I've been told that there's a professional product for cleaning glass that various frame shops use.
The one nearest me just uses whatever from the local shops so that's no help so can anyone tell me what's the best glass cleaning product out there and where can I find it in the UK?
Nilglass is one, also used by the double glazing trade. Usually sold in the UK by Cash & Carries, double glazing trade suppliers.
Personally I also use screen wash diluted, it smells similar to Nilglass and works just the same, both clean without harming the glass and leave no residue, or drying marks.
You should always use ammonia free glass cleaner on the side that will be inside the picture frame. We use Sprayway ammonia free glass cleaner. It comes out as a foam instead of liquid. My framers feel it is a little quicker and leaves less film than Windex. It is available at Walmart. For acrylic, or touch-up we use Brillianize which not only does not have anything like ammonia, but
it is even safe to drink.