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Polishing Inside Corners

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Hello everyone,

I am fairly new to tosogu and currently working on a tsuba. Part of the design calls for carving out some of the background, and I am practicing polishing a smooth slope and its transition with the foreground features.


As you can tell, the closer I get to a border or to a tight corner, the more I am struggling, and I am looking for advice on how to effectively cleanup and polish close to details that need to be preserved. The tight inside corners are particularly challenging. I do have small stones, but nothing that small. A small piece of sandpaper wrapped around a toothbrush just about gets in there, but lasts about 2 seconds and I'm thinking there has got to be a better way :P or is there?

I have read Jim Kelso's turorial on file and stone finishing, and that has been helpful in dealing with larger areas (thank you Jim!). I can see how I could eventually get the surface next to those details cleaned up with just a bit more patience, which I'm more than willing to exercise, but I'm doubtful that I can effectively deal with the tight inside corners that I'm currently struggling to even reach.

Hopefully someone can point at an element of answer, thank you!

Edited by Francis Gastellu
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Well, I managed to shape a couple stones to a tight point, and I made myself a needle shaped burnisher. Combined with the careful hand use of gravers as scrapers, and more patience, I got to a better finish in the inside corner.


There are still issues here obviously (background flatness, and the rounding of the foreground due to my indiscriminate use of sandpaper without hard backing), but I was focusing on the tight corner and that's a lot closer to what I want (this is just a practice piece).

Additional tips are still welcome :)

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Hello Francis,

I am pleased to see your pursuit for solutions to the problems that moving forward presents.  

Occasionally Jim Kelso does post quick videos of technique on his Instagram page.  Forgive me if you already follow him there, but here is the link to his account:  https://www.instagram.com/jim_kelso/

I face such tight corners with wood and with clay.  Each material provides its own challenges to such situations.  Wood has a grain that must be respected and understood when cutting or shaving so using left and right edged versions of certain tools can be very helpful.  Clay is easy, one just needs to be gentle and make sure the edges are straight, or curved as needed, and sharp (I use bamboo).  

I wonder if an alternate approach for the metal could be a straight edge and scraping.  I simply do not know about metal carving, though I love watching Jim's gentle persuasions with it.


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Thank you Janel for your reply!

I have been an avid follower of Jim Kelso on the web but did not realize he had more of his work on Instagram, thank you for this!

I think you are right that scrapers are at least a part of the answer here, and I'm right now looking at different geometries for this specific job. When it comes to polishing to a finish though, I think there is (at least for me) a bit of a gap between that and being able to move on to powdered abrasives. I've been somewhat able to bridge the two with shaped stones and toothpicks wrapped in sandpaper, and I am still experimenting with other options.

For instance, I've had some measure of success with a custom 1/16 rod sharpened to a point, with just one facet:


This acts as very mild bur as well as a burnisher of sorts. It needs to be used with the lightest of touches, and still doesn't quite leave a smooth finish, but it's been helping me get the floor of those corners flat, leaving a texture that's not as hard to deal with as what was there before, if that makes sense. I use this after scraping, and before stones/sandpaper/powder. 

I got started on the actual project, and this is where I'm at (silver inlay on shibuichi):


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Francis ,welcome, I mostly do wood carving , and I use a homemade tool to polish. Mine is a string and you can just use the edge to reach the hard to get. The other is chamois , a soft leather. I cut it in strips and attached to a sanding drum . The nylon string was untwisted and attached to the drum. These are Dremel tools. Or you can use a threaded with 2 nuts and washers for a drill . Using high speed let the string hit the compound ,then use the ends of it to reach where you need to polish. I mostly use the white on wood, I have used jewelers compound on metal. 


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  • 1 month later...

Looks like splendid progress Francis. Stones can be shaped to fit the job, and are best for maintaining flatness, or blending contours. After that, before the brush/abrasive grit polish, I am using rubberized abrasive wheels that are either whole or cut to shape(hand-held, not in rotary tool). Scrapers have their place for detail, but I find do not work well for leveling.

An InstaGram post:  https://www.instagram.com/p/B3FTYf4HWBL/

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Thank you so much for the advice. I have this kind of wheels but did not think about using them that way! I've used bullet point silicone rotary polishers with good results, but it took me some time to accept that using them for this purpose with the rotary tool, even at slow speed, was just asking for trouble ;) 

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