Gather up as many old candles as you can spare and place then in a large ziplock or plastic bag.
Using a hammer and medium force, break the candles into smaller pieces. Remove the remainder of the wick and extraneous paper or metal before continuing.
Place the plastic bag filled with the broken candle pieces on a food scale and note the weight in ounces. Write this number down for future reference.
Heat an old saucepan on a hot plate or stove top. Add the broken candle pieces to the warm saucepan and increase the heat until the candle pieces start to melt. Continue to mix in pieces of broken candle until all are melted.
Place the glass jar on the food scale and pour in enough paint thinner to equal one-fourth of the weight of the broken candles. For example, if the candles weigh 8 ounces, pour in 2 ounces of paint thinner. Remove the jar from the scale.
Pour melted wax into the glass jar with the paint thinner. Screw the lid on the jar and shake gently to mix and blend the wax and paint thinner. Your green wood sealer is now ready to apply with a brush, or simply dip small pieces into the glass jar.