Science Buddies: "Ask an Expert"

I'm trying to test how different types of candles burn. I understand that I need to test them in controlled environment/draft-free, etc. Do you have any ideas on what I can test them in? Do you suggest a glass fish tank?
Thank you.

jw55nets wrote:I'm trying to test how different types of candles burn. I understand that I need to test them in controlled environment/draft-free, etc. Do you have any ideas on what I can test them in? Do you suggest a glass fish tank?
Thank you.

First, you will always have drafts. The candle itself will create drafts. You want to minimimize external drafts (that will blow-out the candle) or creating a situation where the draft created by the candle is very turbulent. I will talk about this a bit more below.

I actually think a closed or semi-closed container might cause more problems. I'm not sure exactly what you want to test, but usually candle makers test burn rates over 2-3 burn cycles of 4 hours each. (They use weight of candle before and after burn to determine the amount of candle burned). In a fish tank, you have a pretty small volume of air. If it is closed, you might exhaust all the oxygen and the candle will go out.

If it is open, I imagine you will still get drafts... the air inside will warm from the candle and then rise up. Colder air wil drop down. If you look enclosures that are described as protecting a candle from a draft ( such as hurricane lamps for example) they are actually designed as a chimney. There is a draft, it is just controlled in a way to help candle burn.

The great thing about this project is the candle smoke can tell you if you have draft/convection problems. I'd test in a few places and look for the smoke going straight up, and staying tight in a stream for as long as possible. This is checking that there are no external drafts and that there is nothing chaotic about the draft created by the candle. (Use the same type of candle, as the burn properties of the candle could effect this). If the smoke leans or swirls a lot, then try a different place. (And document all this- this will help show you've found a controlled environment)

Hope this helps you some. Post back here if you have more questions.
Louise

The problem is that I have air conditioning vents all over the place and I can't block them or turn them off so that's why I need some sort of closed box to prevent the drafts. what do you think I should use?

jw55nets wrote:The problem is that I have air conditioning vents all over the place and I can't block them or turn them off so that's why I need some sort of closed box to prevent the drafts. what do you think I should use?

I see. There are glass covers for candles that look like a cylinder or a wavy cylinder. Do you have one of these?

You cannot use a closed box at all, I think. It will have to be open.

Louise

Thanks for the quick response! Do you know what type of stores would sell these glass covers?

jw55nets wrote:Thanks for the quick response! Do you know what type of stores would sell these glass covers?

Probably someplace like Pier 1, Home Depot, or any stores that sells decorating stuff for the house. For example, at target.com, searching for "hurricane candle" returns a bunch of choices (Fall Clear Hurricane Candleholder looks good). Actually, if you had a really big jar, with the top very large, this might work too. You want something tall (taller than your candle) and probably 3-6 inches in diameter at the top for a standard taper candle. If you are testing small candles (like votive candles) then maybe a drinking glass would be fine.


Louise

Thank you so much, you were such a help!

jw55nets wrote:Thank you so much, you were such a help!

No problem. Check the tests I suggested though (looking for straight smoke, trying a few spots), to make sure you have found the best place.

Good luck with your project.

Louise