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Hand sanding a blade

This article was originally posted by Bruno[1]

The purpose of hand sanding is to bring a blade back to a near perfect finish, regardless of how badly damaged it was. Otherwise you might as well use a Dremel and sanding discs. Those sanding discs and drum wheels cost money, and if you have to remove bad pitting, you will spend a lot.

Contents

The ergonomics

Hand sanding a badly damage blade can take up 10 hours or more to do it right. Holding the sandpaper in your hand, or keeping it wrapped around something is a sure way to attract tendinitis. Been there, done that, found a better way.

The big part just fits in my hand, and I usually keep my index finger touching the thin part when I hold it. This way all tendons are in a relaxed state when I sand. The tip is wrapped with a strip of leather. This helps distribute the pressure evenly. The wood underneath it will have some irregularities that are visible otherwise when sanding with finer grits. If the sandpaper gets loaded with crud, I move the strip of paper a couple of mm and continue.

Types of sand paper and where to get them

A good place from which to get sand paper is an auto supply shop. The sand paper sold there is usually silicon carbide wet dry sandpaper. Grits carried are usually 220, 400, 600, 800, 1000, 1200 and 2000.

The price varies depending on the brand. 3M is rated as the best by the majority of SRP members, but it is expensive. There are cheaper brands that will get the job done. Most auto supply or body shops will carry other brands.

Regular woodworking sandpaper is Garnet, which, incidentally, is not good for metal.

Types of abrasives.jpg

The sanding itself

Let me tell about the difficult part: damage removal. This is the most tedious part of sanding, because if a blade is pitted, you have to take away a LOT of metal to remove the pitting, and you have to take away metal across the length of the blade, or you will end up with a blade that looks like some metal was scooped out of it.

Experience has taught me that the best way to remove pitting is by first sanding circular with a very low grit (80 - 120).

Circular sanding

Handsanding howto circular sanding.jpg

Circular sanding works quickest, and I think this is why: if you sand circular while going back and forth a bit, you are always sanding across (and NOT along) previous scratch lines. If you hit scratch lines from a different direction, they will come off much more easily than if you sand along the same direction continuously. Especially if there is a lot of pitting, you want metal removal to go as fast as possible.

Every now and again when the blade is completely scratched and satin looking, you sand back and forth along the blade until it is semi mirror shine. Even at high grits this is pretty easy, and you will quickly get an idea of where you're at.

Lengthwise sanding

Handsanding howto lengthwise sanding.jpg

Instead of circular sanding you could also speed up metal removal by sanding first from spine to edge, and then from heel to toe, and then from spine to edge again, but sanding from spine to edge is uncomfortable because the distance is so short. Note that if you sand in the spine - edge direction, you should NOT sand across the line where the spine hits the stone. For many razors this is obvious since the spine itself is nearly flat. However, some spines are wider. If you then sand all the way to the top of the spine, you erase the demarcation line between the blade and the spine. While this does not change the honing angle from a functional pov, you'll lose the crisp look of the spine.

As soon as all the damage is gone you are ready to go up in grit. Don't go up sooner because low grit is the fastest way to remove damage. Don't even think about sanding away left over pits with 400 grit paper, no matter how fed up you are with low grit sanding.

Progression of grits used

As soon as I am satisfied that the damage is gone, I use the following progression: 150 180 240 320 400 600 1000 1200 1500 2000.

At 240 I change my sanding method. From then onwards I will do 1 grit from edge to spine until all the previous scratch lines are gone. Then I go to the next grit and go from heel to toe until all previous scratch lines are gone.

If you removed all the pitting with the low grit, then from 400 onwards it takes very little time to progress.

By the time you hit 2000, the blade will be mirror shining, and ready for the Dremel, buffing wheel and polishing compound.

Hand sanding and polishing in action

In Praise of Hand Sanding Before Polishing

It might be interesting to graphically show the difference that careful sanding of a blade can make during restoration. To that I end we present a pair of buffed out blades. To keep the story interesting, there is a good blade which was rubbed over with lots of sandpaper before getting friendly with the polishing mops and a not-so-good blade which took the quick trip to the polisher in ‘as was’ condition.

[Note: The polishing work was done with a Creusen 6” polisher. It draws something like 500 watts of power and runs dependably and what is more important, fairly quietly. Of course, a polishing machine is useless without the extras, so we also have a fair amount in buffing wheels and polishing compounds. This process involves six different grades of polishing compounds which takes our steel from a dull sheen up to a mirror finish. Although it is a 6" polisher, the decision was taken to use buffing wheels and mops of 4" and 3" diameters. ‘nuff said and on with the info.]


References

  1. http://straightrazorplace.com/workshop/17007-handsanding-howto.html
  2. PaulX608 in http://straightrazorplace.com/workshop/35367-my-first-restoration.html

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