Coating Mg

[al93535]

Cyclohexanone will dissolve both PVC and saran resin.

 

PVC makes quite a good binder, and has good adhesive properties. It was sticky on my gloves and held its own after it dried. It may work to coat Magnesium.

 

Saran had almost zero adhesiveness to it as the solvent was evaporating, it then rolled off of my glove. I suspect it would be a bad binder, and would come off the mag too easily to be useful.

 

But then we would need to test both to be sure!

 

Parlon is a proven excellent binder, and coats magnesium very effectively. Why not just use it?

[Twotails]

Well, back from testing, and it seems that the Saran does indeed protect the Mg, But ony to an extent. I did two tests, side by side, same formula with the exeption of one having 33.3g coated Mg, and the other 33.3g uncoated.

 

the results:

 

the uncoated foamed up when it was perpously over wetted(just a slight bit, to provide a worse-case scinario) and smelled like ammonia.

 

The coated dident foam, but there was still a very slight ammonia smell, but almost not noticable(Unless of corse you place a sample direcly under your nose, and knew what you should expect, almost no smell other than the Red gum)

 

 

I would not suggest useing Saran untill i can get a better solvent, and try again and record results.

 

Next is to see if theres any diffrence in star performance.

[NightHawkInLight]

Testing with what oxidizer?

[al93535]

What solvent did you use Twotails??

[Twotails]

At first, Acetone, then reading the posts, used MEK(Amazing what you find in your garage here i was looking for it in stores, and my dad had some in his plumbing/paint supplys!) and i tested it with a AP based comp.

 

Also, I have the chance to bye some Xylene for $10 from a friend, its 1 pint. Think i should buy it? would that desolve the Saran better?(me thinks so...)

[QED4803]

Thanks a million for all the help al, et al. Just got around to coating my Mg today as the weather has been nasty. All seemed to go swimmingly with the proportions you recommended. I'm itching to slap together some metal-fueled stars!

[PoorBoy]

I'm trying to understand reactions with Mg, and it seems to get more confusing as I read. I read and understand the coating processes, but not what they protect the Mg from. What i understand thus far is, Mg + Nitrates = Bad (but is that only when mixed with water, what about if i use red gum/alchohol). From this thread I learned AP + Mg = Bad (once again in the presence of water or alchohol or just in general). I have K Dichromate, and could probably find linseed oil. I think I'm gonna use the dichromate just because it sounds easier. I just don't understand what it needs protecting from other than what I mentioned, and I'm not 100% sure what the Dichromate coating qualifies to protect it from. This is more agrivating than the time I tried to make Cut Yellow stars with about 75% dextrin and too much water...

 

 

[al93535]

Potassium dichromate treated magnesium will be safe to use with ammonium perchlorate. This coating is the ONLY effective treatment for magnesium when using AP.

 

Linseed oil treated magnesium will be safe to use with all other oxidizers.

 

The best idea is to never use aqueous binders. The use of dried solvents and parlon is extremely effective and highly reccomended. This way you dont need to treat the magenesium because it will be treated when you mix your comp and wet it with the proper dried solvent!

[Cookieman]

As for coating Magnesium with saran: What available solvents do you have to dissolve the saran resin? Acetone doesn't do it... There are a few specialty solvents that will, but they are not available at the hardware store.

 

 

If you are coating MG for use with anything but AP use linseed oil. If you are coating MG for use with AP use dicromate!

 

from shimizu (which is how I do it except without heating the magnesium) Always works excellent:

 

Coating with potassium bichromate is carried out as follows:

50 grams of potassium bichromate is dissolved in 300cc of hot water.

1000 grams of magnesium powder is heated to about 100°C in an air oven

for one hour. It is placed in a large aluminium bowl and the hot solution

of potassium bichromate is added to it. It is quickly mixed stirring

by hand with gloves until the powder colours uniformly brown. Then the

powder is spread on a kraft paper and dried well in the sun. When dried.,

it is passed through a 30 mesh sieve. The dust must not be inhaled

because potassium bichromate is poisonous.

 

I just coated Magnesium the same method as you described. The general amount of dichcromate to coat Magnesium is 5% of the weight of the Magnesium to be coated. While slightly damp I passed it through a 50 mesh screen to remove some of the clumps, then I let it dry in the sun for 2 days and passed it through the screen again. A word of caution, use a good respirator and heat resistent gloves when adding and mixing the dichromate solution to the magnesium.