How much screen wash to water is 20% to 80%

531063

Just put a eggcup full in, if it doesn't clean the screen just keep adding eggcups until your happy with it, all this ratios is clever marketing by the companies so you use more than you actually need.

Idontlikeworking

Mildly_Miffed said:

Idontlikeworking said:

I'm no good at maths so can someone work out how much screen wash and water I need.

I bought a 250ml bottle of screen wash that says to use 20% Volume and 80% water so how do I work out how much is 20% and 80%. The place I bought the screen wash said it will make up to 4 litres so I'm thinking there ratio is 50ml screen wash and 800ml water but is this correct.

It's very straightforward to work out this kind of proportion.

20% concentrate to 80% water
...knock the 0 off and ignore the %.

2 bottles of concentrate to 8 bottles of water
...half that

1 bottle of concentrate to 4 bottles of water

1 x 250ml plus 4 x 250ml = 1250ml, a litre and a quarter. Nowhere near four litres, obvs.

Yes, you can mix it thinnner - but it's not going to work as effectively, and come winter it'll freeze more readily.

Your suggested 50ml to 800ml...
50:800
...knock a zero off

5:80
...double

10:160
...knock a zero off

1:16

So you'd be putting four times as much water in as they recommend.
1 x 250ml plus 16 x 250ml would be one bottle to four litres - so four and a quarter litres.
I wouldn't bother with it that thin - you might as well just use neat water.

If you really wanted their "4 litres", then you're forgetting that you already put a bottle (of screenwash) in out of the 16 total to make four litres - so you'd add 15 of water instead.

If you find the mixing proportions confusing, it might be easier just to buy ready-mix screenwash.

Or just shrug, chuck the full bottle in the empty screenwash tank, then top it up with water...

If 1x 250ml bottle makes 1250ml then I will need 5 bottles which will cost just over £20 so a bit expensive.

I normally use holts concentrated screen wash and that tells you to use 9/1 nine parts water one part screen wash. 

chrisw

It's fairly cheap stuff and doesn't make much difference. Put the whole bottle in and then fill to the top with water.

CliveOfIndia

I'm loving the comments on this one

Have to say I agree with what a lot of the other folk have said - just pour a decent glug into your screenwash bottle then top it up with water, it'll be near enough (a "glug", of course, being a precisely-defined SI unit of volume   ).  Arguably it's more important to get the ratio correct in winter, to stop the washer jets freezing over, but in summer a guesstimate is good enough.

If, for whatever reason, you decide you do want to get the "correct" mixture, then it's just a 4-1 ratio.  Fill a container with screen wash then add 4 containers of water.  It doesn't matter what the container is - a teaspoon, an egg-cup, an old (well-rinsed) milk carton, a 2-pint measuring jug, whatever you've got handy (OK, the egg cup and teaspoon were tongue-in-cheek, but you'd still get the right ratio).  As long as you use the same container to measure both liquids then it's one container of screen wash to 4 containers of water.