It’s probably easier to get a new set, every 2 years.
Try soaking in baking soda/ water mix. Let sit over night
Put your oil glasses in a large washing cup filled with water and let it sit in the water for a few hours and then take them out and hard wipe each one until their dry and ready to be put away
Each glass costs 50 cents?
Get a FULL set of glasses new for less then 50 cents each
A little bit of dishwashing soap like Gila and light steel wool and warm water will do the trick
I’m surprised so many of you are suggesting they simply be discarded because they’re cheap. פחים קטנים and all that …
They say fight fire with fire so add some burn stains and maybe they’ll all go away
What kind of wick/supports do you use? I use the metal tubes with a base that keep the wick in the center of the glass and have never had problems with burn stains at all. Also, don’t put a layer of water under the oil as the sputtering also causes stains. And floating wicks especially are a recipe for disaster.