What's the trick to get them to work? I have tried and tried and never got a pattern onto fabric with those red pencils.
I don't know if there is a trick, but what I do is this: sharpen the pencil, press firmly while tracing, set my iron at the highest heat the fabric can stand, use the steam setting, and only move the iron veeeeery slowly across the design. It takes about 45 seconds on each section of the design for a good dark transfer. Pressing for 60 seconds makes it even darker, but I can't reuse the tracing if I do it that long.
There is another brand of the red pencils that I can't make work, no matter what. The design transfer rubs off while I work. So I stick to the Collins.