First attempt at making cannabis vape juice. Need help!

Hello friends of rollitup and fellow Cannabis lovers! I am attempting to make cannabis vape juice from shatter and Propylene Glycol (PG).

My starting equipment includes: *28 grams of snap-and-pull 90% thc shatter. *1bottle of Propylene Glycol - Food Grade USP - 1 Quart (32 Oz.) *50 .5 ml empty vape cartridges *5 10 ml empty syringes *1 shot glass

I will be using the shot glass extraction method as seen here:
Now to the confusion! I(being an amateur at this) do not understand the ratios when cutting the shatter with the PG. Obviously, I would like to maximize THC content and amount of empty cartridges I can fill per 1 gram of shatter. The recipe calls for 2.5ml of PG to 1 gram of shatter. If I am starting with 90%thc shatter and I cut it with 2.5ml of PG, what will the thc content of each .5mL cartridge be? Hypothetically speaking, if I did a 1:1 ratio, would the thc be 45% by using 1mL of PG and 1 gram of shatter? I was considering doing 1.5ml PG and 1 gram of shatter, but I don't know how much the thc content would be. Can anybody please enlighten me on this? Thanks a lot in advance and will update with pictures and progress in the future!

Who cares??? Obviously, the less PG, the higher the THC%.

If doing everything by volume (ml), then the math is simple. If you have 1 ml of something that 90% THC supposedly and you mix that with 1 ml of something with no THC, you would end up with 45%.

Google "how to compute weighted average"..

Fuck PG. terpene suspension or nothing for me.

I go by weight
1g extract to 1g peg400 usp

Been working for over 3yrs and hundreds and hundreds of ml later.

I saw a patent where they used a mixture of PG and 1-laurylglycerol (AKA monolaurin) for cannabis vape fluid. You could probably find the patent by searching with the right phrases. Apparently it's very good for you, immune booster. It's in coconut oil btw. Probably helps the mixing of the fluid, since it's an emulsifier. Its BP is 186 C. It's a solid at room temperature, melts at 63 C. Guess that's why they didn't use pure monolaurin.

I am totally new to vaping and also want to make some oil of my own. I was told to use one part VG and one part PG. When I looked at vape juice that is what those ingredients already are, so my question also is can't I just get a bottle of nicotine free vape juice and simmer it for awhile? I got some really strong but am afraid to waste it. Sorry to invade your post with my questions, but I am looking for some good, but easy recipes myself.

VG will not stay mixed with the oil. They will separate . Straight PG will eventually as well but not as bad. PEG stays but IMHO tastes worse. I use a tiny bit of EJ MIX (which is basically a few different PEGs) and then go PG.