On Sat, 17 Feb 2018 23:47:55 -0800 (PST), wrote:

On Saturday, 17 February 2018 13:35:40 UTC, Harry Bloomfield wrote:
I tend to save a few of the cheap cleaner squirty bottles, to
re-purpose these for spraying thin oil and even water to spray cool a
weld down. Trouble is they soon seem to fail to spray.

Problem - often they stop spraying or don't spray as well as they did.
Thinking it might be a failing none return valve I spent a bit of time
investigating them and found that the reason they stop, is that they
get air in the trigger operated pump. The pumps or not self priming
they need to be full of liquid to work. Once air is drawn in they fail.

The fix - put a finger tip over the jet outlet, to act as a one way
valve and pump a few times to expel the trapped air.

I've got 2 that have worked many years over & over. But no idea what makes it keep going, might be handy to know.

NT

Same here - my best one can be set to Spray or Jet. I use the spray for
damping small areas (I use a filler that needs a damp substrate) amd for
mixing small quantities of filler: spray jently to fix the surface of the
powder, use jet to get water into the heap, start to mix, use spray to add
water all over until the mixture is OK.
It avoids what I call 'Polyfilla ping-pong'.
--
Peter.
The gods will stay away
whilst religions hold sway