12 replies to this topic

[pyrotechnist]

How do you go about coating coarse iron powder with linseed oil? I aint sure whether you are supposed to add the linseed oil to say a non stick frying pan and heat it up adding the iron once boiling and then evaporate the linseed oil off or just add it in a cold state and let it dry. Which ever method is correct is there a rule of thumb for how much linseed oil should be used?

[Bonny]

How do you go about coating coarse iron powder with linseed oil? I aint sure whether you are supposed to add the linseed oil to say a non stick frying pan and heat it up adding the iron once boiling and then evaporate the linseed oil off or just add it in a cold state and let it dry. Which ever method is correct is there a rule of thumb for how much linseed oil should be used?

I think you can do it cold, but I've never tried. I did the coating by heating the iron in a pan then stirring in the linseed oil 2-4% by weight IIRC. Keep stirring until all the iron is caoetd, then remove from heat and continue stirring for awhile to prevent clumping. Let it sit out and dry for a week or something and screen to desired sizes.

[cooperman435]

I added 5% by weight stirred it all together than heated in a wok slowly until it dried off totally.

[RFD]

Use boiled linseed and a small amount of terebine driers mixed in,linseed oil wont evaporate it has to air dry,mixing cold is ok and let it drain and then warm on plate or in a pan.
If you do boil linseed please be careful as i had a very unpleasant moment boiling up linseed for gunstock finishes,it seems to get to a point of heating where it generates its own heat and ignites,over boil linseed and a new kitchen will be needed,ive done the linseed thing with iron and magnesium and its a messing time consuming PITA,but a necessary evil sometimes.

[pyrotechnist]

Thank you so basically the cooking just super evaporates the oil allowing you to use the iron sooner? By the way how long can an iron based mixture be stored for without the iron being coated before it turns to rust?

[dr thrust]

the reaction of the kno3/ fe will start pretty much straight away, if your making shooting the same day you'll be fine, as an alternative to linseed oil, you can melt in a bit of paraffin wax

Edited by chris m, 19 October 2009 - 06:27 PM.

[starseeker]

How do you go about coating coarse iron powder with linseed oil? I aint sure whether you are supposed to add the linseed oil to say a non stick frying pan and heat it up adding the iron once boiling and then evaporate the linseed oil off or just add it in a cold state and let it dry. Which ever method is correct is there a rule of thumb for how much linseed oil should be used?

I had a interesting conversation with the rev lancaster when we visited the factory earlier this year regarding this and he told me they just add the boiled linseed in the proportions allready mentioned,leave for 24 hours and then it is perfectly fine to use,no heating required.

[digger]

Thank you so basically the cooking just super evaporates the oil allowing you to use the iron sooner? By the way how long can an iron based mixture be stored for without the iron being coated before it turns to rust?

Nope linseed oil is what is known as drying oil. Basically it has an auto catalytic polmerisation reaction where the oil molecules start to bond together in the presence of oxygen. The action of heat just speeds this reaction up (and makes it smell more). So yes you will be able to use it sooner, but maybe not worth the effort as it will work either way, it is your choice.

In the industry I work in one of our waste products is fullers earth contaminated with oils that have this property. The auto catalytic reaction can be so strong that this waste often just sets on fire with the heat produced by the reaction. No need to worry though as this is only in 30 tonne skips with a bit more oil than you will be using.

Edited by digger, 19 October 2009 - 09:14 PM.

[pyrotechnist]

Thank you all for your help I guess I will just leave it to dry for a week then and fingers crossed it will work .

[Bonny]

Thank you all for your help I guess I will just leave it to dry for a week then and fingers crossed it will work .

As long as it's all coated I'm sure it will work just fine. From what I've read, a week might be minimal if not heating, but if others do it then I guess it works. I'd recommend stirring now and then too, to help reduce clumping.

[BrightStar]

To add to the above, hardware store boiled linseed oil usually contains the terebine dryers already. It's cheaper to produce commercially this way but seems to work fine for our purposes.

Stir-frying the iron filings over a gentle heat is still helpful to reduce the viscosity and evenly coat the metal. Alternatively you can thin the oil with a solvent and do it cold. Either way, I've needed to allow 2-3 weeks drying time.

A safety note... Boiled linseed oil has burnt down several unsuspecting artists' workshops as their oil-soaked rags self-combust in the bottom of their bins. Take care!

Edited by BrightStar, 21 October 2009 - 09:02 PM.

[pyrotechnist]

Does the linseed oil also protect the iron from oxidizing and turning to rust if exposed to air or a humid environment?

[Bonny]

Does the linseed oil also protect the iron from oxidizing and turning to rust if exposed to air or a humid environment?

That is the reason for coating it...to prevent rusting from air/ humidity in storage and from nitrates, which also oxidize it.