Have a recurring slow drain in my old bathtub. I usually put a little drano down it every few months.. but didn't have any today so decided to grab the plunger. Now it barely drains at all.. and I'm pulling what appears to be blue cardboard up the drain. Sink drains fine... toilet seems to be flushing normal.. although it does seem slower than most and causes lots of double flushes. After pondering the blue cardboard it occurred to me that our washer drains into a shop sink in the laundry room. Blue jean remnants coat the sink and on occasion block it from draining. When that happens I just grab the clump with my hand and its fine. I don't hear any gurgling. Can I use Drano on a very very very slow drain? I don't have a snake available right now, but if I was going to snake.. what would be the best route to go?

If you don't have access from below, then remove the overflow plate, take out the bell and go through there.

I agree with KeepItSimpleStupid,

Snake it from the tub overflow, see the image below, Thanks.

John