Hi Howard...
I think Herb has the sequence right and I was wrong...but the area is darkened, nevertheless...is it not ?
But on original lugers, I do see those patterned areas as darkened...I do not think this is just age...as I think it would go grey (if only strawed...) and not the darkened blue...
Here is a photo from a Simpson LTD offering...compare it to the result's Dan got with his 1st. strawing attemps...