only connect Posted October 17, 2010 Share Posted October 17, 2010 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? Link to comment
danny db Posted October 17, 2010 Share Posted October 17, 2010 '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 . Link to comment
only connect Posted October 18, 2010 Author Share Posted October 18, 2010 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 Link to comment
explomaan Posted October 18, 2010 Share Posted October 18, 2010 (edited) 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 October 18, 2010 by explomaan Link to comment
Weirdo Posted October 18, 2010 Share Posted October 18, 2010 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 . 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. Link to comment
azure Posted October 19, 2010 Share Posted October 19, 2010 Or you could use phenolic resin as a binder with aceton. Link to comment
ener Posted October 19, 2010 Share Posted October 19, 2010 (edited) 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 October 19, 2010 by ener Link to comment
azure Posted October 19, 2010 Share Posted October 19, 2010 (edited) 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 October 19, 2010 by azure Link to comment
only connect Posted October 23, 2010 Author Share Posted October 23, 2010 Hi explomaan! why I must replace PVC with PARLON? I have very very much pvc powder but any parlon powder ! thanks to all for the reply!!!! Link to comment
Weirdo Posted October 23, 2010 Share Posted October 23, 2010 Thats because its easy to dissolve parlon because that can be done with thinner or such. And PVC is really hard to dissolve. Link to comment
only connect Posted October 23, 2010 Author Share Posted October 23, 2010 shit! so, how can I make stars with this composition using PVC like that formula? Link to comment
explomaan Posted October 23, 2010 Share Posted October 23, 2010 -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. Link to comment
bangkokpyro Posted October 28, 2010 Share Posted October 28, 2010 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. Link to comment
explomaan Posted October 28, 2010 Share Posted October 28, 2010 Very interesting, can someone verify that you indeed can bind PVC powder with aceton? Link to comment
ExplosiveCoek Posted October 28, 2010 Share Posted October 28, 2010 Bangkokpyro, did you put some of those stars in a shell? Did they survive the break? Link to comment
bangkokpyro Posted October 29, 2010 Share Posted October 29, 2010 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. Link to comment
explomaan Posted October 30, 2010 Share Posted October 30, 2010 (edited) 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 October 30, 2010 by explomaan Link to comment
only connect Posted November 3, 2010 Author Share Posted November 3, 2010 If I use MEK to solve PVC?? Link to comment
Tyneman Posted November 3, 2010 Share Posted November 3, 2010 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* Link to comment
only connect Posted November 3, 2010 Author Share Posted November 3, 2010 I have at home PVC k65. I tried to solve it with acetone, kerosene and turpentine without result :( Link to comment
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