I also received 2g of 2fdck from NL recently. Mine also had a tan color and a slightly moist consistency. After an initial test of 150 mg. sublingually, I had an anoying headache next morning, that I attributed to impurities, so I decided to clean it a bit: first I left the powder uncovered overnight in a warm and dry room, which eliminated the moisture pretty well. Then I did an acetone wash, which cleared the tan color leaving it almost pure white.
After that, I am happy with the results, my later trials have been much better: strong effects and no headaches at all.
Also, I'd like to comment one thing I hve discovered about this substance: at first, I always used it insufflated, like regular K, because I was thinking it was the mos effective ROA apart from using needles. This way, 2fdck seemed like a weaker version of K, so I did not appreciate it very much.
But then I tried the sublingual roa, which I had thought not being very effective (like it happens with K), but I was surprised because it turned out to be stronger and somewhat different effects: more stimulating and psychedelic, maybe closer to MXE than to K.
Also, the effects are noticeably potentiated if I take a bit of 3-meo-pcp previously: 2 mg one or two hours before is enough to have an intense experience with just 100 mg of 2fdck.
Now this is my favourite dissociative among the available ones.