Jump to content


Photo
- - - - -

Coating Mg


  • Please log in to reply
33 replies to this topic

#1 TrueBluePyro

TrueBluePyro

    Pyrotechnician

  • Donator
  • PipPipPipPip
  • 437 posts
  • Gender:Male
  • Location:Australia

Posted 19 August 2009 - 09:22 PM

I'm about to buy some Mg and Im wanting to coat it with linseed oil. I dont really like the idea of Potassium Dichromate and I wouldnt need to use it as I wont be using any AP and when using linseed oil, the only thing it cant protect the Mg from is AP.

There are those who dream and those who do, who are you?

http://www.truebluepyro.com ...Go on, Click it, you know you want to.
If you see me running,
try to keep up!


#2 Bonny

Bonny

    Firebreather

  • Donator
  • PipPipPipPipPip
  • 1,232 posts
  • Gender:Male
  • Location:Land of Ice and Snow

Posted 20 August 2009 - 07:42 AM

I'm about to buy some Mg and Im wanting to coat it with linseed oil. I dont really like the idea of Potassium Dichromate and I wouldnt need to use it as I wont be using any AP and when using linseed oil, the only thing it cant protect the Mg from is AP.


I think you use 2-5% linseed oil (IIRC). Heat the Mg in a pan add the linseed oil and keep stirring to stop it from clumping. Allow to cool and run througha screen (again to break up the lumps). Spread it out on some newspaper and let it "dry" for a week or so to allow the linseed oil to plasticize.

#3 TrueBluePyro

TrueBluePyro

    Pyrotechnician

  • Donator
  • PipPipPipPip
  • 437 posts
  • Gender:Male
  • Location:Australia

Posted 20 August 2009 - 11:19 PM

And how would you go about coating it with Potassium Dichromate, I hear it is a little easyer to coat the Mg and easyer to work with.

There are those who dream and those who do, who are you?

http://www.truebluepyro.com ...Go on, Click it, you know you want to.
If you see me running,
try to keep up!


#4 Arthur

Arthur

    Firebreather

  • HE Qualified
  • PipPipPipPipPip
  • 3,268 posts

Posted 21 August 2009 - 12:39 AM

Dissolve the dichromate in water and spoon the metal in! the colour of the dichromate should fade as the surface of the metal reacts and forms the passivating layer. Filter the metal out rinse and dry carefully. (You wouldn't be interested if it wasn't a flammable metal!)

#5 TrueBluePyro

TrueBluePyro

    Pyrotechnician

  • Donator
  • PipPipPipPip
  • 437 posts
  • Gender:Male
  • Location:Australia

Posted 21 August 2009 - 04:09 PM

cool, I have read up on the passfire arcticle as well, but is it easyer to work with? once it has the dichromate on it, you would have to be careful not to touch and wear a mask when useing the Mg?

There are those who dream and those who do, who are you?

http://www.truebluepyro.com ...Go on, Click it, you know you want to.
If you see me running,
try to keep up!


#6 Mumbles

Mumbles

    Grandmaster

  • Admin
  • PipPipPipPipPipPipPipPipPipPip
  • 11,628 posts
  • Gender:Male
  • Location:Above You

Posted 21 August 2009 - 08:13 PM

I am more a fan of the passfire method of coating, which comes directly from Shimizu (more or less). I'm not sure where the soaking in excess of room temp solution came about from, but it raises the problem of excess depleted dichromate hanging around.

Neither method makes the Mg any easier or difficult to deal with. You should be using a mask when dealing with these fine of chemicals anyway. I always wear gloves when working with dry powders as well, so coated or not, Mg gets treated the same by me.
Just so you guys quit asking, here is the link to the old forum. http://www.xsorbit2....forum/index.cgi

The sky is my canvas, and I have 2,113 pounds of powdered paint in the workshop.

#7 al93535

al93535

    MODERATOR

  • Moderator
  • PipPipPipPip
  • 435 posts
  • Gender:Male
  • Location:Montana
  • Interests:Pyrotechnics

Posted 22 August 2009 - 09:08 PM

To coat your magnesium properly and entirely I would advise the use of a solvent to thin the boiled linseed oil. 2% by weight of linseed oil will never fully coat all the mag without thinning it first. I would use lacquer thinner or some other suitable solvent. Acetone might work well but may dry too fast. Just make sure to completely coat the mix by gloved hands. I don't remember what solvent I used, I coated enough mag to last quite some time. I never heated my magnesium when coating it with linseed oil... I don't see the point. When the coated magnesium is set aside to dry spread it thin! Curing linseed oil is an exothermic reaction and too thick of a pile can spontaneously ignite! 1/2" thick layers are fine. Screen the coated product after several days to de-clump it, you will need to do it a few times.

The magnesium will need several days to two weeks to completely dry.

I would highly advise coating your magnesium, a little prevention has saved alot of trouble!!

I have treated magnesium with potassium dichromate with the method shimizu points out in his book. It has always prevented reactions with AP.
The more I learn, the more I know I don't know.

#8 QED4803

QED4803

    Playing with fire

  • Full Member
  • PipPip
  • 20 posts
  • Gender:Male
  • Location:SE US
  • Interests:Nearly everything with emphasis on reading, learning, outdoors.

Posted 17 January 2010 - 08:33 PM

Is there anything more definite in the literature regarding the use of linseed oil in coating Mg? I would prefer to use linseed oil over potassium dichromate simply to avoid the clean-up and disposal issues, but none of the literature at my disposal describes its use in any detail. There are several specific questions I would like to put to rest before committing a batch of Mg to this procedure, viz:

~How much oil? 2-5% is a pretty wide range.

~Is "boiled" linseed oil truly my best choice? It appears that "boiled", in modern parlance, actually means adulterated with various substances to promote faster polymerization. According to at least one source these adulterants may include chromium and other metal compounds. Might any of these additives cause me headaches (literally or figuratively) somewhere down the road?

~Thinning of linseed oil is traditionally done with mineral spirits--is this a good plan for my purposes?

~How concerned should I be about spontaneous combustion, and what precautions are appropriate in this regard? It is well known that rags soaked in linseed oil have caused numerous fires owing to the exothermic nature of the polymerizing process.

Thanks to all the contributors, from whom I've gleaned numerous bits of knowledge over the past few months,
Smitty

"Good judgement is the result of experience; experience is the result of bad judgement." source obscure

#9 dagabu

dagabu

    Grandmaster

  • Donator
  • PipPipPipPipPipPipPipPipPipPip
  • 8,784 posts
  • Gender:Male
  • Location:Up Nort

Posted 17 January 2010 - 10:48 PM

I have been using Parlon to coat my Mg since Swede showed his preliminary results with it. I keep my Mg based comps outside in a steel container so if they do decomp, I will be fine but no problems so far.
Dave
 
PGI Member http://www.pgi.org
IPA Member http://www.iowapyro.com
 
"The art of fire is indeed the supreme art; for fire is at once the universal slave, the universal master."

#10 NightHawkInLight

NightHawkInLight

    Firebreather

  • Donator - HE
  • PipPipPipPipPip
  • 1,676 posts
  • Gender:Male
  • Location:MI

Posted 17 January 2010 - 11:47 PM

I have been using Parlon to coat my Mg since Swede showed his preliminary results with it. I keep my Mg based comps outside in a steel container so if they do decomp, I will be fine but no problems so far.

I'm interested, how does it preform? Does it do well with AP? Well enough to use water based binders perhaps?

#11 dagabu

dagabu

    Grandmaster

  • Donator
  • PipPipPipPipPipPipPipPipPipPip
  • 8,784 posts
  • Gender:Male
  • Location:Up Nort

Posted 17 January 2010 - 11:55 PM

I'm interested, how does it preform? Does it do well with AP? Well enough to use water based binders perhaps?


I don't think I am prepared to tell anyone else to use Parlon to coat Mg but I do and I use it in water based comps.
Dave
 
PGI Member http://www.pgi.org
IPA Member http://www.iowapyro.com
 
"The art of fire is indeed the supreme art; for fire is at once the universal slave, the universal master."

#12 NightHawkInLight

NightHawkInLight

    Firebreather

  • Donator - HE
  • PipPipPipPipPip
  • 1,676 posts
  • Gender:Male
  • Location:MI

Posted 18 January 2010 - 12:25 AM

I don't think I am prepared to tell anyone else to use Parlon to coat Mg but I do and I use it in water based comps.

Sure. Well I can use my dichromate coated Mg in water based nitrate comps, but still not with water and AP. If you give it a shot be sure to post. Also any positive/negative effects in various compositions that you witness would be great to hear.

#13 Swede

Swede

    Firebreather

  • Donator - HE
  • PipPipPipPipPip
  • 1,797 posts

Posted 18 January 2010 - 10:08 AM

I agree... dagabu, AFAIK you are the first to actually formulate true comps with parlon-coated Mg. My tests were very basic but they did show a very definite protection, superior to dichromate, but ONLY in a simplistic aqueous attack by a mineral acid, HCl. Any results, positive or negative, that you get from the process, would be very valuable.

The other thought I had was that the coating process was very easy with coarse Mg, maybe 30 mesh, but I did not attempt it with a finer Mg. When the Mg is wetted with the non-polar solvent like MEK or acetone with parlon dissolved in it, it initially dried into clumps. When those clumps were broken up, and the drying completed, the Mg flowed nicely - but again, no tests were done with finer Mg.
Charcoal is a preservative, by which the saltpetre and brimstone are made into gunpowder, by preventing the sulphur from suffocating the strong and windy exhalation of the nitre.

#14 Twotails

Twotails

    Pyrotechnician

  • HE Qualified
  • PipPipPipPip
  • 488 posts
  • Gender:Male
  • Location:Over there ----->
  • Interests:Pyrotechnics.

Posted 18 January 2010 - 11:12 AM

What about Saran? think it wold work at coating the Mg?
"Life improves slowly and goes wrong fast, and only catastrophe is clearly visible." Edward Teller

#15 Mumbles

Mumbles

    Grandmaster

  • Admin
  • PipPipPipPipPipPipPipPipPipPip
  • 11,628 posts
  • Gender:Male
  • Location:Above You

Posted 18 January 2010 - 11:47 AM

It could work. Let us know after you try it out.
Just so you guys quit asking, here is the link to the old forum. http://www.xsorbit2....forum/index.cgi

The sky is my canvas, and I have 2,113 pounds of powdered paint in the workshop.

#16 Twotails

Twotails

    Pyrotechnician

  • HE Qualified
  • PipPipPipPip
  • 488 posts
  • Gender:Male
  • Location:Over there ----->
  • Interests:Pyrotechnics.

Posted 18 January 2010 - 02:04 PM

I'll try it tonight after i get back from shooting my shells. How much do you think, 2%-4% dry weight? or is that too much?
"Life improves slowly and goes wrong fast, and only catastrophe is clearly visible." Edward Teller

#17 dagabu

dagabu

    Grandmaster

  • Donator
  • PipPipPipPipPipPipPipPipPipPip
  • 8,784 posts
  • Gender:Male
  • Location:Up Nort

Posted 18 January 2010 - 05:59 PM

I agree... dagabu, AFAIK you are the first to actually formulate true comps with parlon-coated Mg. My tests were very basic but they did show a very definite protection, superior to dichromate, but ONLY in a simplistic aqueous attack by a mineral acid, HCl. Any results, positive or negative, that you get from the process, would be very valuable.

The other thought I had was that the coating process was very easy with coarse Mg, maybe 30 mesh, but I did not attempt it with a finer Mg. When the Mg is wetted with the non-polar solvent like MEK or acetone with parlon dissolved in it, it initially dried into clumps. When those clumps were broken up, and the drying completed, the Mg flowed nicely - but again, no tests were done with finer Mg.


That drove me nuts! I couldn't find a way to resolve this at first and I was convinced that breaking the clumps up was going to strip the Parlon off on side or the other or so I feared. Turns out that there is no noticeable difference between separating (ARRRGGH) it when wet or waiting till dry and breaking them up.

Please, do not use Parlon with AP yet, I have no testing with this yet and I don't want anyone hurt.

Edited by dagabu, 18 January 2010 - 06:00 PM.

Dave
 
PGI Member http://www.pgi.org
IPA Member http://www.iowapyro.com
 
"The art of fire is indeed the supreme art; for fire is at once the universal slave, the universal master."

#18 NightHawkInLight

NightHawkInLight

    Firebreather

  • Donator - HE
  • PipPipPipPipPip
  • 1,676 posts
  • Gender:Male
  • Location:MI

Posted 18 January 2010 - 07:54 PM

Please, do not use Parlon with AP yet, I have no testing with this yet and I don't want anyone hurt.

Well obviously if I tried it for myself I would do my own testing.

#19 Twotails

Twotails

    Pyrotechnician

  • HE Qualified
  • PipPipPipPip
  • 488 posts
  • Gender:Male
  • Location:Over there ----->
  • Interests:Pyrotechnics.

Posted 18 January 2010 - 08:24 PM

Im about to go try coating Mg with Saran, i'll report back with my findings.
"Life improves slowly and goes wrong fast, and only catastrophe is clearly visible." Edward Teller

#20 al93535

al93535

    MODERATOR

  • Moderator
  • PipPipPipPip
  • 435 posts
  • Gender:Male
  • Location:Montana
  • Interests:Pyrotechnics

Posted 18 January 2010 - 08:59 PM

~How much oil? 2-5% is a pretty wide range. 4% will work just fine!

~Is "boiled" linseed oil truly my best choice? Yes it is, its the only choice.

~Thinning of linseed oil is traditionally done with mineral spirits--is this a good plan for my purposes? An excellent choice!

~How concerned should I be about spontaneous combustion, and what precautions are appropriate in this regard? It is well known that rags soaked in linseed oil have caused numerous fires owing to the exothermic nature of the polymerizing process. Leave the trays of drying mg/oil in thin layers, less then 1/2" check it often and sift it often. I wouldn't be to concerned unless you have really large amounts in heaping piles!

Weigh the Mag to be coated. Weigh 4% of that out in Linseed oil. Thin the oil. I used about 7X the weight in volume of solvent. So 100 grams of Magnesium would be coated by 4 grams of linseed oil dissolved in 28 ml of solvent. Mix the oil and solvent well, and pour over the mag. Using gloved hands mix and knead the mg/oil until it is all fully coated. spread on pans to dry. It will take a long time to dry



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 100C 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.
The more I learn, the more I know I don't know.




1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users