Hi, I'm still pretty new to calligraphy and have spent the past couple months focusing on copperplate. I've offered to do my sisters wedding invitations - I'm nowhere near good enough to do it for money but she seems to like them. So I'm doing the envelopes, using a Gillot 303 nib and Higgins Eternal black on hobbycraft envelopes. The first day or two was fine, it even looked pretty good if I say so myself! But then I had to renew the small ink pot and everything went wrong. The nib kept scratching the paper creating tiny clumps of fibres on the tip, it seemed scratchier and jagged. I've cleaned the nib with nib cleaner, sucked the daylights out of it (after I read saliva helps), but no dice. Only things I can think are different, the fresh ink and the temperature of the day which is about 10°c lower than the past couple days.
Is this normal? I'm assuming it's just me but thought I'd check if this happens to more seasoned calligraphers and if there's anything I've done it can do.
Tia
(Ps I would put a pick of the envelopes up but I can't seem to upload a pic from my phone)