Tips on "Cut and Buff"

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Tips on "Cut and Buff"

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Factory robots are programmed to apply paint on today's cars. Some robots apply paint very well and the final finish is bright and shinny. I have seen factory paint jobs that weren't very good. While shinny, the topcoat of clear contains way too much orange peel. As far as I know, there may be only a few elite car manufacturers that go the extra mile to perfect the clear coat on their vehicles. For the DIYer or for a custom paint shop hired to paint your car, "cut and buff" refers to perfecting the clear coat making your car's finish look like glass, or reflect like a mirror. If you attempt to "cut and buff" yourself you'll find that it is not only time consuming but requires meticulous attention to detail. Most importantly, there must be a good foundation of clear on the base coat so that the clear is thick enough to remove painting imperfections (orange peel, for example) through the sanding and the compounding/buffing process. If the clear is too thin to begin with, one runs the risk of removing too much clear and creating a "light halo spot" or even worse, breaking through the clear into the base coat. Below are some tips being presented based on my personal experience.

1. Decide early on that your clear coat will be subjected to sanding and compounding.
2. If you are shooting clear, apply enough coats of clear to ensure you have a good foundation of clear to sand.
3. Prepare to perform the "cut and buff" procedures by getting the right grit sandpapers and sanding blocks, hard and soft. WetorDry 3M is good stuff.
4. Decide in advance how you plan on compounding the clear coat following the "cut" procedure. Know what buffing/polishing tools you will be using with the appropriate sized compound and buffing pads.
5. Evaluate the condition of the clear coat by looking at imperfections and dirt in the clear.
6. Choose a flat area, 12" x 12" to sand using 1000 grit wet and a hard block. Use a bucket of clean water and spray bottle of Windex or Glass Plus without ammonia to lubricate the surface and the sandpaper. Also have a wet microfiber towel to remove sanding sludge away from the surface.
7. After working the test area with 1000, move up to 1500 and re-sand the area. Wipe clean. Look for consistency in the sanding. While wet, use a hard block 3M squeegee and draw it over the wet area drawing the water away from the surface and collected into your microfiber towel. If there are speckles of bright clear exposed after drawing the squeegee across the surface, more sanding is required. It could be removed with 1000, or 1500 grit, your choice. Once the test surface is dull in appearance, break out the compound and polisher. Test compounding this area. The compounding should polish the surface while removing some of the scratch marks from the sanding. 1000 grit is fine, 1500 is finer and removes 1000 grit scratches. 2000 grit removes 1500 and 2500 removes 2000. A good compound and buffing compound should not only remove the finest scratches it should provide some shine to the surface. Polish is the final step.
8. Ensure that you don't skimp on using fresh wet or dry sandpaper. It wears out and 1000 can easily become a weak and inconsistent 1500. Fresh paper that is cleaned often in a bucket of clean water will help remove sludge particles and prevent the clear coat from being deeply scratched. If a big scratch is noticed, this can be fixed by moving up to the next grit of paper and compounding it out.
9. Once the 12" x 12" test section is give the full treatment to include polishing. You will be able to see what grit paper you need to start with to do the remaining surfaces of the car. It will give you a way to judge how much time you will need to get a first class mirror-like finish.
10. Be patient. If you tire, take a break because concentration is needed especially on edges and curves. Remember, don't be too aggressive with the sandpaper or with the buffing machine. If you are too tire to keep thinking about what you are doing, you are likely to make a mistake. Do not make mistakes. Take a break often.

I'll post photos of some of the tools and products I've used on my 79 TA.
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Re: Tips on "Cut and Buff"

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The first photo shows the various blocks used to sand (the cutting process) the clear coat with 1000, 1500, and 2000 grit 3M Wetordry sand paper. (Missing is the 2500 grit packet of sandpaper I also used.) The photo also shows the compound and polish used to buff out the clear after it was successfully wet sanded with the aforementioned grits.

The middle photo is a closer look of the sand paper and the two different size squeegees used to draw across the wetted surface to clean it and see if there were any shinny spots that needed attention with a little more wet sanding. The surface must appear flat (dull), no shine to it before compounding.

The bottom photo shows the compound (Cutmax) and the polish (Ex 04-06) used with Hex Logic foam pads (Chemical Guys products). Sonax is a German product. The Cutmax stays wet for a long time (doesn't dry out quickly requiring a spritz of water to keep the compound wet and working) and removes 1000 grit swirls easily using a orange (med cut Hex Logic pad). The EX 04-06 is a polish and will remove swirls caused by fine 2000 and 2500 grit sand paper. I have used a white Hex Logic foam pad and the polish to get a nice shine. The car has yet to get it's final buffing with an ultra-fine red Hex Logic pad--someday, when the car is detailed for a car show. ;)

Colorsanding1.jpg
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Dirt in my clear coat! Another tip.

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Dirt gets into wet clear coat because it does. --Winston Churchill

Okay, you got me. Winston Churchill never said it because, well, clear didn't exist when he was alive. Socrates would have said it too. It's a fact of life even if you have access to a very expensive down draft spray booth. If you're like me, and gamble to apply clear on top of a new color, and you're shooting at home in a garage or shop, you will get dust and other floating dirt into your clear coat--probably more than you'd get in a down draft spray booth. Consider the crap in your paint as imperfections, not flaws. A flaw in your paint might be a run, or a fish eye or solvent pop, or pin hole. (Some consider orange peel to be unacceptable and a paint flaw --as I do.) All of these "flaws" can be fixed by allowing the clear to cure and attending to the flaw by sanding the area and re-coating the area with more clear. This should be done the same day of applying clear or within, let's say 24 hours. Check your painting literature on re-coating clear.

Dirt, can be largely corrected with the "cut and buff" procedures. Orange peel--can also be remedied to a large extent with "cut and buff" as well. Sometimes, while wet sanding, a small pin hole may be detected. The pin hole could be a flaw like "solvent pop" but could simply be a piece of dirt that was dislodged during the sanding leaving a tiny pin sized hole in the clear. If something like that happens, more sanding of the clear may make the hole disappear especially if it's not too deep. Check the depth of the hole. If it is deep, the quick remedy is to apply a pin hole size drip of mixed clear into the hole, let it cure and sand the area with 2500 or higher wet sandpaper; then machine buff with compound.
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2500 Wetordry Sandpaper: Mirror Shine

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For a daily driver, 1500 Wetordry Sandpaper used wet, will eliminate most dirt and imperfections allowing a good compounding with a machine to remove most sandpaper scratch marks. The shine will be deep and with a good polishing and waxing will look great. Going the extra step to 2000 and then to 2500 will improve the clarity of the surface and provide that mirror shine.

On my Trans Am, as mentioned in other posts, I've gone the full distance and the Nocturne Blue with clear cut and buffed with 2500 looks terrific. The paint job that I did is not flawless, I have to admit that, but it is first rate overall. The extra time spent massaging the clear made all the difference, in my opinion.

I'll give an example on how the hood was done.

After shooting clear, I tried 1000 grit (wet) first and saw that it wasn't needed to remove dust and minor orange peel. So, I went up to 1500 grit (wet) and that got rid of the dust and 90 percent of the orange peel. To see what the end product looked like, I used an orange Hex Logic foam pad and Sonax compound (see photo above) and worked the area using a few different speeds. Before going to the next speed, a microfiber towel was used to wipe off the compound residue and that exposed a certain amount of shine. More buffing was done with a slightly higher speed and that too was wiped off exposing more shine. I looked to see how the compound was removing the 1500 grit scratches. It was doing a good job. A third buffing began at a higher buffing speed and worked into the paint. This was wiped off and more shine was revealed and 95 percent of the 1500 scratches were gone. In my opinion, this sheen and paint perfection was good for any car. However, my goal was to polish it up like a jewel. I could get it better and realized that 2000 would be tried and my process was the same with the 2000. When done, the paint was exceptionally clear and it was very hard to pick up swirl marks or any kind of 2000 grit scratches. The entire car received this treatment.

The car sat for months in this condition before I stepped up to 2500 Wetordry sandpaper. This would be my final effort. Now, keep in mind the paint had a brilliant shine sitting in the garage. To the casual observer (noisy neighbors)(my wife) the car looked done. I showed the car to some of them and they voiced their astonishment on how good it looked. (But I wasn't done, I could squeeze out more depth and clarity with 2500.)

Then it was finally time to begin dulling that sparkling finish with 2500 grit (wet) sandpaper. Small areas were worked, cleaned off and buffing with compound and a fresh orange Hex Logic pad began. Three different speeds and wipes in between each higher speed proved to provide a deeper clearer shine. My process was at hobby speed, not commercial custom shop speed.

In theory, the entire car could have been sanded with 1500, then 2000, and then 2500 before any compounding was done, but my personal hands on inexperience with the Axalta clear caused me to be cautious. Lack of hands on experience and being cautious made me go s-l-o-w.

The TA has a deep mirror shine and is protected with Mequiars gold wax. 8-)
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