I saw sets made of this fabric and with this impacted dust like substance start showing up in the late 80s or early 90s.
I agree with other that they are pretty well done in terms of details and they look old at a glance....but for me they all have the signature characteristics of the same origin and they are for sure fake...as far as I am concerned.
lots of these were stamped Lago Wien...and saw one recently of even more convincing fabric...maybe an "improved" generation fake that was stamped Lago Mu...or something close...looked good but was fake and I think maybe from the source of the trousers posted.
I started thinking about it more after a posted and I don't want to be held to the time frame that I gave as it may have been a little later in the 90s...I just can not remember...but I do know who had the first set that I inspected and where that was...and that I saw a number of others within the year!
You may be right about the bleach....these things were distressed artificially and really dust blasted.
Comment