Most photo frames, poster frames, certificate frames and picture frames consist of a wooden frame and a pane 
of glass. The picture frame moulding (frame) is often finely finished with gold or silver foils or leaves being a few micron ( very thin) thick. Many household cleaners contain ammonia, solvents and abrasives and shouldn't be used to clean frames lest the finish .. or colour of the frame come off accidentally. Perhaps the best way to keep a picture frame clean is to gently dust it regularly to prevent the dust and dirt build up.
If it really needs solid dirt removed, you can use a microfibre cloth with tepid water. The clear glass pane can be cleaned with a cloth moistened with glass cleaner or water. Do not spray directly on to the glass surface lest some liquid seep under the glass and stains or damages the artwork. Antique, gilded, gold-leaf picture frames however are in a class of their own because the applied silver or gold leaf is thin and delicate.
As a first note, if you know the frame to be particularly valuable consult a fine arts conservator before attempting any cleaning or restoration. Be that as it may, you can start by carefully removing the old gilded photo frame or picture frame from the wall and placing on a table. It's difficult to clean a picture frame hanging from a wall. You might accidentally dislodge it, cause it to fall to the floor and damage the artwork.
For thorough and complete frame cleaning you may have to de-frame the artwork and separate it from its backing, glass and picture frame. Once the picture frame is on a safe work table, you can prepare a cleaning solution. Mix a 50-50 solution of rubbing alcohol and clear ammonia or acetone, or a mixture of 1 cup of water with 2 tablespoons of white vinegar added. The cleaning solution should be applied with as little hand or finger pressure as possible.
For this reason, brushing it on is a good idea. Choose a brush with long, soft, flexible bristles. An artist's brush or an old, clean, natural bristle shaving brush would be ideal. You might like to test or experiment on a small section of the frame first, to make sure you got the cleaning solution or mixture right. Paint the cleaning solution onto the picture frame and wait a quarter of an hour or so for the grim the soften and loosen.
Swish the brush in clear water frequently and use it to rinse the dirt away from the frame. A gold, silver or metal-leaf picture frame should not be dried by wiping with a cloth as rubbing it may remove some of the thin, delicate leaves. A batter way is to shake away as much moisture a possible then stand the frame in a cool, well ventilated place until the remaining moisture has evaporated.
Additional useful and helpful information on how to clean and care for gold-leaf and silver-leaf picture frames may be found by scrolling down to the bottom of our Picture Frames and Art Care page.
Whatever you do when cleaning a picture frame or a photo frame DON’T spray the glass directly with a spray or atomizer bottle !! I was doing that to 2 of my wedding pictures and then the cleaning fluid ran down the bottom and inside the gap between the glass and the picture frame. It stained the paper mats under it !! The wet marks didn’t dry off clear and left grey stains of the 2 mats of the 2 picture frames. I couldn’t stand the blasted stains looking at me everytime I went into my lounge so I took my 2 pictures to a picture framer and I had to pay $168 to have the mats changed. I’m so annoyed !!!!
I have several old, framed maps and charts in my surveyor’s office. Some have been framed a long time and do look old, yellowing and tired. I find that all you need to do to make a picture frame look new sometimes is to get a new mat for the picture frame. My picture framer always cleans or recommends new glass, and that, together with a new mat, makes all the difference for me. It’ like giving inexpensive facelifts for my picture frames
I can’t believe it people give advice on how to clean photo frames or picture frames! What’s the matter with everybody? Doesn’t anyone know how to do anything anymore? What’s wrong with a bit or war water, a gentle dish washing liquid and a sponge? Jeez, how hard can that be?
Well if dish washing liquid worked, we wouldn’t need to ask. I have a particularly difficult problem on glass. My paintings were stored for years and mould grew inside the glass. I’ve dismantled it all and dried it all out. Matt’s were replaced, but the shadow of mould persists. Yes, I’ve cleaned a lot away, and you can’t see it unless you tip the glass but it discolours the artwork behind and has to go. It is like a greasy substance. Where the mould was is clear but it looks like the spores have been shifted into a corona around it.I’ve tried, 2 brands of window cleaner, vinegar, bleach, bicarbonate soda, gumption, water,metal razor scraper and left it in the sun. It disappears when wet and returns in a fine mist like you’ve breathed on it. Can mould ‘eat’ glass like lichen does to rock? It’s like I have a fine etching. Nothing seems to work. AAArrrggggghhhh!!Help!
I wonder if there’s a good reason for wanting to keep the old picture frame glass? Maybe it’s old, cast glass, the method used before float glass was invented? The surface of old picture framing glass was never perfectly smooth but slightly porous. Mould spores may well have lodged and died slightly below the surface. The mould caused the corona which is now embedded in the glass. In my experience, this is because the chemical properties of the glass silica have changed. This is permanent and can’t be cleaned off, unfortunately. Your local picture framer should be able to supply a replacement glass pane.
The glass is only 9 years old and good quality, but cast or float I don’t know. But I do think you may be correct about the spores.Certainly explains/confirms its permanence. I can’t shift it. I wanted to solve this as I have a further 10 glass pieces that will need replacement. A cost I can barely afford. Is it possible that my cleaners/cleaning transferred the spores lf so what should I do to prevent this, if anything. Thank you for your kindness delivering such tragic news. Cheers.
Your glass is definitely float and most likely, imported. Up to 10~15 years ago most picture framers bought locally made sheets, from AGI and other glass manufacturers. These have all closed now or simply stopped making glass here. This is why we’re getting porous, green yellow, brittle and dis-tempered glass which is made to mainly to meet 1 criterion, the lowest cost. That said, we’ve been framing long enough to tell you that the mould corona is nearly impossible to get off. But I do remember a job many years ago that involved getting the mould off an antique, 100 years old, cast glass pane that the customer badly wanted to keep. What we did was to bathe the glass inside an old tub with a mixture of 10% sodium hypochlorite,industrial bleach for a couple days. We used breathing masks and thick rubber gloves. From memory, that worked and the customer was happy. On the matter of prevention, mould will not grow in ambient sunlight and fresh air. Shoving picture frames under beds, inside closets, in car garages, etc., is asking for trouble. You can search here with the keyword ‘mould’ as I’m sure we have other posts on the subject. If you give me a size of your glass I can tell you what we’d charge for the job so at least you’ll know how much your local picture framer ought to be charging you.
Why do people make everything so complicated? Cleaning picture frames isn’t that at all. I’ve been cleaning my wall photo frames and picture frames with Jif Cream liquid cleanser and they always come up looking like new. I just squirt a little Jif in a damp sponge and away I go. I just rub into the the dirty frame gently and watch the dust and dirt come off. Easy!