I've been doing a bit of work on adapting some older formulae from R.H. Angier's classic book, 'Firearm Blueing and Browning', ISBN 0811706109. I plan to blue some test pieces with these, to see how they compare, and how well they work.
Thought I'd put them up now, in case anyone else would like to try them out.
These are two 'rusting solutions' that have very good practicability, as they are based on Zinc Chloride - very readily available, in the form of 'Baker's Soldering Fluid' from Bunnings.
The other chemicals these contain, Hydrochloric Acid and Copper Sulphate, are also very easy to get hold of. Bunnings, or farm supplies stores for the Copper Sulphate.
I'll give these in 'w/v', or 'weight for volume' units of measurement. The weights are easily converted to grains, for weighing out using a powder scale - no volumetric glassware!
Grains = grams x 15.43. Both are for a final volume of 100mL.
Formula A
Adapted from Angier Ab. 11, p.70 'Zinc Ammonium browne'
Baker's Soldering Fluid: 24.75g
Hydrochloric Acid, 32% w/v, SG 1.16: 2.5g
Distilled Water: to final volume
Formula B
Adapted from Angier Ab. 1, p. 68 'Copper-Zinc browne'
Baker's Soldering Fluid: 8.25g
Copper Sulphate: 2.50g
Hydrochloric Acid as above, a few drops if solution is cloudy
Distilled Water: to final volume
Making up solutions
Safety: PPE in the form of eye and hand [rubber gloves] protection is strongly advised, when mixing and handling any of the chemicals and solutions herein. The mixed solutions are both DG Class 8 [Corrosive], and Class 6 [Toxic].
1. To a glass or plastic container with a calibration marking at 100 mL, add about 50mL Distilled Water.
2. Using a small plastic container - e.g. an old film can or a suitable bottle cap, weigh out the main liquid ingredient/s, and add them to the water in its 100mL container. Swirl to mix.
NB: A disposable plastic 'transfer pipette' makes this job easy, they are available on FleaBay or from scientific suppliers.
For example; https://www.wiltronics.com.au/product/7 ... ck-of-100/
3. Weigh out any solid ingredient, say onto/into a piece of aluminium foil, and transfer this to the 100mL container. Stir to dissolve.
4. Finally, with distilled water, make the solution volume up to the 100 mL mark. Suitable storage containers are glass, or HDPE plastic.
Note:
To prevent after-rusting, it is essential to run the workpiece through a 'neutralising bath', after a satisfactory blue is obtained.
The easiest one to make up is a Caustic Soda [Sodium Hydroxide] bath, at 40-50g/L in rain or distilled water. The workpiece is left in the bath overnight at room temperature. Caustic Soda is available from supermarkets, in the cleaning section, or hardware stores.
Edit: Just went in today to buy a new bottle of Baker's Soldering Fluid, and it has the actual Zinc Chloride concentration marked on it [400g/L]. As this is a bit weaker than I had assumed [by picking the centre of the concentration range given in the MSDS], I've adjusted the numbers accordingly.
