the surface a little. This also worked great - I thought I was done. But a few days later, I went out and the area I buffed had turned yellow. Uggg.. start over.

I decided to sand and re-paint the area, and would again like to cut and buff. But before I do, does anyone know how a white paint could have been turned yellow by buffing? Did I use the wrong compound? Did I buff too much? Can a heat build-up issue cause this? Any observations appreciated! - Thanks

Need more information and some pics if possible.

What materials did you use?

What color did you paint over?

How many coats of clear?

Which 3M compound?

How did you go about the cut and buff process?

Thanks for the reply Coronet.

'68 Coronet R/T wrote:Need more information and some pics if possible.

What materials did you use? - Purchased online. Not expensive. See attached pic.

What color did you paint over? - Typical light grey automotive primer (rattle can).

How many coats of clear? - 4 coats

Which 3M compound? - 3M Heavy Cutting. (For "gelcoat" .. hmmmm). See attached pic.

How did you go about the cut and buff process? - Rotary buffer using soft cotton pad. See attached pic. Took it slow and easy, as is advised.

I'm sorry I don't have any pics of the yellowed panel.. I've already repainted it.

Of note: I painted 2 sections at the exact same time. One I cut and buffed, the other I left alone. Only the section I buffed turned yellow - the other one is still perfect.

Also, I noticed that after I decided to repaint, as I removed the yellowed color, the bright clean white underneath was revealed - definitely somehting seemed to have gotten into the top layer of clear.

Now that I'm looking at the 3M product, I see it is labeled for "gelcoat". Now I'm wondering if this should not be used on paint or clearcoat and is the source of my trouble..? Come to think of it, that bottle is probably over 10 years old. Uggg

If you were using a product like that which is designed to "buff" a gelcoated or industrial surfaces I can guarantee you it was too rough for your surface. More than likely you overheated the surface driving some of the old unstable solvents in that compound into the surface of the paint. If you go back and look through some of our old threads in this section you will see different levels of the Meguiars compounds which are safe for modern clear coats.

Thanks Darrel. I don't have much experience with this - I'm learning from these experiences. BTW the re-paint looks great. I'll use Meguiars on it.