Tomato blossom set hormone - how to use?

I have had a plastic spray bottle (mechanical, not pressured) of "Tomato Hold" for probably over 20 years. Of course, I read the label, but it's not very thorough. Roughly, it says to spray flower clusters when most of the flowers have opened to prevent blossom drop when nighttime temperatures are much below 55 F.
I wondering a few things:
1. Firstly, of course, is my bottle still good after 20+ years.
2. Spraying with the bottle seems strange. 99% of the fluid won't get anywhere near a blossom. So, instead I spray just one burst into the plastic cap and take a tiny artist's brush and dip into the cap to get the brush wet. I dab the brush onto the blossoms. Been doing this for years with evident success, but who knows. One never knows what affect this is having, but I've been getting pretty early tomatoe set even when nighttime temperatures drop to 50 and below.
3. Do I want to dab the yellow part of the blossom, or the green back, or both... or does it matter?
4. Do I want to dab the smaller unopened blossoms at the same time?
5. Will blossoms I don't dab with the solution benefit? Or do I have to dab them all?
6. Do I have to come back later and dab the unopened blossoms when they have finally opened?
I've been growing Early Girl exclusively for some years, having enjoyed pretty good success with them. I used to try various others, but have settled on Early Girl. It's cooler than many places here (Berkeley, CA flatlands), there's often days when it's cloudy in the mornings or even all day some times. Nightime low temperatures now are averaging around 49 degrees (+ or - 5 degrees more or less), and my first blossom sets are pretty much open now.
Dan
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Dan Musicant ( snipped-for-privacy@privacy.net) wrote:
Tomato Hold
"This product is now cancelled"
<http://www.pesticideinfo.org/Detail_Product.jsp?REG_NR 548100186&DIST_ NR5481>
Seems like not something to have about.
Bill
--
Garden in shade zone 5 S Jersey USA

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On Sat, 25 Apr 2009 09:41:39 -0700, Dan Musicant ( snipped-for-privacy@privacy.net) wrote:

That old stuff was kind of nasty. You can get something called blossum set spray which is a natural plant hormone. It's supposed to help, but I've never found it necessary.
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