I hope this is the right place to ask. I noticed earlier tonight I had a very old can of paint thinner that is now leaking. There isn't very much paint thinner left in it but I went ahead and put it in a bucket and left it out on the balcony - it is cold in my area. I also covered the parts that seemed to be leaking with duct tape. I won't be able to bring it to a hazardous waste drop-off site before Saturday since everything is closed on Jan. 1, so I'm wondering if there is anything else I can do to make sure it is stored safely until I dispose of it? Should I put the can in a Ziploc bag for example?
When containing petroleum-based solvents it is best to place them in a metal or glass jar that can be sealed. Empty paint cans or preserve jars work well (but be sure to re-label the new container to avoid it being misconstrued for anything other than it is).
Trying to patch an opening with tape on a solvent filled vessel will not hold very long as the solvent will dissolve the adhesive. A better solution to patch the can is to wrap it with foil and than tape. Or transfer the thinner into another container.
Another temporary option is to pour the liquid into an empty five gallon bucket no more than half full. Leave the bucket in a place that will not get it spilled. The solvent will evaporate in several days.
The best solution would be to pour the liquid into another metal or glass container that can be sealed to prevent evaporation.
Some plastics may also be acceptable; see my question about plastic containers for a table showing what can safely contain what.
Reminder: always label containers clearly, and remove any old labels. You don't want to risk someone misunderstanding and, for example, trying to use paint thinner as a cooking oil! As an additional safety precaution, try to avoid using containers whose color or shape suggests food to hold anything toxic.
Short term, I would drain it into a glass or steel jug or can and leave the empty container outside, capless for a month to evaporate the residue. Then recycle it.
Rather than dump or deal with household hazardous waste, I dispose of unwanted paint or paint chemicals by mixing them into viable paint, paint something I don't want, then throw it away.