On another issue...
I used 3641 a lot last year and have found that it shrinks at a rate that is measurable in about 5mm every 6 months!!!!!
In fact I haven't seen vinyl shrink so much since the 80's
I can't fault it otherwise but this is a serious issue to take into consideration...
I would only use this material for very very short term work in no way does it live up to its supposedly 4 year life span.
SC