While I have a couple of ball peen hammers and forging work can be done with them, I see thatmost of the serious "smiths" have a special hammer that is flat on one end and radiused on the other, weighing about 2 1/2 to 3lb so I thought I had better get one as well. At the scrap yard last time I wanted a bit of round stock to make one and the guy asked if an old sledge hammer head would do as they had a few 'out the back'.
I found one that was about 4 lb so thought that would be a good base to work from.

I needed to shorten it a little to lighten it and after a while of cutting on one end it struck me that it would be hardened so I fired up the forge and when it had got to heat, put it in a bucket of sived ash for the night to anneal it. Made the cutting a little easier so rounded one end and radiused the edges on the other and after a bit of a clean up, put it back in the forge to heat treat, did the quench in water then tempered it in the cooling forge. Found a suitable piece of beech and knocked up a rudimentary handle and now have a hammer that weighs right and swings nicely.

The rounded end is for moving metal and making a thinning process a little quicker then the flat end is used to planish out the dips and hollowsthat the rounded end caused.