Thread: Abrasive progression question

Bill (or any other experts out there),
I was wondering if you might be able to help me out with the age old question of choosing the right tool for the job.
With regard to removing rust/pitting or simply bringing back a more or less stained/corroded razor from the brink, what is the progression of abrasives to use. Here is what I have so far:
sandpaper grit -- Micron size
150 -- 93
220 -- 60
320 -- 36
400 -- 23
600 -- 16
800 -- 12.6
1200 -- 9
1500 -- 8.4

The radial bristle disks Bill sells (and highly recommends) range in grit from 50, 80, 120, 400, and 'pumice'. When would you chose sandpaper over the bristle disk (or vise versa)?

Then there are the brown (coarse) and grey (fine) fiber wheels. Where are these used in the process? I know that during KornDog's recent restoration project he started with these. Are they typically used to take off active rust before proceeding to sandpaper in order to remove any pitting? Any idea what the equivalent 'grit' or micron abrasive size is on these so that I can put them on a relative scale?

Finally, I was recently on Keith's HandAmerican site and noticed that he has dry silicon carbide powders available in grits ranging from 100 on up to 1200 grit. Would there be any advantages/drawbacks to using dry silicon carbide in a slurry with some honing oil on a felt pad in a dremmel tool vs. PSA sanding disks vs. radial bristle disks?

I'm sure some (maybe all) of this is covered in your CD Bill. If so, please point me to the proper page rather than devulging all of your hard earned secrets--unfortunately the disk is at home and I'm at work right now so I can't search it. I just wanted to get some of these things straight in my mind before putting in an order for a bunch of abrasives that I may or may not need.

Thanks,
Ed

Hi Ed. While I'm not the expert, I have been doing quite a bit of research over the last day or two. Oddly, I was on Keith's site today too, looking for the PSA microfinishing film. I found it elsewhere in 1" discs though.

My experience with just two razors so far is that you can get pitting out with 60 micron, but it's a tedious process and works only for light pitting. I wish that I had one grit increment coarser on the razors I did. Bill's golden rule is to start with fine grits and get coarser until you find the sweet spot, then reverse the process.

Those radials are amazing. They seem so much gentler than their grit would indicate. Maybe because they are so flexible. I'm sure Bill knows why this is the case. 3M is a strange company. Their web site is worse than that of my local body shop. Also, it seems that the grits change colors depending on the disc size for some reason unknown to me.

What I found is that the fiber wheel grits are that of the Scotchbrite material from which they appear to be made. I don't think that 3M assigns grits to these, but I found a couple of sites that had the Gray at 320 and the Tan a 150. Others are: Brown=80 Maroon=220 white=600.

I hope this helps Ed. I'm sure you will get better answers from Bill et al, but I couldn't help throw in my two cents.

...rather than devulging all of your hard earned secrets

You can walk up to just about any custom knifemaker, and they will share just about anything they know. I have no trade secrets, and I am happy to share what I know with all of you. The reason I wrote the CD was because I was becoming swamped with email inquiries and couldn't keep up with them. Most of the questions were just about the same.

They all started out with, "I've got a quick question". Although the question may have been real quick, my responses to them sometimes took an hour or more. I got to the point where I no longer had the time to do that. That always bothered me because I have always considered myself to be approachable with these kind of things. I still get those emails. 10 last week... all quick questions... and all but three knew I had a CD out... but didn't have it yet. Two of the questions were not in the CD.

For many of the answers now, I just go to the CD myself and copy and paste the answer to the person in the email. These days, guys are wanting to know more, so I plan an update to the CD with much more info on it. Especially how to take out pins and tidbits like that. Maybe spring or summer.

Would there be any advantages/drawbacks to using dry silicon carbide in a slurry with some honing oil on a felt pad...

You know, you just threw on a light bub for me. I think I will try that myself. It actually sounds like a great idea. If it works, I'll give you credit for it in the CD update.

...what is the progression of abrasives to use.

As I stated in my CD ... use the least abrasive first. ALWAYS. After a little bit of practice, you can just look at a blade and determine what you need to do first. Heck, pretty soon, I'll just be able to defer all questions to Larry. I take pride in that... The last razor I sent him, though, will keep him coming back for more.

So, what is the least abrasive? That would be the radial discs (I don't think I have ever restored a razor without using one of these), then the pink flex polishing wheel. Then the fiber wheels. Generally, these are what I start out with on most eBay razors. Actually, that's a lie. I use a 2 by 72 inch scotch brite belt on my burr king. Since y'all probably won't be getting one of those, use the fiber wheels. Sandpaper is next. You have all the grits you need.

Hope that answered your question... for now, anyway.

That Burr King picture is pure porn!

So, if I have this straight, whenever possible I should work from the left side of this table because regardless of the relative 'grit' the radial disks will remove less material (are less abrasive) than the polishing wheel then the fiber wheels and sandpaper is the most agressive? If I have that right, assuming you are forced into using the sandpaper, you would then continue using the sandpaper through successively finer grits? Would you ever then move back into a less agressive abrasive e.g. a radial disk? If moving to a less agressive abrasive, would you then jump back up to a coarser grit?

I know I'm probably making this much more complicated than it actually is and I really need to just chuck a few of these things into my dremel and try them out for myself.

Does this table make sense? I really did not know where to put the pummice radial disk as the 3M web site did not give a grit or micron equivalent. Any thoughts? Additions? Modifications?

Can someone please tell me how to include a table directly in a post? Sorry for the pdf attachment. I'll fix it when I figure out how.
Ed

Adding dry abrasives to an oil base and then putting that on a felt wheel is something I have done. Guess what...it sprays all over the place!

If you want to make your own abrasives then purchase a "grease stick" ( beef fat/triglycerides), melt some in a double boiler and add in the dry abrasive(50/50). Let the mixture cool but continue to stir it while it cools to avoid settling. This "puck" of compound can then be applied to the felt wheel. Be sure not to use either a soft or "Rock-Diamond" hard felt wheel. I prefer the hard felt wheels.
www.durofelt.com is a good source for a sheet of felt.

Sandpaper has the highest density of abrasives per surface square inch. It therefore abrades the fastest. All else being equal of course.
www.caswellplating has products for making your own sandpaper devices. Both a glue and a liquid sandpaper. They have a ton of interesting stuff.

Hope this helps,

...I really need to just chuck a few of these things into my dremel and try them out for myself.

Hello

Ed...

Like anything we do, we have to learn what happens with what. You just have to practice. Use old blades to see what the tools do to the surfaces. This is one of those things that cannot be followed with a chart or rules... except... use the least abrasive approach first. Like Larry said, once you have determined how coarse you need to get, then it's back through every one of the progressive grits to get smooth again.

You can switch between "families" of abrasives to get the effect you want. Your chart is arranged by the numbers, but unforunately, it won't work. There is a big difference, for instance, between 400 grit sandpaper and 400 grit radial bristle discs. Use the combinations of tools that work best for you. You do not have to use all the abrasives in every group every time.

If a blade only has tarnish, use the felt wheels or chamois cloth wheels and a polishing agent like Flitz, Maas, or Fabuluster in a stick. Randy has some good info there.

Adding dry abrasives to an oil base and then putting that on a felt wheel is something I have done. Guess what...it sprays all over the place!

I have avoided this same effect with pastes by not applying it directly to the wheel. I smear a little on the blade directly and then use the polishing wheels over the applied paste. Not quite as messy.

If the blade has active rust/oxidation, then you need abrasives. Sometimes the radials work and sometimes I will just go with a fiber wheel. Another trick... Let's say you ran a fiber wheel and the finish is too rough. Then go to a polish phase. That will dilute the parallel marks. Then go back to a radial for a finish. Not a single one. You would have to have at least three on a single mandrel to get a good effect. Like I said, practice, and use what works best for you.

If the blade has pitting... and you want to eliminate it, go straight to the sandpaper. Deeper the pits, the rougher the grit.