[CliffordK (OP)]

I went ahead and sprayed my canola dormant spray in my orchard today.

However, as the sprayer got down to between ½" and 1" in the bottom, it started loosing the ability to spray.

So, it got me wondering.

Why don't sprayers of all sorts (pesticide, paint, household cleaners, etc) have cone bottoms, such that the pickup hose is always at the bottom, allowing use of about 99% of the spray..  And, it would also be more spray angle independent.

I suppose one would want to put on a false bottom to keep it from tipping over when filling. 

[RD]

If the liquid had any particles in it a clog would be far more likely with a conical bottom than tapping-off the liquid 1cm from the bottom which would leave the particle-laden dregs in the flat-bottomed container.

[CliffordK (OP)]

Good point.  However, it depends on how many "particles" one is expecting in the solution.

One could still do the pick-up above the bottom, just over a smaller area but the suction might suck in too many particles (if they are there). 

Many premixed commercial products such as window cleaner would essentially be sediment free.

[graham.d]

I think the answer is much more prosaic. With most such products that are sold where the sprayer is disposed of when empty, the cost of the packaging far exceeds the cost of the liquid. Basically the manufacturers don't care about not using all of the liquid. If all the liquid was able to be sucked up it would make no difference to the cost of the product. The psychological impact on customers, who they wish to think otherwise, may be good for them though; so they may have missed a market advantage here! As they say, and is often the case ... "there is no relationship between price and cost". On the other hand if you are buying a re-usable sprayer, then the cost to you of filling it up when it's near empty (as opposed to completely empty) makes no difference.

[CliffordK (OP)]

Except, if it is a mixed solution, then one often likes to use up the solution, then clean one's equipment.

Even if the solution isn't normally mixed, I tend to like to have a one-way movement from the source container to the temporary container for use.

Right,  with some disposable sprayers such as window cleaner, one can consolidate containers, and the manufacturers may not consider the customer using up 100% of the product.  The more "waste", the more that is sold.

However, it would be a marketing technique, and manufactures have always liked selling air (required by the false bottom).

[graham.d]

Really it does not make too much difference but I suspect, like me too, it is just annoying when something is designed with an obvious flaw.

[Bored chemist]

Because they would fall over?

[JP]

Because they would fall over?

Yep, and if manufacturers built supports to stabilize it, customers would complain that they're skimping on liquid, since they didn't just build a flat bottom and fill it.