I have several Estwing , now then - the blue handles , when they first came out the material was quite firm , later on they changed to more of a cushion grip.
I have used a 16 oz (E3-16C) for flat-roofing (felt tacks & 3" nails for sheeting) where hands and gloves come in contact with bitumen for many years, this I have cleaned a few times using White Spirit (Turps Sub.) - this is the original blue handle type.
For better work I do like to use a Vaughan with hickory handle , however I have broken too many hickory handles on framing. Having said that these hammers were by Lock Tools , a British firm no longer in existance , I would say not as good as the best Stanley of the day. For framing - I use Carpenters or Rip , normally 28 oz. depending , I don't use these to often and not quite got the hang of a true framing length yet (Sometimes I drive 6" nails home with a 2lb Engineers - these have heads of the same size as not ball pein).
Incidently - I am a engineer , this last year I have "invested" in a few enginners sizes, I had held off because of oily work. Considering the new softer shock reduction grip may not like white spirit - I decided to ask Estwing Technical about this - their reply was that the handles were quite good against oil contact , cleaning - use CITRIC hand cleaners.