This article is from the July 1984 AFRMA Rat & Mouse Tales news-magazine.
By Nick Mays of the National Fancy Rat Society, Great Britian
“Cross your Rex to a ‘Shorthair’ and then you should get X number of Rex and X number of Smooth youngsters. Now, cross Rex siblings to Smooth siblings to gain more Rex and some Smooth. (Now in F2 generation) OUTCROSS Rex and Smooth (best Rex) from the F2 to unrelated Smooth stock of a fairly neutral colour which you know will not ruin the colour already in Rex (i.e., Champagne Rex crossed to P.E.W. Smooth). The F3 generation should contain some Rex and Smooth. Mate these together (always Rex x Smooth) then cross any offspring (F4) back with original line—PHEW!!! The only real difficulty arises in so far as one is dealing with three characteristics, namely colour, Rex coating, and Smooth coating, and how to keep these three traits into the desired classifications. However, inbreeding should not occur to a great extent as long as outcrossing is done every third or fourth generation or as soon as colour and type and size begin to diminish noticeably or the dreaded ‘Double Rexing’ occurs.”