I thought all glass containers were the same? I am learning about wick size, it does take practice for that. I'm trying to learn. Oh and for the FO's I got them from Candle Making sites, & followed the usage rates for candles on each FO.
Each fragrance is compounded from different materials, so the scent throw and burn quality is different for each. Sometimes you have to adjust the usage rate. Some of them never work well, so people normally test more FOs than they end up using. Some fragrances will require a different wick size. For all these reasons they have to be tested individually. Get the ones you are interested in, but later you might have to narrow it down or try a similar fragrance from a different supplier.
Containers work completely differently depending on their diameter, shape, and even the thickness of the glass. If you use the same candle formulation in a different container, you have to test again. It might require a different wick, or the container might not work well. Some are difficult to wick properly.
Waxes burn and melt differently. If you have a candle designed and tested, and then you make it with a different wax, the chances of it working the same are slim. The scent throw will also vary. For instance, CB-Advanced resists frosting and helps you get a smooth top without much expertise required, but at the cost of scent throw. It works well with fewer FOs than other waxes, which means much more fragrance testing.
To test a candle, you burn it for 3 or 4 hours at a time. Let it cool completely between burns. Continue until you get to the bottom, because the burn will change along the way. By the time you get to the bottom, all or most of the wax should be gone from the sides of the container. You might not get a full melt pool (wax surface completely melted) with every burn, especially at the beginning. Often it's better that way. Wax hangup that you see on the way down may clean up by the end. You are looking for a reasonable size flame, little or no soot on the glass, no very big mushrooms (black blobs that form on the tip of the wick) though a little mushrooming can be okay, and you want to make sure the container doesn't get super hot to the touch. It can burn someone or crack. You also want to check the scent throw. It can vary with the FO, the amount you use, the wax and the wick. With the wrong FO or wick, you might get very little throw.
Some suppliers suggest wick sizes for various waxes and container diameters. Until you have more experience, it's okay to use those as a starting point. Often they will be wrong or not even be close. Generally you will want to make multiple candles that are the same except for different wick sizes to see which works the best. You can maybe start with one to make sure you are at least in the ballpark.
Most people trim the wick to 1/4 inch before each burn. They do that because the standard safe usage instructions on candles always say to do it, so they test according to the instructions. By trimming like that you will probably end up selecting a larger wick size. I personally wick the candles so they work well when you light them without trimming the wick. Most people don't trim anyway. This results in a safe and more reasonable wick size.
Never give an untested candle to anyone. Keep a close eye on the ones you are testing and do it in a safe place without drafts.
It's harder than it seems at first. New candlemakers are often surprised by how much work and complication is involved in designing good and safe candles that throw scent well, but every respectable candlemaker does this whether they sell or it's just a hobby.
