Much to our surprise we found light blue on both the LaGG-3 and the MiG-3 was extremely similar. FS35352 was extremely close match to the blue on LaGG-3 (wooden/fabric surface). The blue on MiG-3 was also very, very close to that, both on wooden and metal surfaces. In fact the blues are so close that they most probably are same paint.
No surprises there! The Lagg-3 undersides are
glossy light blue. Top is matt (flat) olive green and black. So, undersides were painted with "old" AII Lt Blue, top was painted with "new" matt AMT paints. This confirms what Vahlamov and Orlov has:
Blue AMT-7 was introduced later than green AMT-4 and black AMT-6, sometimes in 1942.
Averin writes in his article that blue paint AE-14 was introduced for undersides for MiG-1 and MiG-3 after the end of 1940 (Averin 94, p. 24). Averin's article has also a table where two other underside blues are given, AMT-7 Nitrolak for wooden and fabric surfaces and AMT-28M for metal surfaces. Start of use for both is given as 1941. So russian records have at least three different paints for aircraft undersides.
You may discount AMT-7 Nitrolak from the trio, see above. AE-14 appears in Averin's and Pilawskii's research only
underside of the Vesivehmaa Mig-3 tail and undersides of its wings are definitelly painted with different paints - paint is peeling from the tail while wing paint is like new. Those two light blues may look very similar of the same, but I would still make one on metal parts slightly lighter.
Again, Light blue is just blue, not grayish blue and it's glossy.
HTH,
KL