gerbs

[shadowpatterns]

Hello all. A newbie here. I want to make a fountain and have read that BP itself does not get hot enough to ignite the colorants. So, do I use Potassium perchlorate in place of KNo3? Just want to make something pretty and zero casualities. Also, what kind of strontiom is suggested? Thanks all. SP.

[nater]

I don't understand what you mean by "BP won't light the colorants" A BP gerb will burn more or less orange and you can get sparks with different metals. If you want a colored flame, you can pick different comps for the color. If you want colors in the plume, then it is usually done by mixing colored microstars in with the fountain comp.

 

By asking what kind of strontium to use, I am assuming you want to make a red gerb. Go to Skylighter.com and look for the "plasma cutter fountain" project and follow it. http://www.skylighte...er-fountain.asp The red is based off a gerb comp from John Glasswick.

 

Red Gum - 10

Parlon - 20

Magnalium - 20

Titanium - 15

Strontium Nitrate - 50

 

I have rammed these, using light taps with a small mallet, nowhere near as hard as you would pound a nail. I feel better pressing them due to the metal. I have use commercial gerb tooling. The first increment after the nozzle is BP. I usually use my rocket fuel because it is handy, the second increment is 50/50 BP and the above comp without the tiatanium. I leave the ti out to avoid pressing it around my gerb spindle, just in case the first increment does not clear it. Then, I press the increments of gerb comp with the ti, and finish with an increment of clay.

 

Here is a completed gerb, that burned too long.

 

Edited July 29, 2012 by nater

[Seymour]

Typo, it's 50% Strontium nitrate in John Glasswick's mix, not 20%. I also suggest pressing these high metal mixes.

 

Black Powder actually does burn hot enough for colours. Admittedly while some colourants and chlorine donors will lower the temperature, this can be increased to some extent with changes to the fuels and ratios, for example, adding MgAl. By all accounts I've come across, and my experience, they are pretty uninspiring and really washed out.

 

Potassium perchlorate is very common as the oxidiser in colours, though as the composition posted by Nater shows, it's not always the case. For Red (and purples, oranges and yellows) Strontium nitrate is often used, and the same with Barium nitrate for Green (and yellows, green-blue range). Here the nitrate is the oxidiser and colourant. If you were to use the carbonates, an oxidiser needs to be added, commonly Potassium perchlorate.

 

For example, here is a slight modification of Buell Red (rounded to whole percentages)

 

Potassium Perchlorate 35

Strontium Carbonate 25

Magnalium 14

Parlon 13

Red gum 7

Dextrin 6

 

Titanium can be added for sparks, or Iron, FeTi, ect.

 

The Mgal in both of these mixes is not intended to be for sparks but just to aid in getting a good hot and bright flame.

 

In all these mixes the parlon is very important, as it supplies all the chlorine needed for making the chlorides that emit at the right wavelengths. While Parlon is not special in this regard, as other sources of free chlorine can play this role, the role is very important, and for Green, Purple and Blue, just as important as the colourant salt(s).

Edited July 29, 2012 by Seymour

[nater]

Typo, it's 50% Strontium nitrate in John Glasswick's mix, not 20%. I also suggest pressing these high metal mixes.

 

 

Corrected, thank you for catching that.

[shadowpatterns]

Thank you guys for the information. Exactly the kind of knowledge I need to get started!.

[ChrisT1985]

I've been playing with red and green gerbs from the skylighter page recently and I don't think it is that the gerbs are burning too long. The red seems to be burning through the tube, because there is not enough fuel. Try this comp below instead, it burns for ages with no tube burn through, and no orange flame after the comp has been consumed. The orange flame is coming from the casing still being on fire, after the comp is done. This is the comp I ended up using to fix it, the tube was 1/2 inch X 4 inch and it used 1/3 nozzle :-

 

Strontium nitrate----------38

parlon----------------------17

magnalium-----------------17

titanium--------------------13

red gum--------------------10

charcoal--------------------5

 

I will note though that the green performed pretty well with the original red comp, even though it also is seeing a touch too much oxygen. This was what made me think, because I tried them all red green and yellow. They performed in order of their oxygen content, barium has least oxygen and performed the best. Sodium was clearly worse for burn through, than the strontium was too. The yellow I'm struggling with, but I think it's more due to the hygroscopic nature of the sodium nitrate. I was going to change it to barium nitrate/potassium perchlorate/sodium oxalate and give that a go for the yellow.

[Mumbles]

A blend of barium nitrate and strontium nitrate (being green and red), can be blended to make all shades of yellows and oranges. I find about 60:40 barium to strontium is a nice yellow starting point. Plus, you aren't restricted to only sodium or calcium yellows and oranges. It's probably just engrained in my mind as impurity colors, but I don't care for either of those particular hues.

[schroedinger]

If you're new to this, the easiest thing for you would be to make some smaller fountains to get some feeling on how the compositions behave,best star by building some 15mm Tubes with TT and D1 composition pressed in. Build a clayhead and drill a hole like 3-4mm trough it, with just touches the fuel. Ignite with visco/bp

[ChrisT1985]

hey mumbles I was aware of the barium and strontium mixing to make yellow or orange, but I was wanting to do it without using them mixed. I was going to save that option for last resort, I think oxalate will work out a bit cheaper than using the nitrates to get the yellow. I may end up using it though, If I don't manage to sort a reasonable oxalate comp... oh, and thanks for the tip. Edited August 31, 2013 by ChrisT1985

[Col]

Using nitrates cuts down on the chemical inventory and saves time, mix 2 comps and get a choice of 4 colours. Its actually a pretty good yellow...if you like yellow that is

http://youtu.be/oL914kpVqqw

[FlaMtnBkr]

Were those oxy/acetylene hoses running right next to the star burn test? Hard to tell but it almost looked like it was indoors.

 

Guess I'm on a safety kick here lately.

[Col]

Garden hoses, its definitely not indoors with the wheelbarrow in the background

[FlaMtnBkr]

Just checking. I have oxy/acetylene hoses that look very similar and also have a wheelbarrow inside my shop.

 

I fiured it was most likely safe but just wanted to make sure.

 

I still want to compare some yellows made from red/green compared to sodium yellow. A nice bright lemon yellow sounds nice but just not something I have gotten to yet, like so many other projects. There are also some great orange colors I have seen that I would like to perfect.

 

And a calcium flame test is really beautiful though I'm not sure I have seen that color in pyro. Anyways, I'm rambling. Thanks for letting me know you were being safe!

[ollie1016]

A nice little composition I 'made/ discovered' was

MgAl 250# 35%

Sulphur 40%

Meal powder 20%

Ferro titanium 5%

 

This can be very hard to ignite, so I recommend using a higher % of BP in the top of the gerb. Once it gets going, it's fine. This burns very hot and quite slow( BP variables). It is extremely bright, and my 6" long 3/4" ID tube was all done in 25~ seconds.

 

To prepare, screen all the ingredients together using a 50# screen if you have one. (20# will do too). Then put them in a plastic box, and give it a good shake. Then ram into your desired tube as you would for a solid grain rocket. I like a 1/4" nozzle on mine, but you'll need to experiment.

 

Ollie

 

EDIT: By the way, DON'T BREATHE THE SMOKE IN! I've been told it has sulphur dioxide in it which is harmful to us! You will cough and have breathing difficulties if you breathe in larges amounts.

Edited September 9, 2013 by ollie1016