Introduction: Etching Waste Green/blue Candle

About: I work in optical design.

This instructable shows the use of Copper Chloride as a fire colourant and the production of a small candle which can be used with a standard candle holder.

First of all, let me adress the fact that this, like most coloured fires, involves some chemicals that are not very good for the enviroment. So only small quantities were used (and only small quantities are needed, it's quite strong stuff)

That said the substances used are not thát dangerous or poisonous. More like a 'maybe-you-should-wear-gloves' or a 'try-not-to-get-it-in-your-eyes' kind of poisonous.
The main problem is that they are quite corrosive. (see later)

I know green fire has been done before, but mostly with Heet and Boric acid. Not much people have used Copper Chloride. Besides, it is mainly blue fire (see last step).

This instructable is mainly a response to The Green Gentleman's   'Spirit Lantern'  since it provides an alternative fuel that doesn't produce the white smoke that settles onto everything.
I made the candle with a test tube so it fits in a candle holder, but of course it can be used in his lantern. However, the main additives and combustion products are a bit corrosive and that perhaps requires some modifications.

And perhapse also a response to The Real Elliot 's 'Better etching solution' instructable since this is the etching method I used.
However it is not a way of getting rid of the waste. Since I used very, very small quantities.

Besides some complications and restrictions because of the corrosivity it is pretty basic and the result is a nice colourful flame.

Step 1: Parts and Tools

This is a list of all things used for the candle. Everything can be switched by other things but try to avoid reactive metals such as aluminium.
Note that this was just some personal entertainment, I did not measure much. The quantities of the Copper chloride are so small that it is no use of measuring them with a kitchen scale.

At the bottom are some comments on the chemicals involved.


    A small test tube. 
    (Probably not a real one, it came with some advertisement I think. But the flat bottom is great and it fits in a candle holder)

    The lid of a jar.

    Some thick copper electrical wire. (I used 1.3 mm)

    A bolt (see later, it must just be something cylindrical)

    An old cotton rag.

    Maybe some string.

Tools used:

    Small pliers

    Tin snips

    Old dull X-acto knife

    2 small files

    A piece of sand paper

    A nail (4 mm thick)

For the fuel.

    I used 85% ethanol (alcohol)

    CuCl2 / CuCl  (the etching waste basicly,  not much is needed, I think I didn't use more than 1/10 th of a gram for this entire instructable. (except in the next step of course) )

The main components are CuCl , CuCl2 and methanol.  And since you burn them together with alcohol, you get mainly HCl and some HOCl as the main combustion products (besides the normal ones COand H2O). And some Cu, but most of that stays on the wick. Yes, these are a bit corrosive but in small quantities they don't do very much.
Don't burn this candle in a small room or area.

Also, those CuCl , CuCl2 like attacking other metals. Try to avoid contact from e.g. Iron with the solution. Also keep it away from alluminium it just gets eaten.
Just type it in google, it is quite interesting stuff.

Basicly think 'fungicide' for the copper compounds (because they are (sort of) ) and treat them as a 'cide' and you'll be fine.

HCl is HCl, just don't breath that in too much.  (think puke, it smells anyway)
HOCl look at wikipedia, it pretty much decays into H2O andn ClJust don't breath that in too. (think bleach)

Step 2: The Copper Chloride

So, last summer I tried etching some pcbs with Copper Chloride. The way Mr Real Elliot explained it, because this in way is that you can produce it in small quantities which is great for just trying it out. (the Ferrous Chloride comes in bags of 2 kg in a shop nearby)
It never really worked for me because I probably did something wrong with the photoresist.

But this copper chloride is very potent stuff. It just ate away all the copper.

But anyway. After that, it was just standing there for a long time. And I once read that Copper(I) Chloride (the reacted product of this etchant) was used as a pyrotechnic colorant, so I had to try it out. I kept adding copper wire in order to maximise the amount of Copper(I)Chloride. But the etchant was constantly regenerating (to Copper(II)Chloride)  with the atmosphere and the copper slowly kept dissolving. (It is actually very surprising how much copper ~2 dL of this stuff could eat. ) The liquid became very heavy and blue.
I dried some of it, and in fact yes, a sniff of those crystals onto a fire turns the fire into a bright blue.

Then later I saw The Green Gentleman's candle and thought, this blue fire would fit well inside this lantern. 

So basicly what you have to do for this is to follow Mr Real Elliot's instructions (for a small amount of liquid a couple of tens of cL is perhaps enough) keep adding more and more copper till it takes days to dissolve. Keep the lid open so it can regenerate with oxygen from the atmosphere. Perhaps keep it outside because some of the HCL likes to evaporate and it smells.  (in my case a lot of snow fell in, so it was somewhat dilluted)

The solution should be thick, blue and heavy.
It now should be a mixture of dissolved Copper(II)Chloride and Copper(I)Chloride. I don't think it is possible or easy to turn all of it in Copper(I) Chloride.   There also will be impurities due to other metals depending on the the copper alloys you have used and of course the amount of bugs that managed to get in.  So this is in no way a precise project.

Then simply evaporate it out and collect the crystals. (see the pictures)
But know this isn't the most pedagogical substance because it constantly changes colour depending on the concentration in the liquid or amount of moisture in the crystals.  It ranges from blue green, yellowish green to brown in it's dehydrated form. Pure Copper(I)Chloride should be colourless.

Also, notice that I placed a copper wire inside of the liquid this was an effort to again minimise the amount of Copper(II)Chloride. Again with all the contact to the air the liquid regenerated a bit again and started eating the wire.  However it was only a very small amount yet it is visually very dramatic since it turns the liquid very dark brown.  This doesn't do anything with the substance, they will turn green later on.

This evaporated out in the sun on the roof and the sides touching the hot black metal were so hot they dehydrated and became brown. This brown has nothing to do with the previous brown.  After a couple of minutes inside they were green again.
The end result should be bright blue /green crystals.  (Ideally it should be colourless)

Again, the pictures show way too large quantities! Only a very small fraction of this is needed.

Step 3: The Candle Top

As mentioned in the part list, the holder of the liquid is just a glass test tube.
I don't know if it is a real one out of pyrex. It just came with some advertisment (I don't know about what anymore).

But anyway, this tube is the most convenient small glass flask available. The small jars are occupied.

As you can see, the tube is sealed with a cork which is pretty useless and it does not have a screw-on cap.
So, some sort of cap is required to hold a wick.

For this cap the lid of a pickeled onion jar is used.
A square is cut out of the middle.
Onto this square the test tube is placed and with a pencil the contours of the tube are traced. A Union-Jack-ish pattern is added, these will be the extensions grabbing on to the tube preventing the cap from sliding off easily.
I did not measure anything, perhaps it would look a bit tidier but I mainly wanted to test this out.

The pattern is cut out with tin snips and the extensions are trimmed to an equal size. The corners of those extensions are trimmed because they will be bent inwards so they won't be in each other's way.

The sides are filed off a bit to reduce the sharpness and serratedness.  Then the red and grey paint coating is removed with some sand paper exposing the bare metal.  (But maybe it isn't a bad Idea to leave it on, because of the corrosiveness of the CuCl)

The tips of the extensions are bent inward a bit. After that, the complete extensions are bent in so that they look like arms that grab on the test tube.

Notice that this isn't airtight. Surely a flask with a screw on cap is way better. The alcohol will evaporate and come out the wrong places causing a flame that is a bit too large.

Step 4: The Wick Holder and the Wick

So, this candle works via the principle of an oil candle.
The test tube is a container for a flammable liquid (in this case 85% alcohol, there are probably better substances). The flammable liquid travels up the wick by capillary action. Where it then is exposed to the flame and air.

A hole is cut in the cap trough which the wick will be inserted.  The hole is made using an old, dull (already broken) X-acto knife and a nail because I don't have a drill and it is the easiest way to cut trough the cap without damaging the extensions.

The first thing I tried was simply putting a wick trough that hole and lighting it.
This had two problems. First I tried it with the 85% alcohol and the fire was too wild. The cap heated up which evaporated more alcohol resulting in a bigger flame. This was not good for a candle. Then I added some water with dissolved Copper Chloride.  Hoping this would result in a cooler flame which it did. However, it was per haps too much water because the wick barely lit anymore. The second problem was severe corrosion of the iron cap where there was contact with the wick.  Namely the iron was reacting and replacing copper in the solution. So, it is clear that this would not work.

So, the flame must be removed at bit from the container containing all the alcohol AND contact from iron with the wik must be reduced.
The solution was putting a copper tube trough the cap trough which the wick went.  The tube extends a bit thus increasing the distance of the flame. Secondly since it is copper, it barely interacts with the solution in the wick. (And if it does, it doesn't matter).

However, since I did not find a copper tube this small, some coppr wire was wound up around the nail. 9 turns.
The hole in the cap is increased so that the copper spiral just fits.  1-2 turns are inserted into the cap, the rest stick out.
Try to do this as precise as possible.

As a wick, a piece of cotton cloth is used from about 2 x 6 cm.  In one end, this wick is wound up tightly and pushed trough the copper spiral tube.
The other end is wound loosely around the other non- trimmed end of the copper wire so it can fastly be inserted into the test tube.

A small amount of copper chloride powder is put in the tube, some water is added.  (how much depends on the flame you want, but I don't know what's the best ratio alcohol/Water/Copper Chloride. )
Put some Copper chloride powder on the tip of the wick, it helps.
Then add some alcohol, put on the cap, wait till the fluid reaches the top and then light it.


It still is not stable enough, the main problem is perhaps the non-air tightness of the cap.  And the copper spiral. The flame still likes to creep down slowly along the spiral.  This increases the size of the flame till it is a bit unconfortably large.

The solution is to close the gaps.  I have simply put a nut around the copper spiral and it worked great.
After playing and moisturizing the wick with alchohol, the flame stayed stable and of a constant size till only about 20% fuel was left.

Next step will include pictures of the unstable candle version.  (I used one of these as the thumbnail picture because it is in my opinion more beautiful with the copper spiral)

The step after that contains pictures of the stable version with the nut.
And actually the flame there was as expected. It is not very visible on camera but the candle was very bright blue.

Step 5: The Unstable Candle

So, these are pictures of the unstable version of the candle burning.

As said before, this flame starts good, but tends to grow, a bit greenish thoug.  As the metal of the candle heats up, it probably evaporates more of the alcohol which leaks trough openings of the spiralled copper.
I had to do this more precisely, or had to use a piece of tubing.

After about 30 seconds of fire, it begins to grow slowly. It also starts making noises. Notice that some of them are small and some of them are bigger. And notice that the bottom of the flame creeps down along the copper spiral.
And it starts making noises when the flame becomes too big.

The camera picks the flame up very different depending on the lighting time and apperture.  (I have taken the moving image setting, so the camera does whatever it thinks is best.)
But if you look at the photos, mind that the vaguest flames are visually a bit brighter. And the brightest ones are a bit too bright.
The medium ones are about what you see.

Also, note that the flames are mostly green compared to the ones in the next step which are mostly blue.

Step 6: The Stable Candle

As you can see, this is the same candle but simply with a nut around the copper spiral.
Notice that the flame is much bluer than the one in the previous step.

This results in flame with a very bright blue spot.  This is actually very colourfull. The bottom part is dark blue (the ususal alcohol type blue) then higher up, small green flashes occur as if small particles shoot up and ignite at a certain hight. Still higher up, there is a very bright blue flame.  Perhaps not as bright as in the photos, but still quite bright. 

Interestingly if the wick is still a bit higher, the flame goes over into purple.

The candle only burns about 3-4 minutes. (very small quantities)

So, yes, very interesting candle. Just don't do it too much. And keep the quantities small.

Please do tell me if I made some mistakes, English language errors or if I missed out something important.