Bartender’s Ketchup (St. Germain elderflower liqueur nickname)

Manhattan-born Robert Cooper (1976-2016) introduced St-Germain, an elderflower liqueur, in 2007. The product immediately caught on with several bars in New York City (such as Death & Co.) and became so essential that it was nicknamed “bartender’s ketchup” by 2009.
 
The Whisked Foodie blog explained in December 2012:
 
“The other great thing about St. Germain is that it is one of the easiest liqueurs with which to work. While other liqueurs can do odd things when mixed with the wrong ingredient, St. Germain is very forgiving, so much so that bartenders often grab a bottle of St. Germain to fix a problematic drink, hence the moniker ‘bartender’s ketchup.’”
 
   
Wikipedia: St. Germain (liqueur)
St-Germain is a liqueur flavored with elderflowers. It was created in 2007; the brand is owned by Bacardi Ltd.
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History
St-Germain was launched in 2007 by Coopers Spirit Co, a company founded 2006 and head-quartered in New York. In 2013, it was sold to Bacardi Ltd., although Robert Cooper of Cooper Spirits agreed to work with Bacardi as a “brand guardian” and spokesperson.
 
On Monday, April 25, 2016, Robert Cooper died at 39 years old. He was the creator and visionary behind St. Germain.
       
Drink Boston
SEPTEMBER 4TH, 2009
Operation 1919 – Part 2
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One “hard to find” item that was mentioned more than once by commenters on that first post? St. Germain Elderflower Liqueur. Hard to imagine, since its ubiquity now has earned it the nickname “bartender’s ketchup.”
 
Twitter
Mixology
‏@Mixology
“St. Germain’s ubiquity now has earned it the nickname ‘bartender’s ketchup’.” - Lauren Clark, Drinkboston.com http://arm.in/5UP
1:03 PM - 6 Sep 2009
 
4 November 2009, Washington (DC) Post, “Looking ahead to a ‘C’ change,” pg. E5:
Until three years ago, who’d ever heard of booze made from elderflowers? Now, St-Germain has become so prevalent in contemporary recipes that some have begun calling the elderflower liqueur “bartender’s ketchup.”
 
Google Books
Alcohol in Popular Culture:
An Encyclopedia
By Rachel Black  
Santa Barbara, CA: ABC-CLIO, LLC
2010
Pg. 65:
St. Germain Elderflower Liqueur, for instance, a newly released liqueur so popular that it has been called “bartender’s ketchup” because it is used in so many house specials, ages significantly in the bottle, as its botanicals age and oxidize.
 
Drink Spirits
St – Germain Elderflower Liqueur Review
By Geoff Kleinman -  May 27, 2011
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St-Germain is so commonly used in cocktail bars that it’s often referred to as “Bartender’s Ketchup.” It got this distinction for adding a light, sweet and pleasing floral note to cocktails that just need that little something extra.
 
Whisked Foodie
St. Germain: A Bartender’s Ketchup
by Phil Manning | Dec 25, 2012
It’s often referred to in the restaurant industry as “bartender’s ketchup” because this liqueur is almost guaranteed to make any cocktail taste better.
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The other great thing about St. Germain is that it is one of the easiest liqueurs with which to work. While other liqueurs can do odd things when mixed with the wrong ingredient, St. Germain is very forgiving, so much so that bartenders often grab a bottle of St. Germain to fix a problematic drink, hence the moniker “bartender’s ketchup.”
         
Google Books
Death & Co:
Modern Classic Cocktails, with More than 500 Recipes
By David Kaplan, Nick Fauchald and Alex Day
Berkeley, CA: Ten Speed Press
2014
Pg. ?:
St-Germain: This lovely elderflower liqueur has been a victim of its own success. When it was first released, around the same time we opened Death & Co, bartenders found that its potent lychee aroma and citrus flavors harmonized surprisingly well with almost any ingredient, earning it the nickname “bartender’s ketchup.”
 
New York (NY) Times
Robert J. Cooper, 39, Creator of Popular Elderflower Liqueur, Dies
By ROBERT SIMONSON APRIL 27, 2016
Robert J. Cooper, whose unusual elderflower liqueur, St-Germain, introduced in 2007, was so completely embraced by the cocktail community that it became known as “bartender’s ketchup,” died on Monday in Santa Barbara, Calif. He was 39.
 
Washington (DC) Post
Drink this cocktail in memory of the man behind St-Germain, a bartending staple
By M. Carrie Allan Columnist, Food May 2, 2016
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Elderflower syrup has been a thing in Europe for centuries; Cooper first came across it in bars in England, where he was inspired to develop it into a liqueur. With St-Germain, many Americans encountered the flavor for the first time. Cooper was quick to credit bartenders for the success of the spirit, and rightfully so: They fell hard for St-Germain, which can elevate a mediocre sparkling wine, complement the tang of fresh citrus and blend beautifully with the botanicals of gin. If a drink lacked mystery, if a drink lacked that certain je ne sais quoi, for a while St-Germain was a bar’s cure-all, so common a source of drink-patching that industry folks began to refer to it affectionately as “bartender’s ketchup.”