Canada Bk82 & Bk82A Uncoated Vs Coated

These booklets came in 10 cover designs and were issued with coated and uncoated paper. I recently purchased an auction lot of 40 which was supposed to consist of 10 of each BK82 (coated and uncoated) and 10 of each BK82A (coated and uncoated). While the difference between BK82 & BK82A is obvious, the coated vs. uncoated has me puzzled. What is the easiest way of telling these apart?

I could be wrong but I think the coated are shiny. Hold them up to the light.

Thanks. That is definitely one way, but when all of the panes more or less have the same sheen it still doesn't work.

However, I think I have found a way that seems consistent. By using a strong magnifier I was able to determine that the paper appears to have very fine diagonal lines associated with it. For what I assume is the coated paper, these diagonal lines are more pronounced and definitely glossy. I sorted through the 40 booklets just based on that and low and behold I ended up with 19 in one pile and 21 in another after one pass. I also noticed that in the pile of 19 which I figured were coated paper, the 5 cent stamp was more brownish in shade. So based on this 2nd identifier I quickly found the missing 20th booklet in the pile of 21. So I think I have it figured out.