Guillaume Rosin

Note: im a beginner violinist and ive only used 2 rosins before.
1 no-brand cheap rosin. And the Bernardel rosin.
The Guillaume really does make a big difference to the sound. It sounds deeper, darker and richer, more romantic.

However, in my climate (24c indooors, 50-60% humidity) it is sticky already out of the cloth, unlike Bernardel which is a tiny bit sticky but still "dry".
So ive had enormous difficulty actually applying this rosin and getting it to rub off on the hair, it feels like the rosin just glides and the hairs never grip to rip off the much needed fine dust.
Compared to the Bernardel which feels like sandpaper when applying, so you really feel and know how much youve applied and that it sticks in the hairs.
This is all with pre-roughing the rosin ofc.

I actually had to put the Guillaume in the fridge for 10min, to cool it down and make it more "dry", to get it to apply properly on the bow hair.
Your mileage may vary.

It produces a gorgeous rich deep tone, but can be a nightmare to apply.
What takes 2 strokes with the Bernardel takes 20 strokes with this.
(Now i understand why Ray Chen sits in his videos furiously rubbing this rosin on his bow for 15 solid minutes lol).