This in spades!
No white gas, gasoline, mineral spirits, or alcohol!

I've got two of the Dietz #20 mid-size color black & brass = very attractive for full-time display, but bedroom size. My wife liked them so much she had me order two bigger #80's (black & brass) for living room display. One note, use lamp oil for non emergency use. It doesn't make the house smell like kerosene.

Dumb question, but I've never used one of these..... How do you put out the flame?

MPI kind of nailed it but let me give a tad more detail.

There's a little lever that lifts the globe so you don't get burned. Turn the wick down so the flame is easy to blow out. Now while your hand is still on the little knob turn the now not burning wick back up to where you can see it, just a little. That way next time you light it, you aren't fumbing around with that knob trying to figure which way turns the the wick up. A major boo boo is to turn that the wrong way and the wick goes in the tank. That's not a show stopper, but it is quite the hassle.

Tj

Obviously, you're not wicking, basically not getting the capillary action that allows a liquid to flow uphill, against gravity.

What that means in the very basic terms is your hole size in your wick is wrong.

Now there's a number of things that can cause that.

The number 1 thing is your wick is gummed or charred. Simply put you let kerosene sit in open air, like a distillation column, the lighter hydrocarbons will evaporate changing the specific gravity of the fluid. Eventually it will get so thick, your hole size in your wick doesn't work anymore and then gums up. Next if you follow how those holes pull each other then to pull they have to have somewhere to go. If your wick is charred at the end this will inhibit capillary action.

The solution to a gummed and charred wick is actually pretty simple. You take the wick out, clean it in a light hydrocarbon solvent, use scissors to trim the char, and now the most important part, let is sit until the solvent is completely dry. You don't want to blow yourself up. A lot of people use just fresh kerosene and kneed the wicks. I use a little mineral spirits. Both of those won't blow up on you, but about any light hydrocarbon does the job, lighter the faster, but lighter the more important you let it sit and not blow your lamp up. Gas, white gas, lighter fluid, things like, that you gotta wait till its all evaporated away, all. Now you know why I use mineral spirits. Its quicker. Its only slightly lighter than kerosene so dissolves gum not the best, but its not explosive, works as a lamp fuel in a pinch, and I can throw the wick right back in a lantern.

Now keep in mind, flow rate is limited by time. For example, as a wick gums, to get that nice even burn with no soot or smell, the flame and amount of light will get less and less, as flow is restricted. What this means is the opposite is also true, you put too much demand on a wick, you can starve it. Obviously if you turn a wick up way too high, you aren't doing a lamp anymore but have a fire on your hands as it burns on the sides and everything else, but there is a zone there if you have too much flame, the wick won't pull fast enough. This is why you have wider wicks for more flame and wicks that are specifically designed for certain fuels.

A lamp that is designed and usually stamped o the bottom, Liquid Parrafin, will gum far faster with kerosene than liquid paraffin. Liquid paraffin is a slightly lower specific gravity than kerosene thus why its recommended you don't use it on kerosene wicks over 7/8". I don't even on 7/8" and that's my favorite fuel for indoors.

Now to take this to conclusion, you can't eliminate bad kerosene as a cause. Keep in mind, kerosene is a hydrocarbon fuel, a mix of chemicals. There's not this one formula that's kerosene. That means its going to vary on what is called kerosene by who you buy it from and when. Also keep in mind, that same distillation process I mentioned about the lamp and kersosene applies to stored kerosene. If its in an open can for too long, it will thicken up on you. Stored in a closed can, it has an amazing life compared to gas but it still has a limit. A good rule of thumb is yellow kerosene, time to use that in your heater and buy some new kerosene for lamp oil.

BTW, All this wick stuff applies to a kerosene heater too. They just have much much bigger wicks so way more room for error but keep one long enough, you'll either be putting new wicks in or doing maintenance on them too.

Usual cause of oil lamps gumming, you didn't run them dry and then let them sit with fuel in the tank over a long period of time. Obviously, it kind of impossible to run these lamps dry every time we use them and because we can't predict when they will sit for a long time, its going to happen to most of us time to time. Our ancestors, well they used the lamps every day so it wasn't quite as much a problem for them. They had fresh fuel going in those tanks regularly.

Tj

I used both of mine the other night around the campfire. Tonight, my brother in law is borrowing them during a power outage. They are the black and brass ones. I could not be happier with them. They are functional and look great.