Type I is a white wove paper with a few red and blue silk threads embedded within the paper.
Type II is white wove with a few red only threads.
Type III is wove with a few red and blue threads embedded plus one or more "woodsy inclusions". Under 30X magnification these look like small logs (actually straw fibers).
The last type is a ribbed paper with a few red and blue silk fibers.
The difference between the early "silks" and the later silks, was the cost of silk. As the world price of silk came down, the makers of these "banknote security" papers could afford to increase the content of silk mixed in with the paper.
The best way to see these papers is by using 30X magnification (such as Radio Shack 30X mag about $10.00 at any Radio Shack).
There are very few silk fibers so the whole surface of the paper needs to be carefully scanned (scanning the ungummed back is best).
The silk threads need to be embedded into the fibers of the paper. Silk fibers gummed to the surface or perf tip don't count."
