I clean these regularly.
There will be an opaque appearance (non uniform) build up of Limescale and other chemical build ups on the glass panels.
When wet they look like they are clear but don't think that you can just go in there with a pressure washer and WFP because it will not come off.
On the ones I clean we do the external roof, internal roof, internal & external glass, external cladding, all the internal metalwork (avoiding any motors and high level electrics), the glass, the floor is pressure washed, rinsing down everything, including the brushes.
I give them the option of getting the build up off the glass or just the above without getting the build up off.
I have a specific material that I have sourced, that will clean highly stained glass but have been criticised for trying to sell it on here in the past so I will not divulge what it is.
There are things out there to clean glass, to differing degrees. How much effort you put into finding them will give you the end product.
The product I found took a great deal of finding but it completely restores glass.
Allow yourself a day on it for a project and be prepared to get wet. Check with your insurance whether you are covered for works on fuel stations (if it is on one) because you need this cover.
Rob
