Pure tin? Ordinary solder is an allow of tin and lead because it melts below the melting point of either; it is a "eutectic."
Tin melts around 232 degrees Centigrade. 180 to 190 degrees Centigrade are common melting points for lead / tin solder; it can be as low as 90 degrees.
It also depends on how much tin you are trying to melt, and how thick the source wire (?) is. If it's any significant amount, more than just a pure-tin solder joint, use protective clothing.
Where you gonna get pure tin solder?