As far as I can recall, I was the one who tested lemon juice and the effects it had on fruit flavors. At the time I was also using sucralose (ezsweets) in fruit/bakery flavors. I also tested distilled vinegar (not acv, I dont use it) on tobaccos.
What I found with fruit and bakery vapes is they were great initally with the additives, for about two days. Then on day 3 like clockwork the sharpness/crispness of the flavor was just... plain... gone. It never rebounded either. It just continued decline. So I started testing the same juices with lemon juice and sucralose separately. Trying to find the culprit. The result in my tests was that they BOTH decrease flavor output of ejuice. While they help initally boost and sweeten flavor, within a few days, they both cause ejuice to simply go flat. While its a more dramatic example, I feel the same way about ejuice with lemon or sucralose as I do about flat soda pop. Its just lackluster.
This occured in both high VG bases at 80% and high PG bases at 80%. I tested both because I didnt want people calling me out saying VG mutes flavor, which to this day I refute as utter nonsense.
I no longer use either in any of my mixing. I have found that using fruit flavors with alcohol bases provide more than enuff sweetening o. their own if they are steeped for 48-72 hours, and it helps that I use 80%VG in my juice.
As far as tobaccos go I also agree vinegar that after a few days it can flatten flavors over time. However!!! As I vape mostly tobacco ejuices I still add 1 drop/5ml of distilled white vinegar to my vapes. To counter the flattening I adjust by adding slightly more flavoring. About .5% to 1% more flavoring in a final mix. In my experience this counters the effect of flavor flattening with DV and allows mostly all tobacco vapes to round out immediately. (note: i also heat steep my juices at a constant 150° in a water bath in a crock pot for four hours after mixing and have found it it adds about 2 weeks to the aging process of ejuice). At the 2 weeks mark (in my case then this is 4 hours after mixing), all of your tobacco flavors will have a spike in flavor and will stay there, but only round more given time. Giving you a spiked up flavor but still rounded body to your vape. I found apple cider vinegar made bad and good juuces worse with no spike at all, but to be fair I barely ever tested acv.
All of my vapes... yes read that as ALL... are primed and full bodied in four hours. Period. Ultrasonic isnt the answer either. Hand shaking is enuff for juice. Heat allows flavor dissipation and release FAR FAR better.
Alot of what I do flys in the face of common and well "documented" processes others use like ultrasonic steeping tho. (if it works for ya, great. I know what I know and heat is the key, not vibration. And yeah, I tested that too about three months ago so I stand behind it).
People just pretty much ignored my testing. I took painstaking measures to control the samples and.prove to myself the results. Today when people say they use lemon juice, or sucralose and RAVE about the results.... I know they are NOT vaping stellar juice. They are absolutely, positively, better off without both. Unless they are going to vape what they make in under two days.
Note: I did not bother testing the effects of citric acid powder in juice, but I assume it has the same effect as lemon juice and mutes flavors.
Well then, having been initially convinced that a heated ultrasonic was 'the way to go' for steeping, and having used it for months (each blend getting 4, 30minute sessions with heat around 150 degrees), but finding that MANY juices still need more steeping to finally 'settle in' - we decided to try the "4 hours @ 150" that buffaloguy was kind enough to discover, painstakingly test, and share.
We've just completed almost 7,000ml of various juices (largest size of bottle was 60 mls, so that's a LOT of different flavor combinations - including some tobaccos). And you know what? ALL OF THEM THAT WE'VE MADE BEFORE (many that had to have a couple of weeks after the 2 hours in the ultrasonic) ARE PERFECTLY STEEPED.
We used our food dehydrator set to 150 degrees, and left them in a minimum of 4 1/2 hours, uncapping/burping, recapping, and shaking thoroughly every hour or so. We left them in longer than 4 hours to ensure they actually got 4 hours at the full 150. (EDIT: with a few of them, we weren't able to give up our 'ultrasonic addiction', so a few got 2 hours at 150 in the ultrasonic and the remaining 2 hours in the dehydrator). We're putting that noisy contraption on the back shelf (unless we need to use it 'for heat' over the summer when our dehydrator is busy with garden produce or making herbal concoctions).
buffaloguy, we seriously appreciate all the time & effort you've devoted to testing & posting. This kind of data is exactly what the DIY forum is sorely lacking in, and it's the kind of data that makes ALL the difference to successful, exceptional juices. KUDOS & THANK YOU!
I recently performed a very controlled test on ACV versus no ACV. What I have found is:
1) The initial flavor of a tobacco mix with ACV seems better. The overall flavor was smoother and the taste seemed to be enhanced.
2) After a few days aging the mix with ACV changes very little, perhaps slightly muted.
3) The initial flavor of the same mix without ACV was harsher and less balanced. The taste seem to be diminished.
4) After a few days aging the mix without ACV had smoothed and balanced considerably, and the overall taste was similar but stronger than the mix with ACV.
This is very speculative, because different mixes might exhibit different results, however my initial impression is that ACV "seems" to enhance flavor initially, but I believe this is because it may in fact attenuate the total flavor. Initial suppression of some harsh notes could give the impression that the "good" flavor was stronger simply because some harshness that might interfere was suppressed.
After a little aging the harsher elements of the mix without ACV seem to diminish and the result is also a smoother more balanced taste , but also stronger flavor because the "good" flavors are less affected by harsher notes, and now more prominent by virtue of also not being diminished by ACV.
So in summary I believe ACV diminishes flavor, giving an impression of "better" flavor initially but at the cost of total flavor. Brief aging without ACV allows the harsher notes to decline without the better flavors having been diminished as well, and the final result after just a few days is a fuller, equally smooth blend but more overall flavor after a little aging.
Until I decide otherwise, although ACV has been a standard in all my tobacco blends for a long time, I am now currently eliminating it entirely...
PS: At some point I also experimented with dilute citrus flavors - not to add citrus taste but with the intent of pH modification with a milder agent than ACV. I have not repeated those in a controlled experiment but I believe my conclusions were similar - lowering pH by any agent may result in "improved" initial taste but ultimately diminished tobacco flavors...)
Of course YMMV ...
And RobertNC, thank you, TOO (very very much!). We've been sharing this information when we get the time and some folks have been grasping it and using it successfully (well, actually 'not using it' successfully

)
Hopefully we can all start copy/pasting this info to the newbies, and we can 'turn the tide' away from all the misinformation, and get folks back to understanding the difference between "oft repeated advice based on nothing but oft repeated advice", and actual testing & validation!