FaithfulPastor

Veery715 makes a good point about the vapors, but I would gently diagree with the idea that it must be used outside. Good ventilation is more than helpful, but using it outside is a bit much in my opinion.

As for the harshness of lacquer thinner, it will not harm the valve one bit. It does a great job of removing any crud from inside the valve as in addition to the outside.

I fought a sticky valve problem for a long time and was ready to replace the horn. A friend recommended the lacquer thinner cleaning (also I used a rag with lacquer thinner on it and pulled it thru the valve casing). It solved the sticky valve problem on the first use.

I give my trumpets a bath twice a year (it's quite the ordeal in the bath tub with dish soap), and the valves get the lacquer thinner treatment and I've had no negative experiences at all. None from vapors, damage to metal or finish.

Had it not been for the thinner, I am not sure how much money I would have spent on the sticky valve problem... I may have ended up buying a new horn. So I am really happy with the Home Depot $4.99 cure all in a can.

Maybe my experience is different than the norm and Veery is correct in the vast majority of usages. The solution he posted above may work for many, many people. However, it did not work for me, thus I took more a aggressive approach.

Faithfully Yours,
FP