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hi all!!! I've read that magnesium must be coated with linseed oil or with potassium dichromate.How can I coat my magnesium with linseed oil? I want to do this stars having this formula

Hardt Green Star #5
Barium nitrate 56
Red gum 7
Magnalium -200 mesh 17
PVC 15
Dextrin 5
Can I use magnesium without coating because there is PVC?

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'Magnelium' the chemical used in this formula - wich wouldn't allow replacement with magesium- must not be coated.

Coating magnesium with lineseed oil is a bitch :D.

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sorry I was wrong... I want to do Hardt Green Star #5 with magnalium but this formula with magnesium :
Lancaster Red
Strontium nitrate 55
Magnesium 28
PVC 17
Must I coat magnesium in this formula?200mesh magnesium is useful for metal stars or it is better to use another mesh size?
thanks

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If you wanna bind with water, then you have too coat the magnesium. Its easier to bind replace 10 parts of the PVC for 10 parts parlon and then bind with aceton (dangerous). An other method is adding 5 parts red gum and binding with pure alcohol.
The stars are very bright and nice red.

edit: So you have to coat the magnesium unless you prevent it from contacting water.

Edited by explomaan

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200 mesh will work, but you really need to coat it, if you will not coat it it will react with heat. So thats something you dont want in your flameble starcomp :D.

If you want to coat your Mg you can do all the Mg in a bucket an ad some linseed oil, than shake and ad some more till everything is al littlebit sticky. Than spread it out on some newspaper and let it dry for 5 - 6 days. That will give you a good coating.

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Or you could use phenolic resin as a binder with aceton.

Don't know if it works with aceton, but alcohol is a better option.

1 doesn't disolve plastics (sprayer and drum)
2 evaporates slower.
3 better for your health.

In commercial business redgum is only used as fuel, not as a binder. Edited by ener

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Most aliphatic phenolic resins seem to dissolve in acetone as well as in alcohol.
The reason i like acetone more then alcohol is the availability (I can't buy a ltr of 99% IPA or 96% ethanol at my local shops without ordering first)
And i like the reduced drying time of the stars. (like the parlon based compositions)

But acetone is more flammable then alcohol which could pose a risk when drying..

Edited by azure

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Thats because its easy to dissolve parlon because that can be done with thinner or such. And PVC is really hard to dissolve.

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-If youre PVC powder is really fine, then you can try to bind it with aceton an press stars with a star plate and a press.
or
-You can try to bind the stars with PVC-glue, this option is likely to work. Test first of the pvc glue can be combined with magnesium.
or
-Use another external binder like discussed above.

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I've use both the Barium Nitrate and Strontium Nitrate versions of this star both with fine powder form PVC bound with Acetone, the Acetone dissolves the PVC no problem and makes rock hard stars.
If you do it like that there is no problem with reaction of the Nitrates and the Magnalium and no need to coat the Magnalium with anything. The stars are dry in around an hour and done outside well away from any ignition source and wearing a solvent mask it's pretty safe.
These stars are hard to beat for colour saturation and brightness.

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Bangkokpyro, did you put some of those stars in a shell? Did they survive the break?



Yes sure they survived the break... they are like concrete when dry.
I always use cut stars. Just add enough Acetone to the mixed comp in a stainless steel bowl till it's tacky and like bread dough and knead it together for a minute, roll it to the thickness of the star you want and cut it into cubes with a straight edge sharp knife.
It's important that the PVP is fine mesh.... around 200 mesh or finer or It's not going to bind well and you need to buy your PVC powder already fine as you cannot grind or mill it any finer later. Magnalium for these stars also needs to be very fine 325 to 400 mesh works best.

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The stars contain magnesium, and no magnalium:
Lancaster Red
Strontium nitrate 55
Magnesium 28
PVC 17

I will try to bind PVC with aceton.

Edited by explomaan

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I tried this last week, just to see how the binders work.
Parlon bound with Acetone worked great, nice rockhard stars in no-time.
PVC bound with Acetone didnt even get sticky. Even using high grade PVC it didnt even get sticky, let alone hard. Then worked it all into a slurry and let that dry a bit. Still just as crumbly as before. No use.
PVC bound with MEK worked a little bit. Though a lot of solvent was needed and stars kept cracking. Either when coming out of the starpump or when drying.
When a MEK bound PVC star was lit it exploded on ignition, due to cracks in the star.

Anyone knows a easily available PVC solvent? Because THF is not readily available to me for any reasonable price

*edit* Sorry, no pics or vids available *edit*

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