I got confused - there's more 5-TMa in the Swenson formula than I had stuck in my head - I the tone of the American formula above would land a bit darker than I illustrated.
Without a doubt the USN colo(u)r here would be different to the Royal Navy colour, going only by the red pigment.
It's worth pointing out that the British used two distinct blue-black pastes and it might be worth asking Michael to remind us which one this formula used (I suspect Admiralty Pattern 370A)...
A single 7lb can of Admiralty Pattern 370A Blue-black paste turned 77lb of white pigment oil paste to Home Fleet Grey (Admiralty Pattern 507B, or Admiralty Pattern 507A, or G10) colour.
A single 7lb can of Admiralty Pattern 371 Blue-black paste turned 78lb of white pigment oil oil paste to Mediterranean Grey (Admiralty Pattern 507C, or G45) colour. This paste was also used in colours B15 (a double shot, plus a lot of pure ultramarine), B30 (just shy of a triple shot) and B55 (a partial can).
Clearly Admiralty Pattern 370A is much stronger staining than Admiralty Pattern 371. Whilst of tangential interest here, it's worth point out that blue-black paste can have significant differences in its influence depending on inert pigment extenders which must be present in AP371 to bulk it up to a stiff paste but such that the whole can makes a light grey out of a basically similar volume of white base.
The inference here is that we cannot assume parity between whichever of the RN's blue-black pastes is used here and the USN's blue-black paste. Even the choice of black pigment used can have a greater or lesser effect, and when such a small weight of black and ultramarine pigment has such a drastic effect on a large white weight, selection and proportions of the specific black pigment and the proportions of ultramarine to black are critical in arriving at a vaguely similar shade.
The red however is instructive. There is simply much more of it in the British paint.
There's a bit of an inconvenient incompatibility with composition here in that as you know the USN 5-x paints were made by adding pints of 5-TMa blue-black paste to 5 gallons of 5-Ua untinted white base.
Zinc white paint has a density of approximately 1.4 x that of water. 5 US gallons of water weighs approx. 42lbs. 5 US gallons of white paint therefore should weigh in around 59lb, but it will be weaker than British stiff oil paste, to which further oil and thinners would be added. A pint of water weighs roughly a pound, so we should probably boost up the assumed weight of 5-TMa also. Ultimately this might get us to an appearance a bit lighter that 5-H, which should have 2 pints of 5-TMa to 5 gallons of 5-Ua.
I imagine the American formula above would result in something a bit like this, if my assumptions about the behaviour and characteristics of the American base ingredients are correct (I may need to reconsider this if they're not - it's not an area I'm strong in):
Thanks for the formula.
This is interesting, but when compared to the formula in the Swenson memo, there are differences in "ratios";
Swenson Formula .............................................. RN Formula
White Lead Oil Paste 28 lbs ............................. RN has 56 lbs
Zinc Oxide 50 lbs .............................................. RN has Zinc Oxide White 24 lbs
Liquid Dryer 3 Pints ......................................... RN has Liquid Driers 3 Pints
Blue/Black Paste (5TM) 7 lbs .......................... RN has Blue/Black Paste 1 lbs
Red Cake or Venetian Red 1/4 lbs .................... RN has Venetian Red 2 lbs
Raw Linseed Oil 21 Pints ................................. RN has Raw 16 Pints and Boiled Linseed Oil 8 Pints
White Spirits none in SWENSON's formula ... RN has White Spirits 2 Pints
Where as the "White Base" components are about the same, 78 to 80 lbs, there is a big difference in the Blue/Black component, 7 to 1 lbs, and eight times as much Red component in the RN formula (2 lbs) than the Swenson formula (1/4 lbs).
I don't know how these two different formulas ingredients when mixed would look like, but I would think that Swenson's formula would be less red and more Blue-Gray.
FYI, the RN formula issued 16/4/1942 under CAFO 784 was White lead oil paste 56lb, Zinc oxide white 24lb, liquid driers 3 pints, Raw linseed oil 16 pints, boiled linseed oil 8 pints, white spirit 2 pints, blue black paste 1 lb and Venetian Red 2lb.
The CAFO also stated that the formula results in a tone which is a little lighter than previous formulae and gives a tone halfway between 507C and 507A.