I was fixing a sink drain yesterday. The tailpiece apparently separated itself from the p-trap, and I needed to re-attach it. I bought some new slip joint washers (I bought both 1 1/4" and 1 1/2" washers, since I wasn't sure which size the pipe was) However, I noticed neither of them quite worked right. I realized that the tailpiece was a 1 1/4" pipe, and the trap was 1 1/2" pipe, and there was no adaptor between them! The old washer was much thicker than the new replacement ones I bought, and is actually able to hold the two different size pipes together (for now, I guess).
Anyway, my question is: Is the old, thicker washer some kind of "adaptor washer" that is meant to join 1 1/4" to 1 1/2"? Is this a correct way of joining pipes, or did the person before me cobble this together and figured it would be ok? I have no idea how long these pipes were attached like this, but it obviously did eventually come apart, and doesn't seem correct.