Cleaning existing grille cloth

i was cleaning up my old HD 150, and ran across the quandry of how to clean the grille cloth, especially since it's backed with plywood, i didn't want to soak it too much.
i started with a mild soap and water solution, with not much success, then i tried scrubbing it lightly with one of those fingernail brushes that come in hospital scrub kits- very soft, but still not much luck, and i didn't really want to scrub the thing that much either.
what i ended up doing, believe it or not, was using windex, letting it soak for a minute, and blotting it with a clean, dry towel. i did this a few times, removing more and more of the brown liquid that i can only assume was years of accumulated cigarette smoke, or whatever.
the bottom line is that it sparkles and looks close to new. the results were much better than i expected. you can't tell where the old MM emblem was anymore(it was gone when i bought it)
i just took some pics last night, i'll post links if they are good enough to be able to see the difference.

cool havnt tried windex before. I wait till a hot day (28C+) using a spray bottle with a mild bleach water solution, pretty diluted, then i hammer it with the hose, dries really quick. Have done 3-4 amps that way with no dramas, although they dried quik as stated. Im sure it wouldnt be difficult to wreck the ply with water.

I just tried using Windex to clean the grill cloth on my new (to me) HD-150 head. It worked great! I taped plastic over the paper tube chart, then put the front panel in the sink and gave it a liberal soaking with Windex.
There wasn't much effect at first but I let it sit for five minutes then hit it again and the brown literally FLOWED off. I gave it a rinse with water to get the leftovers out and SHAZAM!
Sparkles like new now. By the way it had sort of a dead horse mixed with windex smell for a couple of hours until it dried. OK now though.
Now I just need new knobs and a re-cap and I am good to go.
Thanks greg!