aluminum and BP

[kenT]

I would like to add some aluminum powder to my bp rockets for effect. I have the atomized stuff. I see in the compositions boric acid is used. Is that the same as borax??. Is there alternatives?. I am in canada and can't get a lot of the stuff that other countries can.

[Richtee]

I am in canada and can't get a lot of the stuff that other countries can.

 

I'm sure you can get boric acid in a pharmacy type store. It's commonly used as an eye wash. Borax is a soap... and as such I suspect it's a base, and would cause more trouble than not using it. Not that I KNOW... just a hunch. My disclaimer.

 

The dreaded Wiki info:

 

Medicinal

It can be used as an antiseptic for minor burns or cuts and is sometimes used in dressings or salves or is applied in a very dilute solution as an eye wash in a 1.5% solution or 1 tbsp per quart of sterilised water. As an anti-bacterial compound, boric acid can also be used as an acne treatment. Boric acid can be used to treat yeast and fungal infections such as candidiasis (vaginal yeast infections) by inserting a vaginal suppository containing 600 mg of boric acid daily for 14 days (PMID 10865926). It is also used as prevention of athlete's foot, by inserting powder in the socks or stockings, and in solution can be used to treat some kinds of otitis externa (ear infection) in both humans and animals. The preservative in urine sample bottles (red cap) in the UK is boric acid.

Edited November 28, 2008 by Richtee

[FrKoNaLeaSh1010]

You can get boric acid as a roach killer in a home depot or lowes if you have any in your area. The brand I have is Hot Shot MaxAttrax roach killing powder. It costs like 2 or 3 dollars for a one pound bottle thats 99% pure. I'm sure you could find this or similar in your area. Also I thought you only had to add boric acid if you were wetting it (like stars) or storing the composition or rocket for a long time. I never added boric when adding metal to a BP rocket but I usually fired them within a couple of hours. Edited November 28, 2008 by FrKoNaLeaSh1010

[kenT]

Thanks. I will check my local home depot.

 

Does wetting the bp with acetone count when adding aluminum. Will the acetone cause any reactions with it??

[hst45]

It may be labeled as "Orthoboric Acid" as well. I can't see the down-side to using this with acetone, but I defer to the chem majors on this one.

[Miech]

Thanks. I will check my local home depot.

 

Does wetting the bp with acetone count when adding aluminum. Will the acetone cause any reactions with it??

Wetting with acetone does not prevent the reaction between nitrates and aluminium. Boric acid really isn't that hard to find, even potteries and such sell it. If you really can't find it, ascorbic acid (vitamin C) could be used as substitute, but I believe it is somewhat less effective.

[qwezxc12]

Wetting with acetone does not prevent the reaction between nitrates and aluminium. ...snip

 

I'm not a chemist, but isn't the reaction between aluminum and nitrates an ionic one, needing water as a solvent for the reaction to proceed? If your acetone was dried, how could the reaction take place?

 

BTW, this is mostly an academic question...adding Boric Acid to any straight up Al/Nitrate comp (other than glitters using carbonates as a delay agent, obviously) is a pretty safe practice.

[Miech]

It is a ionic reaction, indeed. However, acetone will evaporate out of the mixture and then moisture from the air can enter and cause problems. Besides, acetone isn't an acid so it doesn't prevent reactions between alkalines and aluminum as good as an acid would do. Boric acid gives a long term protection against nitrate/Al reactions, making it way more useful than acetone. Dried acetone will readely absorb moisture from air, so drying it wouldn't help so much.

[Richtee]

Dried acetone will readely absorb moisture from air, so drying it wouldn't help so much.

 

What is "dried acetone"? Don't it just evap completely??

[Miech]

Dried acetone is just acetone without any water in it.

[Richtee]

Dried acetone is just acetone without any water in it.

Ahhh...OK got ya. I was confused there..."Anhydrous".

[qwezxc12]

The only time I bother to "dry" my Acetone is before use as Go-getter solvent or to make NC laquer. I use either Calcium Chloride (Damp-Rid) or Molecular Sieves. Both work well at absorbing moisture out of the acetone.

[Richtee]

The only time I bother to "dry" my Acetone is before use as Go-getter solvent or to make NC laquer. I use either Calcium Chloride (Damp-Rid) or Molecular Sieves. Both work well at absorbing moisture out of the acetone.

 

OK... pleading ignorance. Please explain why I'd want to do this when making NC, and HOW to do this? Thank you!

[tentacles]

For go getters and another AP formulas with Mg or MgAl + AP, it's better to have dry acetone for the NC.. Dry it by tossing in some calcium chloride (dry it in the oven first). Just fling it in the can, or make a little bag and put that in the can. Molecular sieves are preferable, really, but harder to get and more expensive.

[Mumbles]

I get my molecular sieves from Paul Sorrentino. Great guy and great product. They last damn near forever, and are extremely efficient. I was always weary about getting some calcium suspended in my acetone and ruining colors. Probably a non-issue if you're careful. It can also complex with Acetone, but I'm not sure if thats soluble or not. I just keep a handful of sieves in the bottom of my acetone jug to keep it always dry. Well dry enough for our purposes. The amount of water that it will absorb by sitting out, or evaporating is negligible.

 

http://www.pnjresources.com/Molecular_Sieves.htm

 

You want to dry said acetone to prevent the reaction between Ammonium Perchlorate and Magnesium specifically. This is why it is done for go-getters. Ammonium Perchlorate very much doesn't like magnesium, and will react happily with it. Generally the Mg is also treated too as an extra layer of protection.

 

In general I wouldn't be worried about the small quantity of water in acetone causing a reaction between nitrate and aluminum. Your KNO3 probably contains far more water than the acetone. Add boric acid if you want to, but it probably isn't neccecary unless you're storing the motors for extended periods of time in a humid environment. Then you'll face other challenges anyway.

 

I actually have no problem with using boric acid in carbonate containing glitters. It's not strong enough to protonate the bicarbonate to carbonic acid. IE, the boric acid doesn't destroy the carbonate delay agent. I've successfully used it multiple times in combination with carbonate and bicarbonate delayed glitters with no issues. It prevents reactions that were happening otherwise as well.