Gilding too long or at too high a temperature can cause a white fog or mist to form.
Uneven temperature or partial evaporation of the gilding solution from areas of the plate may cause wavy lines.
Careful leveling of the plate will help prevent the gilding solution from drying on parts of the plate.
Stop heating when you first see the white water vapor fumes on the surface of the plate. A strong directional light is helpful here.
The maximum temperature should be no higher than 60C. An infrared thermometer is helpful to measure this temperature.
Gilding for 3 to 5 minutes should be long enough. Fog will form if you gild more than 8 to 10 minutes.
Happy gilding