Wood Ash

[dagr8tim]

So today I cleaned out my fireplace, and I'm left with a 5 gallon bucket of wood ash. I'm wondering if it's usable for forging, and if I should maybe sift it before using it or what to do with it. I didn't burn all the wood that produced the ash, so there could be ash from some of those fireplace logs (wax and sawdust), or even parts of furniture.

Before I go any further, I'm wondering if it's worth messing with or if I should dump it on the ash pile behind the garage.

[BIGGUNDOCTOR]

I never sifted them, just dumped them into a cutdown 55 gallon drum. If there was any waxes, etc they have burned off, don't worry about what was burned. The main thing is that they are the gray ashes, no charcoal. This will make a great annealing medium. Before use, take a stick and stir them up all nice and fluffy, as they tend to settle down. Cover well to keep dry.

[Sam Falzone]

I never sifted them, just dumped them into a cutdown 55 gallon drum. If there was any waxes, etc they have burned off, don't worry about what was burned. The main thing is that they are the gray ashes, no charcoal. This will make a great annealing medium. Before use, take a stick and stir them up all nice and fluffy, as they tend to settle down. Cover well to keep dry.

Yup Biggun, you beat me to it.

But I've always been told to sift out any big "bits" and charcoal to keep it fine as possible. Why spend money for vermiculite when you can get wood ash for free for all your annealing needs.

Not so much of a health concern with wood ash as with other annealing mediums, like vermiculite. :huh:

[CurlyGeorge]

I agree with sifting out the charcoal, Sam. Way back, the very first time I used ash for annealing, I had the ash in a large box. I set it just outside of the garage,(thank God), and the charcoal started to burn. Burned a hole in the box before I realized what was going on. Now I sift!!! :blink:

[Frosty]

Ditto what Guns said.

Frosty the Lucky.

[son_of_bluegrass]

There are a number of uses for wood ash. As has been mentioned, it is a good annealing medium. It can be used to line a forge or mixed with what you use to line a forge. I read of ash being used as a flux, some say it has to be rice straw ash specifically, others say any straw ash (straw ash will have some silica in it), others say any ash will work. I've never used ash of any kind for flux.
Since you mentioned furniture, I'd sift it. That way any leftover metal bits from the furniture will be removed and the charcoal you can save back for forge fuel.

ron

[evfreek]

I have heard that you can put lump charcoal ash in the compost heap, but not ash from charcoal briquettes. Supposedly, there is too much coal in the latter. I don't know about this. It seems that the coal in charcoal briquettes is more like coke, and has most of the sulfur cooked out of it. This is not true with cheap Chinese cooking bricks. They have so much sulfur in them, it really makes the food taste foul.

Wood ashes are alkali, and will keep down the odors in the compost heap. I once did a study on this, and any quick lime generated from roasting the calcium carbonate naturally present in the wood can transform the potash into lye, which is a little harsh for the garden. Oddly enough, I have found wood ash water from forge ashes has much lower potency than regular ash water. It may be due to the lower residence time.

[Glenn]

Run it through a screen wire. This will remove all the junk and unburned charcoal. Just be sure and keep it dry.

[lordcaradoc]

Well, since everyone else gave the Smithin' uses, there are loads of other good things to use fireplace ashes for:

Ten uses for Wood Ashes

Of course, you can also use it in the old Outhouse instead of lime.

Regards,
Tim

[dagr8tim]

Well, since everyone else gave the Smithin' uses, there are loads of other good things to use fireplace ashes for:

Ten uses for Wood Ashes

Of course, you can also use it in the old Outhouse instead of lime.

Regards,
Tim

Good list. We also used to to shine up the metal runners on our sleds when I was a kid.

[pkrankow]

When fluxing with wood ash, another thread mentioned to wrap the billet in clay soaked paper to create a "can weld" effect.

Phil

[lordcaradoc]

When fluxing with wood ash, another thread mentioned to wrap the billet in clay soaked paper to create a "can weld" effect.

Phil

Clay Soaked Paper? Can you link that thread? I am confused, but always interested in learning.

Regards,
Tim

[pkrankow]

Clay Soaked Paper? Can you link that thread? I am confused, but always interested in learning.

Regards,
Tim

I misremembered slightly.

Phil

[Maillemaker]

Anyone have their ashes stick to the workpiece after annealing?  Like superglue stuck?

[notownkid]

One question,  I hope your fireplace wood ash is Not in a plastic 5 gal bucket.  That practice starts a huge number of house fires each year.  Clean the fireplace, fill the bucket and then put the bucket on a wooden floor, maybe the wood pile and bingo there goes your house.  I've personally seen at least 15 in the yrs. of fighting fires in VT and CT.

[Glenn]

Sift all the junk out of the ash by running it through a window screen or other fine material. Reburn any of the combustible materials. 

 

When the snow flies, use the ash to define the walk or the drive way. The sun comes out and the dark gray absorbs the heat and melts the snow or ice. It then benefits the ground or yard come spring. 

[petere76]

Glen,

Same thing in our dooryard when it freezes over, we spread the ashes from the wood stove so you don't crash walking to the outbuildings. Works great. We keep a few 5 gallon pails in the shop to anneal tooling overnight. Even at below zero temps the pieces still warm to the touch in the morning, amazing insulation properties.

Peter

[arftist]

I like to use a galvanzied "ash can" or 20 gallon metal trash can with a lid. I try to keep it at least half full. 

 

Almost any cast iron weldments get buried in there for slow cooling after welding. Also good for annealing though not good enough for some alloys. Some alloys need to be annealed in a cooling forge or woodstove/fire or of course a heat treating oven. 

[gote]

Maybe this should be in the alchemy section but:

 

If there were no oxide layers on the steel surfaces, welding would be very easy and could even be performed at room temperature. Unfortunately there is only contact in points since the surfaces are not absolutely flat. Normally we need to raise the temperature to a level where hammer blows will give total contact.

 

Then there is always an oxide layer even if it initially is invisible to the eye. We have to get rid of that. Iron oxide has a lower melting point than steel so very high temperatures will melt the oxide so it can be squeezed out from the joint. Unfortunately that temperature is close to the temperature when the steel is overheated. The carbon in the outer layer may also be oxidized away which is a nuisance in blade smithing.  

 

By managing our fire we can make sure there is no free oxygen in the area where we heat our steel. (This is what we do when welding with Acetylene). Instead we may have carbon monoxide which actually can give off small amounts of carbon to the steel surface. Making sure the oxygen is consumed, is probably a very (the?) important factor.

 

Borax is a helpful material since boron trioxide will combine with many different metal oxides to form a kind of glass that is liquid at relatively low temperatures. The Borax-Iron-oxide melts at lower temperatures than Iron oxide does and thus it facilitates the welding.  Obviously we must get some of the borax into the joint for this to happen. Fortunately the borax itself melts at a relatively low temperature (743°C) so it can be sucked into the joint by capillary action. The borax will also form a cover that slows down ingress of oxygen.  Borax thus helps us in two ways: #1: fluidizes the oxide at a lower temperature #2: stops oxidizing by forming a protective layer.

 

Silica sand is also useful since silicon-iron compounds have some 100°C lower melting point than iron oxide. Thus a very fine powder of silica is beneficial to get the oxides out of the joint even if not quite as efficient as borax. Silica in itself has a very high melting point so it will not suck into the joint. Because of the high melting point it will not alone stop the oxygen but perhaps form a kind of iron silica glass. If we mix fine silica with potash and/or soda and/or limestone we will create a glass which has a melting point not far from that of borax. How quickly that happens depends upon the grain size of the mix. Sand is rarely pure silica. (Even when sold as “silica sand”) There are usually other elements as well. These may explain why sand can be used as a flux – or does it combine quickly with the iron oxide?

 

Rice straw ashes contain some 75% silica and 15% potash both in very fine state and I think that this is important. I would thus assume that it quickly forms a glass (melting point 760°) containing surplus silica that can be sucked in and probably also fluidize the iron oxide. It seems to me that the Japanese method of coating a cherry red billet with ashes will immediately form a thin cover of glass.

 

 The content of silica in plants varies a lot from species to species so one cannot assume that any straw ashes will work. Ashes of horsetail (Equisetum) would probably work well but who burns sufficient amounts of horsetail? Wheat straw ash varies in silica content from ca 35% to 60% Some types of wood ash contain up to 35% but most types contain small amounts. However, wood ash may contain calcium oxide (quicklime) that will transform into calcium carbonate (limestone). Wood ash typically contains potash and some soda and so heated together with fine silica it may also form a glass but it will be difficult to find a source of sufficiently fine silica to get even near the speed of rice straw ashes.

 

The Japanese also use clay slurry. Unfortunately we do not know what it contains. Clay is predominantly Silica-Aluminium-oxide but it can contain other elements like potassium and sodium and there is a large number of clays that have different high-temperature properties.. Clay is very fine grained and the grains are platy; thus the slippery consistency. As we all know clay will fuse into ceramics when heated. Japanese raku ceramics is burnt at only ca 800°C. A suitable clay (maybe with added “agent X”) may form a glassy layer that prevents the billet from oxidizing.

 

If we first dip the billet in the rice straw ash, and when that has formed the glass, dip it in something else, I assume it will act as glue for the next layer.

 

My conclusion is that the smith’s best use for wood ashes is annealing. Should he have rice straw ashes they are useful in welding. If he can use other types of ash depends upon what the species is and where it grew. Only experiment will tell.

 

Cheers

Göte

[njanvilman]

Since I burn some old wood that contains nails and other fasteners, the ash residue is not clean.  I dump all of it down groundhog holes around my property.  Buries the hardware and gets rid of the ash all at once.

[Stefflus]

 However, wood ash may contain calcium oxide (quicklime) that will transform into calcium carbonate (limestone)

Yes, but hardly in an atmosphere exceeding 900^o C. In exceeding amount it might make slag doughy though because of its high melting point

[SmoothBore]

 

 

" When the snow flies, use the ash to define the walk or the drive way. The sun comes out and the dark gray absorbs the heat and melts the snow or ice. It then benefits the ground or yard come spring. "

 

 

That's all true, ... and in years past, was common practice.

 

However, today, ... tracking that into the house would earn me a stern lecture.  :rolleyes:

 

 

 

.

[Frosty]

That's all true, ... and in years past, was common practice.

 

However, today, ... tracking that into the house would earn me a stern lecture.  :rolleyes:

 

 

 

.

 

You could suggest she might prefer a little ash on the mud room floor to having to pack your carcass in if you slip on the ice and break something.

 

Yeah, I dust the driveways with ash from the stove but I have to be really careful not to toss ANY where it's not clear gravel or dirt. Snow may cover dry grass, leaves, sod, etc. but it's not wet so it WILL burn. Ash from a wood stove can contain live embers for up to two days. I have two covered ash buckets I empty the stove's ash tray into. When one starts getting full I spread the weeks cold ash from the OTHER bucket. I can be pretty indiscriminate that way. I've never found a live coal after a couple few weeks in a covered bucket.

 

Spreading ash can work a treat but you gotta be careful.

 

Frosty The Lucky.

[gote]

Yes, but hardly in an atmosphere exceeding 900^o C. In exceeding amount it might make slag doughy though because of its high melting point

Yeas of course but I mean that before it is used as a flux, it is likely to be carbonized to calcium carbonate (CaCO3). In itself it has a high melting point but it is likely to react with the other ingredients to form a glassy substance with lower melting point - especially it will lower the melting popint of pure silica. This is why it is used to form slag in blast furnaces. One obvious disadvantage with wood ash is that it varies a lot and if CaCO3 makes up most of the ash, you are probably right.

Göte

[Charles R. Stevens]

Of corse "white" ash from a hardwood fire makes a passable leavening agent when your out of baking powder, lol.
Hardwood ashes also make a respectable scouring powder, as well as discouraging mites in your chicken coup.