Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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Knifemaker / Craftsman / Service Provider
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I received an email asking about etching damascus. It asked how fine a grit to sand to. My normal response is "400 grit or finer". I though I would explain that in more detail here.
400 grit leaves fine scratches. They are acceptable for pre-HT is almost all cases, and post HT they are the minimum grit acceptable as a satin finish. However, with damascus, the final look will be defined by the etch. The etchant not only etches the different alloy content layers, ....it also etches any scratches in the finish. I have found that a TRUE 400 grit finish will etch OK most times. After the etch, clean up lightly with 320-400 grit again and then take up to 600-800 for a brighter contrast. That is the simplified and short answer.
The best answer to the question lies in how good your 400 grit sanding is.....and if it is fine enough. What I look for is seeing the damascus pattern in the sanded steel start showing up. This can happen at 400 grit in some cases, 800 in most cases, and 1000-2000 in a few rare cases. The point is that if you can't see the damascus pattern, you will often have to over-etch to develop the pattern, and then sand back for a proper look. The sanding back will affect the sharpness of the pattern, making places look muddy or weak. Often it takes several etch/sand cycles to get the whole blade good looking. Additionally, If the sanding isn't fine enough, there may be deep scratches in the damascus pattern that you swear weren't there before! There is no short cut here...if they are there before etch, they will be worse after etch....... sand them away before etching.
What I do is sand to 400 grit and look at the surface with a magnifier ( Optivisor). You can't get a good final finish on any blade without a magnifier hood IMHO. I like a #5 lens
Under magnification, you will see the 400 grit lines as very prominent scratches....and probably see the previous lower grit lines in there, too. Taking the sanding up to 600-800 will show haw really good/bad your lower grit scratch removal was. Usually, you see a few deep scratches still there at 600-800 that you didn't see at 400. Don't think that continuing on will take them out with a bit of elbow grease. Go back to 400 and get them all out before moving back up. I continue higher if needed until the damascus pattern is clearly visible. This is where I etch. I etch until my fingernail feels a sufficient "bite" as I run it across the damascus pattern. On some wide patter damascus, I go to a rather deep etch. On stainless and tightly twisted patterns, a much shallower etch works.
After etch and neutralizing, I go back one grit from where I quit and lightly hand sand with folder paper (3M colored papers) then again at the same grit or one grit higher as pre-etch. This is to brighten the whole surface. Then I switch to backing the paper with a hard felt block or a hard leather covered piece of wood. This brightens/polishes the high spots really shiny. Some guys use an aluminum or hard wood backer block. You only want to polish the high surfaces. This leaves a sparkling damascus look that does not rub off in the first use or two.
400 grit leaves fine scratches. They are acceptable for pre-HT is almost all cases, and post HT they are the minimum grit acceptable as a satin finish. However, with damascus, the final look will be defined by the etch. The etchant not only etches the different alloy content layers, ....it also etches any scratches in the finish. I have found that a TRUE 400 grit finish will etch OK most times. After the etch, clean up lightly with 320-400 grit again and then take up to 600-800 for a brighter contrast. That is the simplified and short answer.
The best answer to the question lies in how good your 400 grit sanding is.....and if it is fine enough. What I look for is seeing the damascus pattern in the sanded steel start showing up. This can happen at 400 grit in some cases, 800 in most cases, and 1000-2000 in a few rare cases. The point is that if you can't see the damascus pattern, you will often have to over-etch to develop the pattern, and then sand back for a proper look. The sanding back will affect the sharpness of the pattern, making places look muddy or weak. Often it takes several etch/sand cycles to get the whole blade good looking. Additionally, If the sanding isn't fine enough, there may be deep scratches in the damascus pattern that you swear weren't there before! There is no short cut here...if they are there before etch, they will be worse after etch....... sand them away before etching.
What I do is sand to 400 grit and look at the surface with a magnifier ( Optivisor). You can't get a good final finish on any blade without a magnifier hood IMHO. I like a #5 lens
Under magnification, you will see the 400 grit lines as very prominent scratches....and probably see the previous lower grit lines in there, too. Taking the sanding up to 600-800 will show haw really good/bad your lower grit scratch removal was. Usually, you see a few deep scratches still there at 600-800 that you didn't see at 400. Don't think that continuing on will take them out with a bit of elbow grease. Go back to 400 and get them all out before moving back up. I continue higher if needed until the damascus pattern is clearly visible. This is where I etch. I etch until my fingernail feels a sufficient "bite" as I run it across the damascus pattern. On some wide patter damascus, I go to a rather deep etch. On stainless and tightly twisted patterns, a much shallower etch works.
After etch and neutralizing, I go back one grit from where I quit and lightly hand sand with folder paper (3M colored papers) then again at the same grit or one grit higher as pre-etch. This is to brighten the whole surface. Then I switch to backing the paper with a hard felt block or a hard leather covered piece of wood. This brightens/polishes the high spots really shiny. Some guys use an aluminum or hard wood backer block. You only want to polish the high surfaces. This leaves a sparkling damascus look that does not rub off in the first use or two.
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