when is a knife finished

[chichi]

Most knives are finished to a smooth, bright shine. This is usually done by using proressively finer grits of abrasives. A finely finished knife is considered a mark of good workmanship.
A minority of makers just grind and shine the bevel and leave the hammer marks and even forge scale on the blade.I believe Japanese blades are sometimes left in an "unfinished " state.
A lot of people seem to like this rough look. I am wondering if there is a large difference in the soundness of these two types of blades. Putting appearance aside, does a totally smooth 400+grit polished blade perform substantially different from a blade with a well ground bevel and honed edge that has hammer dings or some forge scale remaining?
Has anyone actually tested for differences?
Thanks for your comments.

[Steve Sells]

Generally, the smoother the finish the less rust will be able to attack it, as for cutting I do not have any testing proofs. My experience says with all other factors being the same they should also cut the same, in most cases.

But I admit I feel a fillet knife with forge finish may be a problem, so I am sure there are other things I am not considering. I would like to see some testing data on various finish types effects, not just high finish vs. no-finish.

[felix24]

yeah it will not rust as easily if it's well pollished.
i don't have any evidence to back this up, so someone give me a virtual slap if i'm wrong, but i'm guessing it will also cut better if the bevel is polished up because there will be less friction between the blade and the object being cut. it's probably only a minor difference if any at all.

[Rich Hale]

I believe the answer to this lies somewhere in between personal preference, desire, ability, equipment and experience. I like a mirro polished blade, It toook me a while lto be able to do tha and tat is wot I make for all fixed blades, Ok maybe for a one off now and then I do a satin finish. Folding knives are hand rubbed satin finish as I like that look. Hammer marks on a blade are scars in my eyes. However there are some folks that make that an art form. Research Danial Winkler for examples. To forge a blade and finish to your preference is really wot matters. Decide wot works for you and go for it! later on i f you wish to change do that also.

[BIGGUNDOCTOR]

Some may like the forge marks to show that it was handmade, as opposed to pumped out in some factory. I like knives that are not real flashy, as they are just tools to me.

Now for specific functions a mirror polish is required sometimes. like knives used to cut rubber. Some kitchen knives have vertical grinds to break the tension allowing items to drop free, and not stick to the side of the knife. Polishing will help seal the blade by smearing the metal, and closing the pores on the surface. When bluing a gun we didn't go much beyond 230 grit, or power buffed as this resulted in a shorter life on the finish. The less than mirror finish allowed the bluing to bite into the steel resulting in a deeper finish.

I would believe that a smooth finish would be stronger, and resist cracking sooner than a rough blade of the same design. Polishing will remove the small stress risers formed from forging. Any place with a sharp edge, or small knick is where it will crack when stressed.

[chichi]

Thanks for all of the good comments. I like the rough look, but years ago finished at a bright shine. I have a square wheel grinder so that is no big deal. But , grinding and the dust caused me to lose interest in shiny so I now prefer rough.

[hellbilly]

I'm a newb !! when making my knives i have always sanded them smooth & bright shiny.But After heat treating this knife I coudnt sand & polish it ! I liked the dirty old look of it ! So I guess its finished !!