Hand vs Machine finish, a question in two parts.

[mgysgthath]

For non damascus knives, is there any tangible benefit to a lengthwise hand finish vs a belt finish, or is it purely for aesthetic reasons?

For damascus blades, and the main reason I'm asking, is there a tangible downside to the quality of the pattern/etch due to the belt finish?

I've had several people here and elsewhere recommend hand sanding my damascus, which I'm okay with but I'd like to know the reasoning behind it. If for example I've got my blade at 400 belt finished, and kept going to 650, 1500, 3000 etc, would the etch be worse than if I stopped and hand sanded (direction irregardless) from 400 on up? All things being equal, assuming all the previous grit scratches are gone etc, I just want to turn out the best knife I can. Personally I prefer a machine finish as far as eye appeal, but I'm fine with hand sanding if it makes a difference in damascus.

Hopefully I made sense and didn't ramble too much, fairly tired at the moment. I searched and read through a lot of old posts about hand sanding but couldn't really find the answer I was looking for.

Thanks all.

 

[Darrin Sanders]

If the finish is smooth, even, and flat the direction of the scratches should make no difference after etching.

 

[Mike Davis]

The reason for a nice, even hand sanded finish for damascus is that when you etch after a belt finish, it will amplify the scratches. You will see them in the damascus as opposed to a nice smooth finish on the damascus. I take them all to an A30 belt finish, then hand sand up to 600 grit. Going higher than 600 grit is not necessary, and can actually hamper the etching process.

 

[mgysgthath]

I was talking to Ed C. last night just before I posted that, and that is partly why I asked this specific question. He suggested 800 grit, sometimes 1200 grit, and not to belt finish it but hand sand it. I was under the impression that as long as you are sure all the scratches are gone from previous grits that it would look alright? The pictures from my 15n20/1080 WIP thread are 400 belt finish, and I don't see much in the way of scratches there, although I didn't etch long so that might be why.

Thank you guys for the advice (and Ed), any information is good information. I have nothing against hand sanding except I have no hand sanding paper except handle finishing wet paper in 1000-1500-2500 grits, so I'd have to order some if that seems like what I should do. I do prefer the look and "ease" of the machine finish, but I'd like the damascus to look as good as it can. Not so much for my first billet of 36 layers but once I get my press built and start doing 300+ layer twists and raindrops and mosaics and stuff, then it will be a lot more important.

 

[james terrio]

I cannot comment on finishing damascus, having never worked with it. I will say that I personally prefer a high-grit (2000 looks pretty sweet to my eye) hand-rubbed finish, but there's nothing wrong with a coarser hand finish, or a machine finish if it's done well. Sometimes that's just what the client likes, sometimes it's a budget thing or depends on what tools you have available.

I was under the impression that as long as you are sure all the scratches are gone from previous grits that it would look alright?

That's true. The problem is, with a typical machine finish it's very hard to tell if all the previous, deeper scratches are really gone, because they all run the same way. If your grinding skills are good, you can go straight from roughing in on a 50, shine it up with a 400, and at first glance it will look pretty decent. (This essentially how most factory knives are finished.) But a few swipes lengthwise will almost always show a heckuva lotta deep scratches. It's the same reason hand-sanding gurus advise to change directions between grits.

You don't really need to continue handsanding until those are gone, you can just go back over it a few passes with your final grit belt, and check it again. When your pleased with the uniformity of your scratch pattern, a couple cleanup passes with a clean, fresh belt of your choice will be all you need for a nice, smooth "machine satin" finish. It really does make a difference in the final result, and it isn't that much more work.

 

[jdm61]

I have a buddy in Belgium who now finishes all of his blades the same way now, be they straight steel or damascus. He goes up to 400 grit on the KMG, then goes to the buffer. One side has a fine Scotch Brite flap wheel and the other size a muslin wheel. He goes from the Scotch Brite to the wheel loaded with white compound and he is done.

 

[mgysgthath]

I suppose I could always just finish it on the belt and see how it etches, and if i see lots of scratches just go back and hand sand it. I already have the belts so I'm not out anything to try, and 400-3000 grit belts aren't going to remove much metal so I'm not worried about that. I do have a scotch brite belt actually, but I'm not sure what "grit" it is, I've never used it as I haven't tried a satin finish yet which is what I think it was suggested for. I don't have a buffer so I can't really buff it, unless I use my cork belt with compound. I guess I will experiment and see what happens, I just didn't want to ruin my first damascus blade ever. Thanks for the advice everyone, I'll update my WIP when I get somewhere (waiting on things to arrive in the mail in a couple weeks).