So I contacted Gtechniq about the juddering issue and as I thought they confirmed that it is technique related
Thank you for your email
We have heard of this being mentioned on some forums but it is not a direct issue with G1 product itself. As you correctly say, it will be down to the application process (prep, application & residue removal)
We also recommend cleaning the wiper blades with IPA and putting a small amount of G1 on the blades
It is also essential to apply G1 in a garage or indoor space and leave for atleast 12hours to cure (leaving the blades up if possible)
Best way to apply is below
Machine polish the glass or use our G4 polish by hand
Clean away residue with a damp cloth
Clean glass with our PW, G6 or IPA to ensure glass is squeeky clean
Apply first layer of G1 in circular motion
Leave for 5mins
Apply second layer of G1 in a sideways motion
Leave 5mins
Apply 3rd and final layer in long vertical line from top to bottom
Leave 15-20mins
Remove residue with G2 in very small sections (approx 200mm x 200mm)
Perform a final wipe with IPA or G6 glass cleaner to ensure residue is fully removed and looking clear
Clean and coot blades
Leave blades up and cure overnight