Does this drive you mad?
You buy a spray-gun of ready-mixed weedkiller, or aphid spray, or mildew spray: and when I say that, I mean anti-aphid and anti-mildew spray, of course... can you imagine if they sold bottled aphids? You could sneak round to your worst enemy's greenhouse and squirt a dose of them in through the vents.... no, of course you wouldn't.
Where was I? Oh yes, after a few weeks of perfect squirting, you try to use the spray-gun again, you can hear that there is still some liquid sloshing around inside, but you can't get any more out.
This is particularly the case with weedkiller sprays: most weeds are, let's face it, on the ground. Patios, paths, those angles where the wall meets the ground, that's the place where we need the squirty weedkiller, as we can't get to them with a hand tool.
So how does “one” hold the squirty bottle? You point it downwards, of course, because you don't want to spray weedkiller at random all over your precious plants, you want to accurately target the one or two bad 'uns. (You also don't want to waste expensive chemicals, or use chemicals unnecessarily.)
So why can you never get the last bit out of the bottle?
Answer, if you've ever taken the lid off a squirty bottle, you'll know that there's a slim tube that runs inside from the trigger part down to the bottom of the bottle, where it sucks up the liquid.
But it's never quite long enough to reach the bottom of the bottle, is it? And when you turn the bottle at an angle, all the remaining liquid fills up the bottom corner of the bottle, out of reach of the tube.
Honestly, I sometimes wonder if manufacturers have a special research department to come up with ideas like this.
So what can we, the poor user, do about it? If you unscrew the trigger part, you can add some water, which brings the tube back in contact with the liquid - just bear in mind that this does dilute the contents, so you have to remember to use twice as much in order to get the same effect - and eventually you reach the “plimsoll line” again. It's probably a good idea to write “Diluted” on the label, otherwise if you forget you've already done it, you find that eventually you are just spraying water!
Another trick is that sometimes, when you unscrew the lid, you can see that the intake pipe has a curve to it, and you can twiddle it round until the curve points “forward” then re-tighten the collar, which means it reaches further into the bottom corner of the bottle.
Both these tricks help to use up as much of the expensive product as possible, but basically it's down to very poor design by the manufacturers
The only real answer is to buy just one squirty gun for each type of spray - ie one for weedkiller, one for aphid/bug spray etc - and then buy the relevant product in undiluted form, and make up your own. This is what I do, as you would expect: I buy neat Glyphosate (which is pretty much the only weedkiller I will use), and undiluted Rose Clear etc, and refill the squirty bottles, as and when they are needed. This also means that the mixture is freshly made up each time, which means that it works better.
And yar boo sucks to the squirty-gun manufacturers!