Joe a heat gun will not work successfully because there is more to it than just heat involved. The reason for the cloth is three fold one, to hold the liquid two, stop the hot iron scorching the wood and three act as the steam generator. When you apply the hot iron to the cloth you immediately start to generate steam also preventing the steam from leaving the cloth in that direction, this in turn increases the pressure in the cloth in fact for a split second you do get some super heated steam generated so with one way of escape blocked it exits the cloth on the wood side driving its self into the wood hopefully raising the dent by re moisturizing the woo fibers. I have found toweling to work better than any other cloth because it holds a lot of water mix.
