How to use thinning scissors and avoid catching (with video)
Using thinners requires correct technique. The wrong technique can cause the notched teeth to hit or catch. If you find the teeth of brand new thinners, blenders or chunkers seem to hit or catch as you cut, stop and check your technique before you accidentally damage the teeth. Thinners are less forgiving of incorrect technique than solid-blade scissors. Don't keep using a thinner if the teeth are catching or hitting. Check your technique first before continuing.
This usually happens due to applying pressure incorrectly (to one side or the other), often with your thumb, causing the teeth to touch, or opening the thinners too wide.
When held correctly, only the top of your ring finger and thumb should be in the finger rings of your thinners, and only your thumb should move when cutting. The scissors finger rings should sit about halfway between the end of your finger and the first knuckle, closest to your nail. When cutting, your thumb should move, and your ring finer should stay still. Your thumb should move directly up and down, not side to side. If you 'push' with your thumb, cut by moving both ring finger and thumb, or apply sideways pressure, this will cause the teeth to catch.
This video below shows you correct technique and what to avoid so the teeth don't catch.