Making ash

[jafa5]

I'm collecting a number of materials to render down to ash after reading some of the feedback on ash glaze posts, most memorable is a comment from Oldlady about a potter collecting ash from specific trees and each one being different.  Anyway, l've started collecting a few items from the garden including maple seed pods and the seed tops from Vietnamese mint.

The quandary is how to burn them green and collect the ash.  Initially I thought i'd just light them in a cleaned fire place but i'd need to use paper or some other ignition source to get it started which would contaminate the ash.  So now i'm thinking i'll use the gas burner from one of the kilns or brewery and fire them in a cast iron pot.

How have other people done this? 

Also is it any different to make ash from green vegetation compared to dried vegetation?

Cheers,

Liam

[Fred Sweet]

jafa5-

i used to put my materials in a bisque bowl and fired it in a gas kiln. Just realize that it takes a lot of material to get a substantial amount of ash.

I once used 2- 33 gallon trash bags of dried rose petals to end up with 1/8 of a pound of ashes. Took a good amount of time to do it, only to find that the ash was high in colloidal silica. Interesting experiment and fun, as a teaching experience, for a couple of my students.

Dry materials will convert easier than fresh, green ones. You will need a lot of air in your firing to get a good amount of ash without leaving lots of carbon in the ash. I’ve also done the burning as a “campfire” in my fireplace.

I don’t think that the amount of starter material (paper) will make a significant difference in your ash if you are burning a lot of material.

Hope this gives you a place to start your investigations.

Regards,

Fred

[jafa5]

Thanks Fred!  I hadn't considered putting them in the gas kiln but not sure it has enough volume.  

I'll do it in the fireplace as you suggest and dry it first. 

A bit of fun if nothing else

[Fred Sweet]

jafa-

Don’t have to burn them all at once. A little at a time adds up!

Fred

 

Forgot to say: I did a lot of my burning in a raku kiln. Just have to take it up to about 500*F or so and hold it there for a while.

[curt]

100 kilos of wood delivers about 1 kilo of ash.  Your mileage may vary (but not by much....).  

That said, I would encourage you to spend a bit of time on this, because not only do different species of trees have different ash compositions, different parts of the same tree have ashes which differ considerably in chemical composition.

I have produced small quantities of “specialty ash” in my fireplace firebox by waiting until the main fire burns down to a good hot bed of coals, then putting my special materials into an old metal baking pan and simply setting it on top of the coals and closing the door.  This works most of the time, and with pretty much minimal contamination of the desired material.  

‘The baking pan doesn’t seem to like the process too much, but somebody’s always got to pay...

 

[JohnnyK]

I'm not a Chemistry major, but I think the primary difference between the green material and the dry material is H20. If that's the case, I would gather up a lot of whatever it is you want to burn, let it dry out on its own or force dry it in an oven or a kiln, place it in an appropriate rendering vessel, and light it up with a propane torch. As Fred says: "Don’t have to burn them all at once. A little at a time adds up!"

Just save your different ashes in different containers until you have enough to do some tests which will help determine which ashes do want you want so you don't spend a lot of time and effort accumulating ash that won't work for your purpose.

JohnnyK

[jafa5]

I made my first small batches this week and yes only small amounts but will add up.  The pan didn't like it Curt

Hopefully mine isn'the high in colloidal Silica Fred, but to be fair i'm not sure if i'do know what would happen with that. Glass former that very runny?

Lots of small batches to find a good one is a great way to start.  I used a volcanic as this week that we found on my building site which turned out really nice, i'llc photograph and post.

Thanks for all the input guys, really appreciated.

Liam

 

 

[hitchmss]

More "glass" or flint/silica/quartz doesnt always mean more runny. Its a relationship between flux and flint that produces the runs. Silica melts at 3000 deg +; we dont fire that hot. Feldspars/fluxes aid in lowering the melting point of silica. More silica in a runny glaze actually stiffens it; contradictory to thought, but more glass means less flux to make it melt.

There was a wonderful article in either CM or PMI which showed the difference in ash from different tree species, harvested at different times of year, and from different portions of the tree. Had great images and documentation. Dont remember which issue, or who the author, so maybe someone else does?

 I use ash which is all mixed hardwoods; burnt in my woodstove in the winter and turned into glaze in the summer. I screen, and wash my ash (put into bucket of water, blunge, let settle, siphon off top layer, and repeat/continue to do this until water no longer feels soapy or smells). Takes a lot of ash for me to produce a little glaze, and it takes a lot of wood/material to produce a little ash. For small amounts Id throw it into a bisque bowl and fire it with your bisque loads; make sure kiln area has plenty of ventilation (smoke.!!)

[tomhumf]

I've collected some ash from the local wood fired pizza oven restaurant. Not used it yet, but its very handy to turn up with a tub and collect from their ash bin!