I was cleaning the car yesterday and the inside of the windscreen was filthy.
"I know" I thought to myself, "I've got a litre bottle of isopropyl alcohol, that'll do the trick nicely cos that's basically what glasses cleaner is."
So I got the IPA and a clean microfibre cloth, wet the cloth with it and wiped the window. What I got was a horrible smeary mess.
I eventually sorted it using a bottle of window cleaner that I managed to find in the back of a cupboard, but why didn't the IPA work?
IPA is a good solvent for some greases (skin grease being one of them), but like any solvent there’s stuff that doesn’t dissolve well in it. I don’t know for sure what’s in windshield grime but I doubt much of it is face grease - maybe some kind of weird residue from the AC system? Either way, the surfactants in your glass cleaner don’t exactly dissolve it, but they help it break into teeny droplets that are carried away in the water that makes up the majority of the cleaning solution.
For inside the screen, the one method I’ve found reliable, even on filthy engineer pool vans, is a drop of washing up liquid and water on a window mop or microfibre towel, clean the inside of the window. Then squeegee it off and use the rag to wipe up the edges and dashboard.
Never fails and now I never bother with bottles of miracle fluid.
Years ago I was told part of that film on the inside of windscreens is plasticiser from the plastics.
I'd say they are pretty low polarity and the polar IPA just drags them about.
Washing up liquid will have hydrophilic hydrophobic properties so good for breaking the film down.
Years ago I was told part of that film on the inside of windscreens is plasticiser from the plastics.
I'd say they are pretty low polarity and the polar IPA just drags them about.
have heard this too.
Well there you go. Learn something new every day.
FWIW the magic ingredient in the spray I used was apparently vinegar.
Ammonia is the main ingredient in domestic glass cleaner (and chicken shit, hence the smell the cleaner has).
This stuff is the dogs bollocks for cleaning the inside of a windscreen. I think it was someone on here that previosuly recommended it. Apply the cream, let it dry then rub it off. Then clean the white powder off the dashboard so it doesn't look like you're giving a scaffolder a lift to work on a morning.
IPA flashes off too fast, so it just thins out the oils and smears them around instead of lifting them. Window cleaners have surfactants that hold the dirt so the cloth can actually remove it. Windscreen film is a nightmare!
Years ago I was told part of that film on the inside of windscreens is plasticiser from the plastics.
I'd say they are pretty low polarity and the polar IPA just drags them about.
Washing up liquid will have hydrophilic hydrophobic properties so good for breaking the film down.
This +1
Every so often I have to clean the inside of the screen, and it's always far stickier and filthier than I imagine it's going to be. Washing up liquid (or general multipurpose cleaner / floor cleaner), and a cotton dishcloth. Just keep going until the water comes off clean. Then squeegee and give it a once over with window cleaner (or dilute white vinegar in water).
All the vinegar does is prevent water marks.
Also, clean the dash in the same way. It's just as filthy and I assume every time the sun hit's it that grease is evaporating up onto the windscreen.
All the vinegar does is prevent water marks.
Primarily, it's there to attack limescale. Critical (and very effective) on shower screens, not so much on windscreens.
