Lid or No Lid?

[tding]

After viewing a "double" casting pot setup on this site I thought it a good idea to have a molten supply of lead to refill my main casting pot (which is regulated by a PID) so that the PID settings don't have to reset and I don't have to wait for the fresh ingots to melt. I choose to use a gas stove for the "refill" pot. The question is: what are the pros and cons of using a lid on the refill pot while waiting to refill the main pot?

[bbqncigars]

Pros: less time to melt; cons: having to mess with the lid.

[runfiverun]

i use a 1/2" thick steel lid on my magma and 1/4" on my lees.
i leave a little slot to slide the ingots in, in the front corner.
it gives me a place to warm the ingots before putting them in the pot and to warm up the mold while the alloy is melting.
it has saved me some messes when i get a little water in an ingot or sumthin.