U436 (Purple) V U436A (Dark Violet)

I know scanners and monitors don't always do justice to color variations, but is it safe to say that this represents the two color differences between U436 (Purple) and U436a (Dark Violet)? I believe they are both Die 1s:

They sure "look" like purple v. dark violet.

However, the real way to tell the difference between U436 and U436a is by the watermark in the paper.

Watermark 19 and 20 are always dark violet. These are 1915 watermarks and are U436a.

3 cent envelope production then ended for a bunch of years and resumed in 1932. In 1932 they were still using 1929 paper contract product. These later 3 cent envelopes (U436) generally are printed in purple (as in your scans), but there are examples of envelopes with U436 watermarks and very dark purple ink.

Last watermark for U436 is #43 (1949), I believe.

Thanks for the info. Unfortunately the cut square doesn't show any remnant of a watermark, so all I have to go by is the color for identification. Since I've been through a couple of hundred of these cut squares and none are as dark as what I presume is the dark violet (U436a) scanned above, the best I can do is make an educated guess.

Notice in your scan, the purple dude has a band across the middle with decreased ink saturation. Whazzup with that? What's the back look like?

The backs don't look like much. Here's a scan of the same two cut squares in the same order:

"The backs don't look like much. "

I agree. However, if you get a hankerin' to send this guy to the shredder, give me the opportunity to make you a ridiculously low offer. As an EFO addict, I couldn't resist it.

The dark violet issues were used to pay first class plus the 1 cent war tax rate. When WW I ended, the war tax ended and there was no need for the 3 cent envelopes. Eventually, the first class postage rate increased to 3 cents and the existing dies and a few more were put into production. Color on the 3 cent purple ranges from the bright purple specified in the contract to a shade that rivals the dark violet of the war issues.

The interesting streak across the U436 is solvent related.