Why the need to wipe between drops when testing for TA?

[GuinnessPhish]

According to the directions in the TF 100:

"Add r-009 one drop at a time, swirling between each drop. Wipe the tip of the bottle after every drop with a damp cloth"



Is this really necessary? What difference does it make?

 

[JasonLion]

Static electricity can build up on the dropper tip, which changes the drop size, and throws off the test results. In theory this can happen to any of the tests involving dropper bottles, but in practice it is only at all common on the TA test. A damp cloth/tissue shorts out the static charge, restoring the drop size to normal.

 

[jblizzle]

This also only appears to be a real problem when the kit is new. The drops were practically shooting out of mine new kit. Now it appears there is no more issue.

 

[duraleigh]

Yeah, it is a transient condition usually lasting only a couple of weeks.

Too many newbies read that and start wiping down every reagent on every test.....total waste of your valuable time. I have never seen it on anything but the R-0009.

 

[HamburgerChef]

This also only appears to be a real problem when the kit is new. The drops were practically shooting out of mine new kit. Now it appears there is no more issue.

Good to know. I have a new kit and have been having weird #'s. Maybe I am not totally incompetent after all.

 

[spidey07]

You can tell if this is a problem. You get "small drops". It's difficult to describe but the best way is you don't see those "nice, plump, full drops" that seem to drop from their own weight. Believe it or not a drop is a fairly accurate and consistent measurement based on surface tension.