tiny scratches

[tpeart]

im just starting out can anyone help me out with this i just finished polishing and buffing a piece on a s.s gas tank it looks great but up close i can see tiny little scratches in the finish i tried differnt wheels and compounds but i just cant seem to get them out any ideas to get them out thanks

[pickleboy]

i have gotten some great finishes on stainless lately but the micro scratches are still there. i have never been able to get the "perfect job". as with most polishers here we find that the customers are very happy with the finish even if we are not. all this to say that you may never get all those suckers out of the finish.

[thesound]

I've been toying with the idea of buying a whole case of microfiber towels, cutting 8" or 10" circles out of each, and then taking them to a sewing shop and having them sew them all together to make buffing wheels out of them. I have a theory that these mysterious tiny scratches are the results of the threads in the buff whipping the surface of the part. (Probably most likely during the spiral sewn stage but the loose cotton/white combo doesn't have enough cutting action to wipe them out.)

I think the "solution" lies in decreasing the thread width in the buff to a small enough size that the human eye cannot see the scratch pattern. Maybe microfibers are the answer?

[thesound]

Here's an excerpt from an article I found that deals with how to achieve different grades of finishes on the #1-#8 scale:

"Because stainless steel is harder than aluminum, you will need to make allowances from the known methods for stainless steel when working with aluminum. The stainless designations are as follows: A #3 finish is generally produced using a 120 - 150-grit sanding belt. A #4 finish is produced using a 180 - 220-grit sanding belt. A #7 finish is a beautiful mirror but with pronounced grain lines, while a #8 finish is generally regarded as a mirror with no grain lines. In the United States, a #8 mirror may still have very light buff lines. A #8 finish from Asia will be 100 percent free of all lines. This Asian #8 is extremely difficult to duplicate or blend to because the final process is different from conventional buffing, thereby leaving no evidence of having been buffed."

http://72.14.203.104/search?q=cache:...s&ct=clnk&cd=2

The author neglects to mention the "final process" that aluminum needs to have done to it to get an Asian #8 finish. Hmm, international trade secret perhaps?

[tpeart]

it seems like its the wheels making the little scratches could that be it i used a spiral and a loose sewn i played around pressure and speeds oh the wheels were on an adjustable speed angle grinder i heard of using some polish and fine steel wool do u think that could help

[thesound]

Originally Posted by tpeartit

seems like its the wheels making the little scratches could that be it i used a spiral and a loose sewn i played around pressure and speeds oh the wheels were on an adjustable speed angle grinder i heard of using some polish and fine steel wool do u think that could help

Wouldn't hurt to try, because if it ends up scratching the surface more it can always just be buffed again. Honestly though, if that were all that was necessary I think #8 grade finishes would be the rule rather than the exception.

I'll admit that even the microfiber buff idea is probably going to have marginal results, and any improvement that it might make is going to require that the sanding stage of the process be extended from a 600 grit finish to more like a 2,000 grit finish. Just a hunch, but I don't see a microfiber cloth having enough grunt to wipe out 600 grit scratches with emery, but I could be wrong.

In all honestly, I think the "final process" that that article is talking about to get the Asian #8 finish involves India Ink. I've played with India Ink briefly, and it is extremely sensitive to friction. Any high speed rotational tool is out of the question with this stuff because the air given off by the wheel and the friction produced causes it to dry in a matter of seconds. The impressions that I came away with from the little amount of experimentation I did with it are: any complex shapes will necessitate that the ink be applied by hand to cut down on friction losses,(unless you have a multi-axis CNC machine at your disposal), and whatever "device" being used in place of a buff must be both smooth, flexible, and somewhat solid. I believe the conditions for applying the ink are going to have to be good enough that the ink can constantly be refreshed with moisture during the working phase AND whatever substrate being utilized to work the ink into the surface of the part can in no way leave any type of footprint of it's own. Without some type of purpose-built equipment designed to accomodate these conditions, the process will be next to impossible to achieve any noticeable improvements over standard buffing methods.

Just my $.02

[mpierich]

Just wanted to point out that the phantom scratches I always see are almost certainly interference patterns from even smaller scratches. I know this has to be true because they go in directions I never did, like in a circular pattern. When I hold a strong light against the piece, I don't see directional scratches...I see circles, which I certainly didn't induce directly. Not sure how that helps, but there you have it.

On the Asian finish and the India ink...if you had 10 Asians working by hand for 25 cents an hour with microfiber cloths and some ink, maybe you'd be getting those results too, lol. Seriously, maybe it's a super low-speed but more lengthy process than we are willing to undertake.

I'm glad this has come out in the open in the past year. Pretending we consistently get "perfect" results doesn't help anybody.

[thesound]

Aha, I think I may have found something. Check out what this says:

Rubbing out by hand
The final step is to eliminate all traces of buff marks - leaving only a perfectly clear liquid black finish. This is easily accomplished by making a one-inch, six layers deep square of high quality facial tissue and putting a dab of three- or one-micron diamond on it. Then dampen it slightly with denatured alcohol and very gently rub the surface in two-inch strokes or less, exactly as if you were waxing a fine vintage car.

Don't give in to temptation and press harder to get out certain buff marks and don't use strokes longer than two inches or scratching the surface becomes a real possibility. You might be forced to press down harder in some areas, but do so reluctantly, as a few extra minutes rubbing by hand is faster than going all the way back to a hard buff to get out a mean scratch. It also is helpful for you to be in as clean a room as possible when buffing, as grit constantly falls from the air in most shops and loves to put deep scratches in optically polished surfaces. Also be sure that your light fixtures are clean before buffing, as this one source accounts for more than half of all dust contamination.

Once hand rubbing is complete, wash off everything with more denatured alcohol and soft tissue.

http://72.14.203.104/search?q=cache:...s&ct=clnk&cd=1

Diamond paste is pricey, but worth a shot. I think I'm gonna try this out myself.

[mpierich]

Originally Posted by thesound

Aha, I think I may have found something. Check out what this says: ...<snip>...

Diamond paste is pricey, but worth a shot. I think I'm gonna try this out myself.

Go for it! I'll chip in a bit to help pay for the diamond paste if you want. I was thinking a final hand rub, but have no idea what to use. Maybe this is it.

Anyhow got to be easier than messing with India Ink, lol...

[tpeart]

ya i was thinking of doing something along the same lines but using some kind of metal polish and maybe some white compound ground down to a fine power kinda form then using a foan or some sort of very soft wheel and trying that as a final buff we will see if it works i guess thanks for all the tips and help too guys i really apperetiate(spelling) it