Jump to content
Tmuir

Zinc or Tin Plate for Black Polishing?

Recommended Posts

I'm looking at having a go of the dark art of black polishing, in particular I want to learn it for restoring old pocket watches for parts that have suffered minor surface damage.

I'm going to cast and then machine my own polishing plate.

All the books talk about using Zinc for steel parts and I have read tin for gold parts, but online have read about a few people using a tin plate for steel parts.

Tin will be easier to cast than zinc, but I should still be able to manage to cast zinc, but just want to know if anyone here has tried black polishing and if so have they used a tin plate, or should I go the extra effort and cast a zinc plate?

Share this post


Link to post
Share on other sites

I have both and prefer tin. Some folks add a little silver to the tin (I've heard between 1-5%) for a little more hardness; I have a couple and also pure tin and can't tell a huge difference.

Just avoid lead or tin/lead alloy. The lead is toxic and its oxide is just abrasive enough to make polishing next to impossible.

What's more important than composition is that the block be flat and not too smooth (rough lathe finish or scratch it up with a file), and not too much polishing paste. It needs to get almost dry to hit the black polish.

Share this post


Link to post
Share on other sites

Thanks, I plan on buying pure tin from a foundry in Queensland that sells it in small amounts to hobbyists for reasonable prices so don't need to worry about the purity.

With Zinc I would of had to gone done the path of green sand casting, but with tin I should be able to just get away making the mould with just getting some hardwood and using a hole saw drill a hole through the wood and clamp it onto  another bit of wood.

Yes the wood will likely smoulder a bit, but that doesn't matter for a one off use mould.

What diameter are your plates?

Share this post


Link to post
Share on other sites

I have a few around 100mm or so. Much bigger it's just more of a pain to redress them.

 

A friend who used to make them just melted the tin on a hotplate and poured into silicon molds. Another used shoe polish tins or tuna cans.

Share this post


Link to post
Share on other sites

Thanks, I was thinking around 100mm, but its always good to get confirmation.

A silicon mould would concern me to use as its max temp is only 30C above the max use temp of tin, but I guess if you are careful it could be ok.

Share this post


Link to post
Share on other sites

I ordered last Friday 3 kilograms of high purity (>99%) tin from a foundary, its currently in the post and should arrive late this week. (Cost a fortune)

Its my son's birthday this weekend so I doubt I will get a chance to cast the plates this weekend, but when I do I'll be sure to take photos of my whole process.

Share this post


Link to post
Share on other sites
I ordered last Friday 3 kilograms of high purity (>99%) tin from a foundary, its currently in the post and should arrive late this week. (Cost a fortune)
Its my son's birthday this weekend so I doubt I will get a chance to cast the plates this weekend, but when I do I'll be sure to take photos of my whole process.
3kg you'll have everything in a 1/2 mile radius polished. Joking of course, that's really cool. Do you have a tripod/bolt tool?

Share this post


Link to post
Share on other sites
17 hours ago, nickelsilver said:

3kg emoji23.png you'll have everything in a 1/2 mile radius polished. Joking of course, that's really cool. Do you have a tripod/bolt tool?

I bought enough to make at least 3 polishing disks, so I can use different ones for different diamond pastes.

I have in the post a tripod tool for polishing flat parts, but not screw heads, if I cant find one soon for a reasonable price It will likely become a project for me to make one.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing

    No registered users viewing this page.

  • Topics

  • Posts

    • Another Timex today. This time a 1974 model/caliber 25 based, 23550 02574 - "possibly a Marlin" but the experts will no doubt be better placed to give me an exact model. This arrived unable to wind or set, which was down to a broken wind/set rocking bar. A suitable replacement was extracted one from a donor movement, and after a quick service and polish, and a fresh crystal this is the result. Another very 1970s curly font black and white dial.  Clean and readable and running well.
    • Unitas Calibre 6325 Service Walkthrough Pictures - Disassembly (Please sort the pictures by name in ascending order) For the disassembly sequence to make sense it is very important that the pictures are sorted by name in ascending order. Generally, the sequence of pictures first shows the part to be removed in its position on the movement and the following picture shows the removed part separately. Unitas Calibre 6325 Service Walkthrough Pictures - Assembly (Please sort the pictures by name in ascending order) For the assembly sequence to make sense it is very important that the pictures are sorted by name in ascending order. Generally, the sequence of pictures first shows the part to be assembled along with any screws holding it in place. The following picture shows the section of the movement where that part is to be assembled along with my lubrication suggestion, and the picture after that shows the part when assembled on the movement. The Unitas calibre 6325 is very similar to the Unitas calibre 6498 which is the course movement on watchrepairlessons.com. Unfortunately, due to its increasing popularity, the Unitas calibre 6498 is becoming more and more expensive, although there are inexpensive Chinese clones. So, in my opinion, Unitas calibre 6325 is an excellent and inexpensive option for the course. As a matter of fact, there is a version of the Unitas calibre 6325 having a bridge configuration that looks to be identical to the Unitas calibre 6498. You’ll find plenty of watches housing the Unitas calibre 6325 on eBay. Unitas Calibre 6325 links: bidfun-db Archive: Watch Movements: Unitas 6325 - mtr-Ranfft Unitas 6325 - 17jewels.info „Wehrmachtswerk“; Unitas 6325 - Junghans Vintage
    • I have a Witschi Chronoscope S1 (1st gen, no touch screen), with automatic mic I bought new about 12 years ago. Before that I used a B200 with Gradoscope for amplitude for years. I needed to print out the tidy little sheets with timing in 6 positions for a big client so there went 7000 of the best bucks I ever spent on tools (and I have literally tons).   Would have about 10,000 cycles on it at an average of 3 per day which is pretty conservative, quite likely more like 20k. It's industrial gear for people who make money with it. They rarely come up secondhand because they rarely break and folks just use them and use them. I'd hate to have to go back to something less.   But obviously it's way overkill for someone who works on watches for fun. Unless they have the cash and enjoy top level gear (I know a couple of collectors who have Witchis). The new Chinese stuff is great, and it's about time. Before it was available a serious collector or watchmaking enthusiast had to mess with computer programs and all the hassles of interfacing the watch to that, or dig up an old paper tape machine which still command more than a weishi if functional.    
    • Hej Igen,  Yes there are two different stems on cousine and it is as you say with or without shock. Below I compiled a small list one can use.   (OME2601321) OMEGA 260 OMEGA 261 OMEGA 265-266 OMEGA 267 OMEGA 280 OMEGA 283 OMEGA 284 OMEGA 30SCT2 OMEGA 30T2PC OMEGA 30T3 (RONDASTAFFS1856) OMEGA 26.5 OMEGA 26.5T1 OMEGA 26.5T2 OMEGA 26.5T3 OMEGA 262 OMEGA 281 OMEGA 30 OMEGA 30SCT2 OMEGA 30T1 OMEGA 30T2RG
    • You just fit the barrel cap on with the small hole in line with the small hole in the barrel 
×
×
  • Create New...