Yeah @Mimi Aysha - @Charles is right.  Some rosin cakes are easy to "start", a few scuffs of the bow hair across the brand new, shiny cake will cut the surface of the cake and apply immediately (I observed this most noticeably with Pirastro Goldflex and Andrea Solo).  On the other hand, some rosins do seem to be hard and shiny and won't "take" to the hair immediately without slightly roughening up the surface.   Light sandpaper, nail-file, matchbox side etc etc... will do it..

There are discussions without end on the web regarding why this should be so, and they vary from "well, it's just rubbish rosin anyway" to "it has been in storage on the seller's shelf for who knows how many years and the volatile oils have evaporated"...   

I have taken little notice of this - but also, it has to be said - I have in my early days discarded, within days of purchase, some of the cheaper cakes I tried out of interest...

Mimi Aysha said
Wonderful - appreciate the advice, thanks so much guys, new rosin is an upgrade (fiddlerman's rosin) so now I'm gonna try it...have a great day all!  

  Cool - you'll have no issues with that, I have a cake of the FM rosin as well, it's just fine!

  As time goes by, and your "feel and touch" with the bow and rosin evolve, you'll become aware of the difference a good rosin makes - and - even depending on the environment / geographical area you live in - you may well come to experience climatic effects - like when it's really, really humid, or really really dry - different rosins *may* feel marginally different.  I don't really experience this myself, we have no real "extremes" of ambient environment here, but others have reported such issues... and will change their choice of rosin depending on these external factors. (temperature, humidity)...  However, I'm pretty sure that applies to those who are in the higher-plane of playing-ability - but thought it just worth mentioning...