Glass candle broke near bottom

[karinz40]

A friend learning to make candles, not a close friend, gave me a candle as a gift.

I havebeen burning it every few days and was near the bottome when the glas  broke.  I am assuming it as because the candle was to hot.

The cent had been nice and she said the ax was paraffin when I asked her.

I do not want to hurt her feeling  and tell her yet that it broke untill I understand why.

Any help would be appreciated.

It was n 8 oz mason jar with 4630 she said.  The same ax I am experimenting with but not in glass

that is exactly hy i am not using glass.  That and shipping

[TallTayl]

Scary!
 

Did you happen to get a temp as it was burning? 
 

it could have experienced thermal shock if it were burning hot, and on a cold surface. 

[bfroberts]

Is it possible she used a repurposed jar or it was damaged prior to burning the candle?  
Mason jars can withstand a lot of heat.  Was the candle over-wicked or overly hot when you were burning it?

 

ETA:  LOL...TT beat me by seconds.

Edited September 11, 2020 by bfroberts

[karinz40]

it was on my credenza in dining room, glass top.

She was making candles with mason jarsfrom wall mart new.

I did notget temp

Probably wick a little to  big?/  Flame was ok  I think.  i don't burn candle from glass, just my tins but because she gaveit tome I thought I would.

[TallTayl]

I would be inclined to let the maker know.  Things could have gone quite bad. Luckily it sounds like you were watching it and a) were not injured by the force of glass breaking or b) victim of a fire from the break. Count all of your blessings today. 

[karinz40]

I am going to let her know

That is why i do not like glass candles and am sticking to tins.

[Candybee]

Your friend may also want to know how long you were burning the candle or how long it had been burning when it finally broke. Also, I know its too late now but it would have helped to check the surface of the glass top of the credenza to see if it was retaining heat from the candle as it burned. I know it sounds crazy but different surfaces and the surround can make a huge difference when burning a candle. A candle can catch fire for example if you place it on a windowsill next the the window glass. 

[coconut]

As TallTayl said, it was likely thermal shock. This can happen if the flame burns too low in the jar. One way I found to prevent this was to use a wick tab with a tall neck. That way the flame will usually self extinguish before it burns down to the glass. I used to deliberately burn mine to the bottom to test this. I have had canning jars break around the bottom when my jar  cooled slightly and then put it in the boiling water bath. Definitely tell your friend. That is what testing is about.

[CandleRush]

Do all wicks have tall necks or is this something you put onto wicks?

[TallTayl]

1 hour ago, CandleRush said:

Do all wicks have tall necks or is this something you put onto wicks?

Retail available wick tabs come in at least 3 neck heights. Commonly offered retail are 3mm, 6 mm and 9mm. 3 is super short.
 

https://www.candlewic.com/store/category.aspx?q=c41&title=Sustainer-Candle-Bases-(Wick-Tabs)

https://www.precisionwicking.com/hob/

 

9 is noticeably  taller than candle science for instance. lone star tabs common sizes for containers with 10mm 

https://www.lonestarcandlesupply.com/eco-10-6-wick.html

 

 I see 6mm most often on pretabbed wicks. Like at Candlescience for instance. https://www.candlescience.com/wick/cd-6
 

when you go to taller necks, prepare for customers to complain about “wasted” wax. For some reason it is a “bad” thing to have even small amounts of wax left in the jars, even if it is for safety.

[karinz40]

Thanks,  did not know about the necks