Write off professional self-employed work that I wasn't paid for?

[turnoffautofill]

I vaguely remember seeing on previous year's tax questions about whether I performed any work (part of my self-employed business, I presume) that I was not paid for.
What I am wondering is whether I may write off as an expense any travel and time spent doing my profession (teaching and playing music) somewhere that would make it more like volunteer work? For example, if I went out of country to teach low-income schools for a week. I would be able to receive documentation that the events occurred but they would not be able to pay me for it.

[xmasbaby0]

No.    Charitable donations of your time or expertise as a volunteer are not deductible.