I am not completely sure myself on Swedish stamps.
However, this quote from Filahome in the Netherlands says that the ink would show through on the back.
http://www.filahome.nl/e/stamp-coll...stamps_a.htm Quote:
Aniline
Aniline colors are distilled from coal-tar. Ink made of these colors is used as the basis of certain dyes in postage stamps. Aniline ink immediately penetrates between the fibres of uncoated paper.
Aniline has been used particular to produce a bright-red ink. Aniline is soluble in water and the colour shows through the back of the stamp.
Aniline ink has been used in printing Roosevelt small dies proofs.
Posted 03/27/2012 8:32 pm
