Stonewash, opinions?

[benjamin2515101]

I've been wanting to try a stonewash finish, but I still have some questions. Is there any benefit to buying specialty abrasive media such as ceramic, or will small gravel from the home depot work? I will be
using a rolling tumbler.

I've seen some who etch first in ferric chloride, does this give the blade a gray color or?

What does a lubricant do, such as WD-40 or soapy water, other than cut down on the dust?

Any answers or discussion is greatly appreciated!

 

[Stacy E. Apelt - Bladesmith]

Read up on tumbling in general and most of that will get self-answered.

You need a liquid in the media to carry the swarf and small grit, ,as well as to cushion the abrasive.
You need a surfactant ( soap) to lower surface tension.
You need a de-foamer or it will make a HUGE amount of suds.
You need an abrasive that is harder than the object being tumbled.

Structured shape abrasives are better than gravel. (which might be barely harder than the steel)
The surfactant/de-foamer is available as a pre-made product.
Water is the usual lubricant/carrier.

 

[willydigger]

Disclaimer: I'm a novice and I've done 1 blade homemade. That is my experience.

I put stones in a bottle with some WD40 and shook it by hand for ten minutes. No pics of the bottle but think of a Nalgene water bottle. Plastic with a lid. I did not protect the blade or tip with anything. I resharpened when done.

I also used some PCB etch to darken first.

 

[Nathan the Machinist]

A lot of the stone wash finishes you see on knives are applied with big vibratory tumblers.

I've tried a lot of different media in attempts to save money over the "real" thing including gravel, pebbles, sand, BBs with abrasive grit etc. Pretty much everything not specifically design for the application did a poor job. I ended up using heavy aluminum oxide media, light ceramic media, and various polishing media like walnut shell loaded with rouge. (all for different applications).

You can run wet or dry, you'll get different effects. Wet gives more of a dark mat finish, dry more of a bright finish. Most people run wet because the media cuts better because it doesn't load up as bad. Dry has to be washed regularly.

The soaps and fluids have rust inhibitors and suspend the grit preventing it from depositing on your work in films that arrest cutting.

Something to be aware of is knife blades, when wet and in a vibratory tumbler, can seek each other out and stick to each other. When this happens one surface doesn't get cut and you get a bad finish. You can run a small screw and a nut through the tang to prevent this. Also, too many in at once can cause a log jam that can result in scrapping a lot of parts.

And lastly, the finish has to be pretty good before you start. The process doesn't correct or hide mistakes. Anything rougher than about a 400 grit will still be viable under the stone washed finish.

 

[JBS TOOLMAKER]

Not to get off topic, but I'm glad you pointed this out. I have seen several post where folks say this is a cover-up process. The smallest imperfection will show through on a tumbled finish.
To get a darker finish, I have been using a product called EVAPO-RUST. It's non-toxic ,biodegradeable doesn't burn your flesh and has detergent properties as well. I pour it directly in the tumbler. Works great on carbon steel, not too good on D-2 and stainless. Here is some A-2.