It's a little bit awkward to find that the Italian camouflage picture is either fairly straightforward or that we’re missing an awful lot. I’ve only secondary sources to go on.

Italian armour began the war in one of two base tones.

Grigio Verde Scuro – the most common tone a dark grey green. This was at least as dark in tone as British Khaki Green G3 or Slate 34, to judge from black and white photos. Pignato suggests FS595b 35159 as a match. This is a medium-dark green with a distinct grey aspect

Humbrol 102 + black is an option for this, perhaps using 111 or even 224 to grey it if needed

Marrone Rossiccio - The alternative – seen on CV3/33 and 35 tankettes and apparently on M11/39s - was a base of brick or rust red –– with overpainting in the grey green, either as vertical bands or a small hard edged blotches. Steve Zaloga at one time refers to it as rosso ruggine.

Marrone Rossiccio is generally interpreted as a medium brick red. This shows in black and white with moderate contrast against the green. In one instance this is noted on an M13/40 as a single overall tone. Pignato quotes FS20100 as a match – in Humbrol terms 186+black may be close

All the armour facing the British in Egypt and Libya in 1940 seems to have been painted in the green or brick-red/green scheme, with the exception of a small number of M11/39s – perhaps only one battalion - which appear to have been in a hard edged three tone scheme akin to British Caunter, but of unknown colours, I think its fair to assume that the base tone – the lightest – was some form of sand. The middle tone offers relatively little contrast with the base tone, but contrasts more with the darkest than the standard red-brown does with dark grey green. The dark colour is dark enough to be the dark grey green.

From February 1941 all M13/40s and their relatives were painted sand “Giallo Sabbio” in the factory. Bovington’s M13/40 or 14/41 and L3 are a base tone very like British Light Stone, but I’m satisfied that as this goes over some earlier museum labelling its not original. However the L3’s flame trailer seems to be original, and shows a dark “Light Stone” with an overspray in something close to FS34159

Pignato offers 20260 as a match – this is close to Humbrol 93. Adam Geibel suggests a Floquil mix of RR83 Mud: M31 Yellow and RR11 Reefer White in ratio 10:1:1. He also notes a range of paints from an Italian firm called “Lifecolor”, which are otherwise unknown to me.

Mike Starmer has been given 33440 as a match and notes that this can be reproduced by a mix in Humbrol terms of 6x83, 4x93 1x24 and 1x34

Steve Zaloga suggest that whatever colour they were, it was more golden than Tamiya XF55, and when he has illustrated Italian vehicles shows a strong sand akin to Humbrol 94.

In 41-43 some Italian Armour shows up in photographs with some overspray in a contrasting tone. It is not impossible that they tones used in these schemes were new colours, but the effects created are explicable by washing out the pre-existing grey-green and brick-red.

By 1943 Italian armour was returning to darker tones, with complex blotched patterns over sand in (presumably) the grey-green and rust tones. In between sprayed patterns in one or two tones appear.

Interiors seem to have been white

References

Geibel, Adam Iron coffins: Italian Medium Tanks M13 and M14 Darlington Productions, [undated] (Museum Ordnance Special Number 2); Pignato, N and Simula, C M13/40 Profile Publications, 1967 (Armour in Profile Number 14) and particularly Italian Medium Tanks in action Squadron Signal, 2001 (Armor 39). Zaloga, Steve Steel chariot Militray Modelling Vol.30 No1, Jan. 2000 pp. 34-35. Also Zaloga’s Blitzkreig and Eastern Front cited French and Russian sections here.

ã Mike Cooper, 2004