Muriatic acid works the same and faster than vinegar. It’s available everywhere.
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Goran, you plan to use the mesh on the moped?
If so, a word of caution. 2 actualy.
First, charcoal gasifiers dont produce soot, but actual grey ash, quite different thain wood gasifiers. You realy dont want that in the engine, feels like sand paper. It also cakes differently.
Second, l have found just the other day, on my BCS walk behind, that sack filtrrs are no good for single cilinder engines. The pulsation of the intake shakes the sack so that no cake can form, and it just starts to let dust trugh. Its the first time l ever had a problem with a sack filter, l am yet to find a good substitute…
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KristijanL,
Consider trying alternating layers of thin open cell foam and layers of tighter weave sheep’s wool fabric formed into an all-must-flow-thru stacked block. Mildly compressed.
It should survive and absorb the pulsations and be washable; reusable.
Regards
Steve unruh
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Dear Göran,
just as a silent follower/reader of your topic so far, I wonder if you dont want to try many small tubes of the filter material in a bundle instead of a big star? Would be easier to build, and you could replace single tubes if there are some damaged.
Kristijan, do you still use a towel? In second World War, some recommended woolen felt as filter material for charcoal gasifiers. Less sensitive to moisture and heat than cotton, and with suitable thickness no paths for particles (no sun can shine through the fabric).
Well as Steve Unruh wrote, just without the foam.
Regrads,
Til
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on google immagines i have looket to the chicago clipper… how much turns it makes?
interesting tools , maybee it is a pitty make in pieces for other use, because can be useful for beard and hair cutting… 
maybe you can make an additional job as ambulant hair and beard styler, driving around with the chargas moped…my son makes teeth extraction, but there are not much customers confidence, the only customer i am…
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Hi Kristijan, no the mesh im going to try out on the Chevrolet hot-filter, it’s going to be near 10m2 surface, instead of the welding blankets i used before.
On the moped i use a sock made of cotton curtain, im probably going to replace it with sheeps wool if it fails.
Many thanks for the words of caution, im going to check this up, being aware of the pulsating gas suction.
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Hi Tilman, yes i’ve thought about them tube filters, i also have Mikkonen’s drawings and building instructions of them, but it just feels to cumbersome and expensive to build for me, as i used cheap welding blankets before it’s almost impossible to sew those filter hoses, Mikkonen uses Nomex material (expensive) but can be sewed on a household sewing machine.
If i could find some ready usable filter material in hose-shape, i would try it.
As for the ss metal-mesh, i believe it would be easy to roll hoses/tubes and use but it would need more material (overlap) and im a little penny-wise 
I also believe tubes of this metal-mesh would be a little to stiff, i want the filter to “breath” some, to release soot-cakes.
Much of my goals with this filter is to get it self-cleaning, wich worked good with the welding blanket build, it just dont become a “eternal” filter. 
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Hi Giorgio, the good thing with my chicago clipper is it was broken when i found it, the piece that holds the flexible shaft is broken (cast iron) and missing, also the flexible shaft is missing, so i can re-purpose it without feeling bad. (I’ve already used the feet/stand to mount a working-lamp on)
As for the gearing i have to check that up, but it really spins when up to speed.
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Hi Tom, muriatic acid i haven’t seen in a while, it seem’s farmers are’nt using it for silage anymore? Not around here anyways.
I wonder if citric acid would work? That stuff i have a lot of.
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It usually used for cleaning off masonry here Goran. All the hardware stores and places like Home Depot carry it. I think any acid will clean metal. I’ve seen coca cola poured down spark plug holes free up cylinders. Phosphoric Acid.
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I think citric acid would work very fine. When I wet tumble my brass shells I add dishwasher conditioner with citric acid and it makes brass super clean. I bet it would eat zinc right off of anything.
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Hi Goran, a good self-cleaning filter… I know two variants of filter cleaning, the first is mechanical shaking and the second, blowing with compressed air, but blowing is also carried out in several ways, one of them is the lowering of air blasts in the opposite direction of the flow. a similar effect is created by the blowback of the fire in the suction pipe. Filter cleaning is always carried out when there is no flow through the filter, for our purposes this would be when we take the gas off the engine, say on a downhill slope. Mechanical shaking would be feasible, but blowing out would be very difficult.
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Hi Tone, yes there are many ways to accomplish a self-cleaning filter, the hot-filter i’ve used on my Chevrolet is built by very large surface area, this has worked good until now (leaking) i never had to brush or blow it, due to large surface area (13m2, 7should be enough to this engine according to Maxgasmans formula, wich i dont can find)
Due to construction, no places where the soot build-up can hang up, and low pressure difference over the filter media, this has worked really well, on vacuum gauge after filter i can see how restriction increases, then let go of accelerator just 2 seconds, when i hit the accelerator again i can clearly see how the restriction over filter has got back to normal, my opinion of this is: due to decreased pressure the soot build-up falls of the vertical fillter walls, wich is about the same as back-blowing the filter as you say.
Anyway this filter has dropped it’s soot-cake even during long drives without releasing throttle, due to the weight of the soot-cake, probably.
Anyway it’s interesting to come up with ideas of filters that “rinses” themselves, i have somewhere pic’s of a war-time charcoalgas filter with brushes hanging in springs, constantly brushing the bag filter during driving, bumps and uneven roads, don’t know how much it will wear the bag though?
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That just conjured a imagine in mind of either a bag house filter/tube or any other hanging filter for that matter, with inside a hanging chain with a few ball bearings placed along it. A wind chime of sorts, allowed to bounce around inside the filter with sway of the truck and bumps in the road to have a constant light nocking around inside the filter to release the soot cake
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Marcus, that is ingenuity (spelling?) at it’s finest, beautiful in it’s simplicity, i like it
I imagine something like a ball or the “sausages” you hang on sides of boats, to keep them from “gnawing” when they are “parked” (sorry for the translation) , hanging from springs inside the filter bag, just to have something that not scrape or wear the bag.
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Nomex fabric can sometimes be found in used clothing.
I got these 2 Firefighters Nomex station-ware pants at a thrift store on old-man discount day for $4.00 each.
LION duty ware brand.
Lots of filtering material in my big-assed size.
S.U.
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That is a really good deal, SteveU, i only wish i could find some here in Sweden that way, but firefighters stand under municipal/government control, wich means: supplier of fire resistant clothes make them promise to NOT sell or give away anything in Sweden, give to other countries are okay, this is only to avoid their own used stuff to compete what they sell new (like it’s a big market for firefighter uniforms 
) they often have some bad excuses, like the clothes are’nt safe when they are used just one time.
This is only, what i believe sellers/buyers scratching each others back’s, handle money under the table.
(Alot of this is confirmed, when i asked local firefighters) anyway i got tip of a upholstery shop that repaired clothes for the firefighters, that way i got a lot of fireproof sewing thread.
Enough rambling about that, another way i checked is those racing overalls, mandatory in every motor-sport here, but even the second-hand value of these nomex-overalls is to high.
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I thought i throw out a question, i believe there are better info on the other side of the pond,
On my Chevrolet i have Gm hei ignition (wich i like, and it works well with woodgas) problem is i want a tachometer, and everyone i find around here says: not for electronic ignition, or even not for hei, ofcourse i’ve tested anyway, the signal wire (- on coil) i connected to the “tach”-terminal on the dist, the first meter lasted 2 month’s, the second, little better quality, lasted 6 month’s the third, cheap one, lasted 3 years, i know there are tachometers that works with hei, but here they are to expensive, and “converter boxes” (msd) more expensive than a special tachometer.
Any ideas?
Im going to keep looking on the net for a cheap one that says hei compatible, but mostly they just show a diagram with the signal connected to negative on a coil.
As an example i asked a car parts reseller, they recomended me to buy a aftermarket hei ignition with mechanical tach drive (flex shaft like an old speedometer) of course a solution, but not what i want… 
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According to last post, i believe my english has got better, i’ve found several diy tach signal filters/schematics, i believe i have the components needed already.
Just some things i cant understand: why cant this stuff be found in europe? And everyone keeps telling you cant connect a standard tach to a hei dist?
And: how can the signal from a hei dist be more noisy than from a coil negative? Everyone that has touched the negative terminal on an ignition coil with engine running, or pull this wire with ignition on and points closed should know what i mean? 
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I’ve done that Goran. Try it with a magneto. It’s not fun when all the fillings in your teeth become a tesla coil. I’ve even done it on a motorcycle at 70 MPH.
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