Bluing hands with a spirit lamp?

[mbwatch]

I have been up to more mischief refinishing and bluing pocket watch hands again. This time though, a Breguet moon minutes hand with a slender shaft is causing me a fair bit of difficulty. I keep overshooting the color I want in an instant because it heats up so quickly over a gas burner. It goes from barely a pale straw yellow to gunmetal with almost no period of blue in between and I'm getting frustrated polishing it 4 times over to reattempt the heat treatment. It is quite different from broader hands I've done successfully, where each color stage arrives gradually.

I decided to try it over a spirit lamp as some of the old books describe, so that I could control it over a longer heating period. I am using denatured alcohol as fuel and bluing over fine brass shavings in a thin aluminum mini pie pan. I am unable to get to any color change over the alcohol burner, it does not seem to get hot enough at all in a bed of brass or placing hands directly on the aluminum pan.

Does anyone have experience bluing hands over a spirit lamp? What fuel worked for you?

I am sure I can find other heating sources around my home that work more suitably than natural gas, but I am mostly just curious if it can be done using the spirit lamp, and how old timers did it.

[Neverenoughwatches]

3 hours ago, mbwatch said:

I have been up to more mischief refinishing and bluing pocket watch hands again. This time though, a Breguet moon minutes hand with a slender shaft is causing me a fair bit of difficulty. I keep overshooting the color I want in an instant because it heats up so quickly over a gas burner. It goes from barely a pale straw yellow to gunmetal with almost no period of blue in between and I'm getting frustrated polishing it 4 times over to reattempt the heat treatment. It is quite different from broader hands I've done successfully, where each color stage arrives gradually.

I decided to try it over a spirit lamp as some of the old books describe, so that I could control it over a longer heating period. I am using denatured alcohol as fuel and bluing over fine brass shavings in a thin aluminum mini pie pan. I am unable to get to any color change over the alcohol burner, it does not seem to get hot enough at all in a bed of brass or placing hands directly on the aluminum pan.

Does anyone have experience bluing hands over a spirit lamp? What fuel worked for you?

I am sure I can find other heating sources around my home that work more suitably than natural gas, but I am mostly just curious if it can be done using the spirit lamp, and how old timers did it.

A thermostatic hot plate?  Very non traditional. How big is the pan ? The heat might be dissipating too quickly from the focused area, I used a small  brass clock mainspring barrel. 

[mikepilk]

In the UK we have a fuel for spirit lamps, camping stoves etc called methylated spirits, which is denatured alcohol. I use the same set up as you - fine brass shavings in an old watch case I attached a handle to. I have had no problems in bluing hands. The temperature of a spirit lamp flame is about 1000°C. 

Maybe try a small pan with less shavings ?

[oldhippy]

I used to blue loads of clock screws on an old penny and a spirit lamp burning methylated spirit when I got to the colour I needed which was a nice rich blue I would drop them in oil this would keep them shiny.  

[mbwatch]

5 hours ago, Neverenoughwatches said:

How big is the pan ? The heat might be dissipating too quickly from the focused area,

It's about 12cm, and thin aluminum so yes fast dissipation is strong possibility. I've been trying to find something brass but have nothing around the house.

 

4 hours ago, mikepilk said:

fine brass shavings in an old watch case I attached a handle to. I have had no problems in bluing hands. The temperature of a spirit lamp flame is about 1000°C. 

Now there's an idea I had not though of. I have a pile of poor quality brass pocket watch cases I will never use for anything else. The size would be right and thick brass rather than thin aluminum.

My spirit lamp produces only a dark orange flame with hardware store (not lab grade) denatured alcohol. Which is labeled as "alcohol stove and marine fuel" on the can. It feels hardly any hotter than a wax candle, so I wonder if I am not setting up the wick correctly. It's been fine for shellac work, but this seems different.

4 hours ago, oldhippy said:

I would drop them in oil this would keep them shiny.  

I wondered about the purpose of quenching in oil rather than water. Thank you.

[mikepilk]

6 minutes ago, mbwatch said:

It's about 12cm, and thin aluminum so yes fast dissipation is strong possibility. I've been trying to find something brass but have nothing around the house.

12cm, that's huge   You would need a blow torch to heat that !

This is what I use, an old watch back about 3cm.

The flame feels much hotter than a candle.

 

[mbwatch]

I am not getting the blue-purple flame at the as in your photo, only a crackling orange flame. It's an inexpensive glass alcohol lamp I think I got from Cousins, and the cotton rope wick might be inadequate. Next I'll try fraying the wick more so I'm burning fuel over more surface area and thus more vapor.

[nickelsilver]

Ethyl alcohol is denatured in numerous ways, sometimes changing the color of the flame. I have tried several brands available from grocery/hardware stores here and found that they don't all perform the same- some are sootier, some don't seem to make quite the same amount of heat. But even those get plenty hot enough to blue small watch parts. I use a small brass pan similar in size to Mike's caseback pan, with fine brass filings in it, perhaps 3-4mm deep. Just a teaspoon or so.

 

For a watch hand, to get the most even color, you want to heat it very slowly. Like take a good 5-7 minutes or more to come up to color. A pan with a handle makes it easy to distance it from the flame to allow the color to develop gradually. Taking time like this will let the color equalize nicely; a typical problem with a hand is getting too much color quickly on thin areas, while thicker ones lag behind, and when they've caught up, the thin areas are too light. Playing the pan over the flame even once certain areas are a deep blue lets the others catch up while not overheating the already-done areas. Letting the blue develop over time also seems to make a more robust (thicker?) oxide layer.

 

You'll have to do a few to get the knack with your pan and lamp. The next most important thing is cleanliness. I take already clean hands, lay them on a clean piece of paper, and rub over them with freshly cut pithwood wetted with benzine (lighter fluid is fine). 99% iso alcohol is good too. Blow off any stray bits of pith with a blower (not your breath!!).

 

If you have fresh brass filings, heat them in the pan for some time before use. This will burn off any contaminants, you will almost certainly see some smoke, and you don't want that happening when going for an aesthetic blue.

 

Here's my pan with the amount of filings I tend to use.

 

 

Edited October 21, 2024 by nickelsilver

[mbwatch]

So I narrowed to two issues.

First: My lamp's wick was generally too low, which I had done to keep it from burning up too quickly. Exposing more wick and fraying it more gave me a larger, bluer flame. Though the larger flame is short lived because the cotton wick does burn away quickly.

That flame is far above the temperature needed for bluing. I could blue directly on the open flame in seconds, and also reach red hot almost instantly on smaller pieces.

Second: My 12cm aluminum pie pan was acting as a heat sink. On only the thinnest test hands I could achieve an uneven bluing if I omitted the brass shavings and left them in direct contact with the aluminum. Even still that would not work for larger, thicker hands. So I sacrificed my little pie pan with some tin snips to produce this jagged little cup about 5cm across.

In here I could blue small thin hands over the brass bits, very slowly and only after I reduced the brass by 3/4. But large ones still can't get past a brown color to the purples. This is a big one, about 18 size. To get this color I had to heat it on a small square of aluminum. Even against the bare metal cup right on top of the flame it could not go past brown. My test hands come from a big ol' assortment I have of old stamped steel unfinished, unblued hands. I cleaned them in 99% IPA but did no polishing. This isn't meant to look nice, just experimentation. I can do a lot better.

Lesson I think I have learned: Aluminum is pretty unsuitable as a bluing pan over a spirit lamp. It works fine over a more aggressive heat source like a natural gas burner, but it loses heat much too fast to be very effective. My brass shavings (from ebay, I have no lathe to be producing my own) - are clearly much coarser than @nickelsilver's

Edited October 22, 2024 by mbwatch

[mikepilk]

It would help if you cut down the sides of your pan until it is nearly flat. 

I made my brass shavings by filing some brass.

[Neverenoughwatches]

I think the biggest problem you have here is the use of aluminium for your pan. Aluminium conducts heat fast, too light, the heat is dissappearing too quickly, you need a metal that will absorb and store the heat evenly. Why cast iron is used for heating systems  and is good for cooking with, so definitely steel, and thickish would be good.

[mbwatch]

Yes, I am done with the little aluminum pan, I will be going through my spare cases to see what else I can find. But original question answered - yes the flame from denatured alcohol is hot enough, the heating medium matters more than expected.

[SwissSeiko]

1 hour ago, mbwatch said:

Yes, I am done with the little aluminum pan, I will be going through my spare cases to see what else I can find. But original question answered - yes the flame from denatured alcohol is hot enough, the heating medium matters more than expected.

I made a small bluing pan out of some brass stock that I turned into what looks like a mainspring barrel, and filled it with brass shavings.

[mbwatch]

I pulled the hinged caseback off a cheap 1970s pocket watch and blued some hands in it this evening. It worked fine, but still took way to long to reach temperature over the alcohol lamp, >10min. Once heated, it was at least able to consistently keep on bluing without needing to reheat a lot. I thought it was brass, but whatever the base metal actually was began to get a little bubbly and melty. Surprising. Not a good choice for repeated use. I still need to go with a smaller pan or use natural gas instead of the old-school lamp.

[Neverenoughwatches]

58 minutes ago, mbwatch said:

I pulled the hinged caseback off a cheap 1970s pocket watch and blued some hands in it this evening. It worked fine, but still took way to long to reach temperature over the alcohol lamp, >10min. Once heated, it was at least able to consistently keep on bluing without needing to reheat a lot. I thought it was brass, but whatever the base metal actually was began to get a little bubbly and melty. Surprising. Not a good choice for repeated use. I still need to go with a smaller pan or use natural gas instead of the old-school lamp.

How about an iron or brass  1 inch cap nut for gas pipes ?

Just now, Neverenoughwatches said:

How about an iron or brass  1 inch cap nut for gas pipes ?

You'll need more than an oil burner to get it up to heat quickly , then switch to the lamp to maintain the temperature. 

You can also get your shavings by reducing the walls of the brass one with a roughing file.

[ChrisInOz]

Clickspring has some interesting thoughts about the process in this video.  He did stress that it's a good idea to use thick brass as this helps to keep the temperature stable for an even bluing effect. As @Neverenoughwatches said above, you would need a stronger heat source to bring it up to the starting temperature.

He used a lathe and mill, because, of course, he has them, but it should be possible to make a simple version of this one with hacksaw and file..

Maybe try the brass cap nut first. It looks like a lot less work.

[mikepilk]

5 hours ago, mbwatch said:

I pulled the hinged caseback off a cheap 1970s pocket watch and blued some hands in it this evening. It worked fine, but still took way to long to reach temperature over the alcohol lamp, >10min. 

I don't know what's going wrong, but I just tried an experiment. I put some brass filings in my watch case dish, and blued a large screw. Over the spirit lamp on a medium flame, it took exactly 60 seconds to turn blue. 

[mbwatch]

3 hours ago, mikepilk said:

I don't know what's going wrong, but I just tried an experiment. I put some brass filings in my watch case dish, and blued a large screw. Over the spirit lamp on a medium flame, it took exactly 60 seconds to turn blue. 

Looking at the photo of your lamp up the thread, I wonder if yours with the ribbon shaped wick is heating a lot more efficiently. Your watch case pan is smaller I suspect, probably at most only 2/3 the size of the pocket watch caseback I used last night. This is an interesting academic exercise at this point.

 

7 hours ago, Neverenoughwatches said:

How about an iron or brass  1 inch cap nut for gas pipes ?

I will give it a try! However, that is going to be a tight fit for a lot of what I do. 18 size pocket watch hands are usually >20mm in length so I would be short on clearance. I will need to go a little larger for practical use.

[mikepilk]

4 minutes ago, mbwatch said:

Looking at the photo of your lamp up the thread, I wonder if yours with the ribbon shaped wick is heating a lot more efficiently. Your watch case pan is smaller I suspect, probably at most only 2/3 the size of the pocket watch caseback I used last night. This is an interesting academic exercise at this point.

The ribbon wick does give a much stronger flame. 

The case back I use is quite thin, so heats quickly, but with enough brass shavings, is controllable for getting the correct colour.

[mbwatch]

1 hour ago, mikepilk said:

The case back I use is quite thin, so heats quickly, but with enough brass shavings, is controllable for getting the correct colour.

You know, the other thing I realize now is that I have been testing all my pan prototypes by grasping them in a clamp - either vise-grip pliers, or an old jeweler's hand vise, both thick steel. So in comparison to your thin brass wire embedded in wood, that's a great deal more heat loss / more time spent heating the pan to a workable starting temp. I will need to insulate my gripper before I get around to affixing a permanent handle.

[Neverenoughwatches]

1 hour ago, mbwatch said:

Looking at the photo of your lamp up the thread, I wonder if yours with the ribbon shaped wick is heating a lot more efficiently. Your watch case pan is smaller I suspect, probably at most only 2/3 the size of the pocket watch caseback I used last night. This is an interesting academic exercise at this point.

 

I will give it a try! However, that is going to be a tight fit for a lot of what I do. 18 size pocket watch hands are usually >20mm in length so I would be short on clearance. I will need to go a little larger for practical use.

Pipe fittings come in bigger sizes if you need them from 1/2 " to at least up to 3" 

[SwissSeiko]

44 minutes ago, mbwatch said:

You know, the other thing I realize now is that I have been testing all my pan prototypes by grasping them in a clamp - either vise-grip pliers, or an old jeweler's hand vise, both thick steel. So in comparison to your thin brass wire embedded in wood, that's a great deal more heat loss / more time spent heating the pan to a workable starting temp. I will need to insulate my gripper before I get around to affixing a permanent handle.

You're not too far from me. I'm in  eastern SD. I can send you a a little brass pan if you need.

[mbwatch]

@SwissSeiko Thank you for the offer - I may hit you up if I fail to produce something myself.

[SwissSeiko]

7 minutes ago, mbwatch said:

@SwissSeiko Thank you for the offer - I may hit you up if I fail to produce something myself.

honestly, if you have an old pocket watch mainspring barrel, that is essentially what I made.

[mbwatch]

I have my working solution. This started out as a 2 way liquor shot pour with 0.75oz and 1.5oz stainless cups pointing different ways. It hasn't been used for its intended purpose in decades. I was able to snap the larger cup off at its weld and then cut down the smaller cup with a Dremel cut off wheel. I did a haphazard effort at filing the sharp edges away and tested it out. That plastic rim at the top of the handle might melt if I left it in the flame, but the pan heats so quickly I don't think that will be an issue.

It turns out that cheap modern pocket watch caseback I was using yesterday is made of something like zinc, brittle and powdery. Also explains why it was bubbling after 10min over the flame.

This one took only about a minute to heat up to a working temperature over the alcohol burner, the handle does not get hot. And some random parts from a watchmaker junk drawer lot blued in under a minute. That wheel, looks like maybe it was from a verge escapement? It looks beautiful.