People often find cutting opalescent glass more difficult than transparent. My observation is that people exert too much pressure in scoring opalescent glass by listening for the creaking/scratching sound.
Not all glass is made the same, even by the same manufacturer. But all the same rules apply in scoring opalescent as transparent glass. However, they sound different.
No more pressure should be put on opalescent glass than transparent. Only about two kilograms (5 to 7 pounds) of pressure is required to score glass sufficiently to create the weakness that we exploit when running the score.
If you concentrate on keeping the pressure on both types of glass the same, you will hear different things. On transparent glass you normally hear a creaking or light scratching sound and you do not get a whiteness along the score line. If you hear same sound on opalescent glass, too much pressure is being applied.
The same pressure (2 kilograms) on opalescent glass gives only a rumble of sound. No creaking or scratching is heard. You can test this by placing a piece of glass on kitchen scales. Zero the scales with the transparent glass on it and score. Note the pressure you used. Now zero the scales with a piece of opalescent glass on it. Ensure you score to the same pressure as on the transparent glass by looking at the readout on the scales.
Just as excessive pressure on transparent glass leads to erratic breaking of the glass, so it does on opalescent glass. You will need some practice to stop listening for a sound and begin to feel the pressure you are applying to the glass. Once you do apply the same pressure to opalescent as to transparent glass, your success in scoring and breaking opalescent glass will increase greatly.
Scoring and breaking opalescent glass successfully is the same for both transparent and opalescent glass. Use moderate pressure and don’t listen for the sound.
Feel the pressure. Ignore the sound.