I had a sealant tube (not a Slime, another brand) that I tried to pump up and so much of the goo/fibers got into the (Schrader) valve stem that it prevented the valve from fully opening or closing. As a result it made a perfectly good tube unusable.
When airing up a sealed tube, is it a good idea to put the stem at 6 o'clock for a few minutes prior to pumping? How does it take to clear? Or does it matter? Is there any way to prevent sealant in the stem?