... and I find that after about 5ml, the carto performance is starting to degrade noticeably. Does this seem to match up to you guys'/gals' experience?
As others have mentioned, the nicquids you use can mean
everything when it comes to cartomizer life. A couple of examples from extreme ends of the scale:
I've been loving me some fruity nicquids lately -- watermelon, honeydew, melon explosion -- and have been using all three of those in unmodified cartos and some tanks lately. All of those cartomizers have been lasting quite literally for over two weeks of use with multiple refills per day. All of these nicquids are pretty much 80/20 or 70/30 PG/VG and are relatively thin and clear.
Conversely I recently reviewed some wonderful-tasting natural extracted tobacco nicquids and taken as they came, I was very lucky to get two to four refills out of a cartomizer before the draw became tight and the taste became "off" (or worse). Because these nicquids were extracted from real tobacco they contain a high amount of particulates / suspended solids (despite at least three to four stages of filtering) which I strongly suspect serve to clog up the fill material and build up on the coil, drastically affecting the cartomizer's performance. This problem affected every cartomizer I tried included our beloved Volt cartos.
Unfortunately, neither color nor thickness is necessarily a good way to tell whether a nicquid is going to be problematic. I've had darker, thicker nicquids (in particular, a nice Irish Cream that I tried) that seemed to last almost as long as those fruity ones, while some of the problematic tobacco nicquids mentioned above are a light, transparent blonde color and not really all that thick. It is the actual flavorings that are most likely determine whether the nicquid is a carto-killer or not.
For those nicquids that do degrade cartomizers quickly, it
may be possible to make them less damaging. The particulate density can be reduced by thinning them with some straight PG and/or perhaps a bit of PGA or vodka, provided that the flavor is strong enough to be satisfying when thinned this way. With the tobacco nicquids above, this allowed me to get the nicquids working well about 1.5x to 2x as long as they did "as-is".
As others have suggested, it is a very good practice to dedicate
one cartomizer to a new nicquid and if it is not the only flavor you vape over day or few, keep track of refills before performance drops off. If it goes a long way, great; if not, consider whether the taste is good enough to be worth your time and if so experiment further with thinning to see if you can make it last a bit longer. You might also consider getting in polite touch with the vendor and presenting them with your experience; if they value you as a customer they should be up-front about the ingredients, let you know if they or others have had the same experience and whether they are looking into different flavorings, filtering methods, etc.
Hope this helps!
ditto
