Eclipse No 101 Adjustable Scribe

This morning I had delivered a new to me vintage Eclipse No 101 adjustable scribe.

Some light surface rust, but the base is blued in a wonderful mottled/marble finish, would this be achieved with heat and then in oil or cold? I know bluing can be by either but just wondering if the MARBLED effect can be reproduced at home?

I was told recently that leaving lightly rusted steel to soak in WD40 for a few weeks is a very gentle way of removing corrosion, if I put the whole thing in to soak is it likely to affect / remove the bluing?

Last but not least what is the vertical knurled knob for?

Cheers

Chris.

To make minor adjustments to the height of the scriber point by tilting the vertical column.

Emgee

I think back in the day molten Cyanide salts were used as one of the ways to get the finish you describe, the vertical knob is for adjusting the scriber point / DTI in a vertical direction [up or down]. I can't see that WD40 will affect the bluing.

Tony

Ha! so it does, so much to learn!

Cannot see Boots selling me cyanide salts, not that I'd want them!

Thank you both!

Chris.

Aren't these case-hardened?

PS Just checked the catalogue - they are.

Edited By ega on 29/01/2020 16:00:24

For the non blackened parts, try soaking for a day or so in vinegar.
I just save what's left over from a jar of pickled onions, and decant into a larger container.

Wash of the then softened, rust in hot soapy water with a fine wire brush; I use one of the little ones with stainless bristles, as they are even gentle on the hands.

N.B. use hot water and dry the part immediately on an old towel; that you used hot water assists here, as the last remains of the dampness will evaporate. The part will surface rust again in very few minutes.
Spray with WD40 or similar whilst still warm.

The procedure removes the rust, but still leaves a pleasant patina on an older item.

I've done this with various very rusty tools from car boot sales etc.
Even a solidly seized pair of pliers can be given a new lease of life with little effort or risk of damage.

Bill

Don't re-black it or re-blue it. Save the original patina. It took many decades to build that up and it can't be replicated. That's authenticity.

That's the way it's going with vintage motorcycles these days. Unrestored, tatty, original but useable "survivors" are worth more money than immaculate restorations in some cases.

Edited By Hopper on 30/01/2020 00:08:51

The mottled blue finish used to be applied to small arms back in the 1870's but I doubt that they used cyanide, more probably pack carburising.

An old book that I have gives the procedure for hardening by cyanide salts and carries on to say that the mottled finish is achieved by quenching from cherry red in a solution of one pound of sodium nitrate in one gallon of water, with the parts being quickly moved in and out of the solution during quenching. I'm not sure if the hardening part is necessary if only trying to give the mottled finish.

Brian

Edited By Brian H on 30/01/2020 07:32:36

Thank you Bill, ok great that's another method to try out and good to know it works.

Thank you also Hopper, yes thankfully the marbled blue base is in good condition save for a few rust spots on the underside. I will most certainly be keeping the original finish on that part, the rest needs some TLC. Part of my day job is restoring old lighting so I know the value of saving and preserving patina.

Brian thanks again, yes this answers the question of how it was likely done...and also given the chemicals involved I think I will have to be satisfied with a non mottled/marbled blue.

Ok off to work for me,

Cheers

Chris.

The Finnish on the base is caused by the case hardening process and the company I worked for had there own plant and as part if training we made our own including the hardening under supervision as the molten salts were like a volcano if you got any liquid in there. They are mainly used for comparison with a dial indicator in the knuckle, checking heights against slip gauges or a height gauge and still do.

David