HOW YOU CAN MAKE ABLUEPRINT
Gather these materials: Two shallow pans, preferably glass or plastic; a
measuring cup; a tablespoon; ferric oxalate (Fe2(C 20 4h); potassium ferri-
cyanide (KaFe(CN)6);many sheets of whitepaper;drawing ink;photographic
negatives;opaqueobjects, such as keys, coins or leaves; paper clips; a large
black folder or envelope; tracing paper ortransparentwrappingpaper;and a
clean cloth. Remember, the panscannotbe used later for cooking.
Follow this procedure:Add 3 tablespoonfuls of ferric oxalate to 3 cupsof
water in one of the shallow pans. Dip the sheets of white paper, a few at a time,
into the ferric oxalate solution and allow it to dry in a dark place. Ferric oxalate
is the chemical fortreatingthe white paper and turning it into blueprint paper.
If you are not going to use theblueprintpaper immediately, store it in the black
envelope when it is dry.
With the drawing ink, make some line drawings on the tracing paper.Attach
them to sheets of your blueprint paper with paper clips. Place the opaque
objects you gathered on other sheetsofblueprintpaper. With the paper clips,
fasten thephotographicnegatives to stillothersheets of blueprint paper. Put
theblueprintpapers with the various thingsattachedto them in a sunny place
for at least 20 minutes. Expose thetransparentpaperfor a longer time. While
you are waiting, add 3 tablespoonfuls of potassium ferricyanide to 3 cups of
water in theothershallow pan. This is the developing solution.
At the end of the time of exposure, remove everything from theblueprint
papers. Dip theblueprint papers, one after the other, into the developing
solution.Itwill only take a few seconds for the blue color to appear. When it
does, remove the papers and carefully wash away the film of chemical from the
white areas with a cloth moistened with water. Let yourblueprintsdry and
flatten them under a heavybookbefore you put them away for good.
Results:The ferric oxalate solution was colorless. When it coated the white
paper, the white paper didn't change color. Nevertheless, the whitepaper
became blueprint papersimply because it was coated with ferric oxalate: