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Grit chart for compound/polish

I am one of those terrible people who washes his car about once per year. I figured it was time to give my 14 year old honda a buffing too. My question is about grit sizes of abrasive particles in compounds/polishes. I am an avid knife sharpenner and metal polisher, so have a wide assortment of aluminum oxide and silicon carbide abrasives. Ranging from 50 grit to 12.5 nano meters (yes you read that right, 1e-9 meters, as in 0.0125 microns). My question is about grits of abrasives in paint buffing compounds (yes i realize rpm difference and heat generation differences between metal and paint buffing). The specs i see for polishes call out grit of scratches they remove. I am curios to find out grit of abrasive particle in polishing or cutting compounds to get my bearings on which on my abrasives i should use. Feels silly to buy dedicated compound, since i already have pounds of abrasives or various grits.

Why not go to a junk yard and pick up a cheap hood or trunk lid to experiment with in does not have to be in good condition so you should be able to get a good price for one.

But these are NOT designed to polish paint. You WILL regret it if you try.

The carriers and grit for these products are specially designed for the MUCH softer paint rather than bare metal.

Go here…Home | Meguiar's Read up!

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The thing is: I am a nerd… I am one of those people that could spend a month learning about compound grit and carriers, oil, soap, water etc to then spend 1 day buffing the car once per year… The basic thing i am trying to determine for now is the actual micron rating of the compounds. Type of abrasive would be nice too, AlOx, crushed garnet, diamonds even… what is the standard stuff? I realize paint is soft, so putting diamonds in this list felt absurd…

I would try clay bar first.

THIS is the most comprehensive paint polish and care products site I know.

If you can’t fulfill your polish-nerd-vana here, it doesn’t exist!

Just wash the silly vehicle , use a name brand wax and see if that is good enough . People have tried buffing clear coat only to over do it and go right through to the paint .

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He’s not asking what to do, he’s asking where to find technical info on what’s in car polish. That could be hard to come by, see @Mustangman links.

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Thanks for the link. Looks like i’ve already watched some videos from them. I actually did about a week worth of youtube homework before posting this question. As mentioned above, i am looking for engineering level, rather than user level information. Normally, to remove scratches i used abrasives that are about 3 to 5 times smaller in grit than preceding step. With something as soft as paint I’d imagine 5x or may be even 10x would work. Which puts me in ballpark of 10K to 30K grit or about 1 to 0.5 micron But that still does not tell me the grit of what is actually used in compounds. Knowing that would validate my assumptions.

You might also research ‘color sanding’, which is used to remove paint imperfections like orange peel. Sanding goes through multiple grits, ending at around 12,000, then there’s a final application of a polish, but the bottles don’t indicate a grit size.

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Well in sandpaper, about the highest grit is 3000. Your knife sharpener may go up to 6000 or the leather belt. But forget about knife sharpening I finally bought a unit and sharpened my hunting knife I bought in 1957 with some success.

At any rate, using a 2-3000 grit wet or dry sandpaper would be only for a new finish or blending in overspray. Clay will just remove some surface impurities but should still be done first. Now Meguires products are a little easier to figure the grit, not by the numbers, but by looking at the red arrow that will give the grit as a relationship of the most course to the most fine.

At any rate then you would start with a rubbing compound to remove bad oxidation. Then use a finer polishing compound, then possibly the finest which would be a swirl remover. (Lots of choices in between) Then to seal or fill in imperfections you could use a glaze or not, followed by a sealer and/or wax. Rinse and repeat every 6 months. Usually, once I have gone over a new car with rubbing compound (or even 3000 grit) to flatten the surface, I usually can skip that step in following years and start with a heavy polishing compound instead. Might want to take a look at the Meg web site. Others may have a different routine but this has been my practice for 10-15 years or more.

My water stones go to 10K (1 mcron) and my compounds, whit i put on strops, go down to 125nm (nano meters) which is about 2,000,000 grit. Although i usually stop at 0.5 micron, so like 35K grit.

Correction: compounds go to 25nm which is absurd grit value. very rarely used.

I know who to call now. I never could figure out knife sharpening so I cheated and bought the Work Sharp.

Look at this video: How To Sharpen Knife - Near Perfect Sharpness from A to Z. - YouTube
That youtube channel has pretty good info on knife sharpening.
It all comes down to practice.
For the part relevant to this thread, it is all about grit pyramid. The order of abrasives. Start with coarse and progressively move to fine to remove the scratches. Too big of a jump will result in a very long time spent on finer grits to remove scratches from coarser grits. In case of paint it is not so noticeable, because clear coat is softer than steel, so material removal happens much faster. So, while overall process’s are similar, i lack the specific knowledge for car paint grit selection. I tried 0.03 micron alumina compound today and it seemed to work OK for final buff. May go down to 0.5 micron aluminum oxide for faster initial buff.

For regular work, yes. But for color sanding they can go up to 12,000:

But not often used, that’s true. More often in hobby work, like models.

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Spent many a year as a chef sharpening knives, and I am using One of these cheapo hand helds, and cause I cant seem to find a steel finish it on the unglazed bottom of some dishes. Mostly use a French knife, works fine for me.

The highest I’ve ever used on a car is 2000 by hand and then rubbing compound with a buffer.

@Barkydog You do not finish knives on a steel. The steel is used to realign the edge if it slightly bends. Most of the time, if the edge is properly sharpened it will never bend. The part that tends to bend is a weak concave edge from dual disk stones or the wire edge which was not properly stropped off after sharpening. Properly sharpening a knife on water stones up to 6K JIS grit (about 3 micron) is enough for all kitchen cutlery. A 1 micron is where the “scary sharp” territory starts. I usually take my knives up to 0.5 micron.

Also want to add is that there are several confusing grit scales… with microns being the common denominator between them.

Perhaps I do not know as much as you, Your explanation of a sharpening steel is bogus! The sharpening steel removes any burrs and hones the edge, be it ceramic or steel. Just basing my comments on a lifetime of experience and 25 years in the food and beverage industry, Site does not allow mp4, so a pic of a knife after cutting paper, sharp enough for me