View Full Version : Any metallurgists in the house?
Skidsteer
02-15-2007, 19:56
I recently made a potstand from stainless steel wire mesh dirtbagged from a bird feeder. I'm pleased with it but...
Does all stainless steel form carbon on the surface when heated or is this just an inferior grade? It makes quite a mess and it's a pain to clean.
Anyone know how to prevent this?
Thanks.
Does all stainless steel form carbon on the surface when heated or is this just an inferior grade? It makes quite a mess and it's a pain to clean.
Well, they've been making frypans and skillets out of stainless for a long time... Are you sure the carbon wasn't deposited by the fire/flame itself? Was it a clean flame?
Jim Adams
02-15-2007, 20:06
The carbon is probably coming from your fuel and a poor flame.
geek
Skidsteer
02-15-2007, 20:07
Well, they've been making frypans and skillets out of stainless for a long time... Are you sure the carbon wasn't deposited by the fire/flame itself? Was it a clean flame?
Yes. Same SLX denatured I usually use. I had a thought originally that it was caused by some kind of residue or coating on the mesh-but washing it in dish detergent didn't help. :confused:
Skidsteer
02-15-2007, 20:10
The carbon is probably coming from your fuel and a poor flame.
geek
It's not(trust me, I'd know). The same stove with the same fuel using a mesh stand from galvanized metal doesn't produce the sooting. Same thing with an aluminum stand-no carbon. Just this 'stainless steel'.
I'm not a metallurgist, but I have worked with iron and steel off and on quite a few years. Been a part-time blacksmith 20+ years as a hobby and read quite a bit on metallurgy. There are many kinds (alloys) of stainless steel. Some will rust, most will not. Some will stain or tarnish, some will not. Some are magnetically attractive, some are not. Some will harden and temper, some will not. A steel must contain at least 10.5% chromium and 50% iron to be classed as a stainless steel. The other 39.5% can be any metal that will alloy with the iron and chromium depending on the properties desired in the finished product.
Yes. Same SLX denatured I usually use. I had a thought originally that it was caused by some kind of residue or coating on the mesh-but washing it in dish detergent didn't help. :confused:
Well, then, I can't help ya. I hiked and cooked with a stainless pot for years. The only carbon I saw was when I set it on my Zip stove. ;)
Should be alright after the first burn.;)
Try heating it with a plumbers torch to burn off the impuritys in the SS. If it smokes when heated its working.
Skidsteer
02-16-2007, 09:12
Try heating it with a plumbers torch to burn off the impuritys in the SS. If it smokes when heated its working.
I'll give it a try. Thanks.
gdwelker
02-16-2007, 10:01
How do you know that what you have is stainless steel? Test with a magnet - if it attracts, it's either not stainless, or very low grade.
My guess is that you have a piece of zinc coated or bright galvanized wire mesh. Either of these, especially the zinc, could produce amounts of black carbon like residue. You don't want to be breathing zinc or galvanized fumes.
Skids, what size mesh is it? The smaller the mesh, more likely to show soot.
What distance from flame?
Skidsteer
02-16-2007, 10:07
How do you know that what you have is stainless steel? Test with a magnet - if it attracts, it's either not stainless, or very low grade.
My guess is that you have a piece of zinc coated or bright galvanized wire mesh. Either of these, especially the zinc, could produce amounts of black carbon like residue. You don't want to be breathing zinc or galvanized fumes.
It doesn't attract to a magnet.
4eyedbuzzard
02-16-2007, 12:04
The carbon is probably coming from your fuel and a poor flame.
geek
Ding! Ethanol can produce soot. Methanol does not.
SLX Denatured is a mix of Methanol AND Ethanol (no MSDS available but estimates are between 17 and 50 % ethanol) and 3% Methyl Isobutyl Ketone. Other denatured products, such as Park's, sold as thinners are similar.
Buy HEET(yellow, not red) or other products known to be or labelled as pure methanol.
Bottom line -- if there's any yellow in the flame, there's carbon being produced. If the flame is pure blue, it's clean.
Skidsteer
02-16-2007, 17:22
Ding! Ethanol can produce soot. Methanol does not.
SLX Denatured is a mix of Methanol AND Ethanol (no MSDS available but estimates are between 17 and 50 % ethanol) and 3% Methyl Isobutyl Ketone. Other denatured products, such as Park's, sold as thinners are similar.
Buy HEET(yellow, not red) or other products known to be or labelled as pure methanol.
Bottom line -- if there's any yellow in the flame, there's carbon being produced. If the flame is pure blue, it's clean.
Thanks for the info guys, but it's not the fuel. Yellow Heet does the same thing. As I said earlier, the carbon is only a problem with this stand and no other.
I'll try the torch solution when I get a chance. I have a feeling the S.S. is a poor grade and there lies the problem.
Any other fixes?
Two Speed
02-16-2007, 17:29
Skids, I've got a pretty good sized chunk of stainless mesh that's worked out pretty well for me. Let me know if you want a piece of it and we'll work something out. Got it from McNichols (http://www.mcnichols.com/about/contact/branches/atlanta.htm); rated for 1600 degrees farhenheit if I remember correctly. Used to be just down the road.
My husband is a metalllurgist. I'll ask him when he gets home. My guess is it may be the grade of stainless. Stay tuned.
How do you know that what you have is stainless steel? Test with a magnet - if it attracts, it's either not stainless, or very low grade.
My guess is that you have a piece of zinc coated or bright galvanized wire mesh. Either of these, especially the zinc, could produce amounts of black carbon like residue. You don't want to be breathing zinc or galvanized fumes.
If this is true the torch will burn off the galvinize and zinc but then it'll probably rust. Take the offer of the stainless in another post.
Skidsteer
02-16-2007, 18:24
Skids, what size mesh is it? The smaller the mesh, more likely to show soot.
What distance from flame?
1/4" on center. Stand is 3/4" above the stove.
Skidsteer
02-16-2007, 18:27
Try heating it with a plumbers torch to burn off the impuritys in the SS. If it smokes when heated its working.
I hit it with a Mapp gas torch for 3-4 minutes and the carbon problems are about half what they were.
Think I should torch it some more?
Two Speed, Is it 1/2" wire mesh? Yeah! I'm interested.
1/4" on center. Stand is 3/4" above the stove.
Try burning a piece of mesh over the top of your burner right in the sweet spot of the flame. Don't use a pot!!!!!
You may not be getting enough oxygen in the equation.
Got any 1/4 inch galvanised, try it with same burner/pot combination.
Skidsteer
02-16-2007, 19:14
Try burning a piece of mesh over the top of your burner right in the sweet spot of the flame. Don't use a pot!!!!!
You may not be getting enough oxygen in the equation.
Got any 1/4 inch galvanised, try it with same burner/pot combination.
It's not the fuel, or the oxygen, or anything but the metal in the stand.
Here's what the bottom of the Heineken pot looks like after at least a dozen burns using that stand.
Skids, show us the burner and potstand. Burner inside potstand, no pot, top view.
Skidsteer
02-16-2007, 21:36
Skids, show us the burner and potstand. Burner inside potstand, no pot, top view.
Okay.
I'll throw in some bonus pics as well.
Keep at it till smoke stops
Okay.
I'll throw in some bonus pics as well.
With everything I read here about alcohol stoves I had to build one just to see what the fuss was all about. I used these instructions: http://www.pcthiker.com/pages/gear/pepsistoveinstruct.shtml
When I finished the stove I wanted to test it so I placed a piece of flat wire cloth over the top of the stove supported by wood blocks from the sides. My wire cloth was nearly touching the top of the stove. the area of flame passing through my screen was similar to that shown in the photos above. My screen glowed red and became covered with soot.
I continued to experiment by raising the screen in 1/2" increments to find the hottest part of the flame. At about 1-1/4" above the stove I determined that my water boiled quickest on a given amount of fuel. Also, at that height there was no soot on either my pot or the wire cloth. I used this information to build a pot support stand out of copper flashing. There is never any soot on my pot, pot support screws or the inside of my copper stand.
I think the problem discussed here in neither the fuel nor the type of metal the wire cloth is fabricated from. My feeling is that the flame passing thru the screen near to top of the stove is relatively cool and rich which would result in carbon accumulation. The fuel/air mixture so close to the stove would be incomplete and thus very rich.
You could test my theory by doing a test burn with samples of the wire cloth positioned at different locations in your flame.
This "stove thing" is addictive. Its impossible to walk through Home Depot without looking at all those wonderful stove parts.
Excellent point and you're right!!
Skidsteer
02-17-2007, 09:49
The same stove with the same fuel using a mesh stand from galvanized metal doesn't produce the sooting. Same thing with an aluminum stand-no carbon. Just this 'stainless steel'.
...it's not the fuel. Yellow Heet does the same thing. As I said earlier, the carbon is only a problem with this stand and no other.
I'll try the torch solution when I get a chance. I have a feeling the S.S. is a poor grade and there lies the problem.
...........
I think the problem discussed here in neither the fuel nor the type of metal the wire cloth is fabricated from. My feeling is that the flame passing thru the screen near to top of the stove is relatively cool and rich which would result in carbon accumulation. The fuel/air mixture so close to the stove would be incomplete and thus very rich.
You could test my theory by doing a test burn with samples of the wire cloth positioned at different locations in your flame.
.
I agree with you STEVEM, when I look at this photo the burner (http://www.whiteblaze.net/forum/attachment.php?attachmentid=1418&d=1171676197)looks like it wants and can burn alot of fuel fast. Its getting a good oxygen mix necessary for a good burn. As soon as the pot is lowered over the flame and pushes it downward to the top of the potstand it becomes starved for air mix. The burner is hot and vaporising fuel big time, but not getting the air mix needed for a complete burn.
But, Skids you say it works with galvanized of the same configuration. That blows my mind:confused: . Make a smaller bird feeder with the remaining mesh:sun
Get the 1/2 inch hardware cloth in stainless and your troubles should disappear.
Good Luck on your project and thanks for the great photos.
The soot or black deposits can come from only two places:
1. The fuel.
2. The S/S wire mesh.
Carbon within metal can become overheated and actually become a fuel. To see this fluff up some fine steel wool and light it with a match. (do this outdoors).
If the flame was hot enough to extract the carbon from the S/S I believe the screen would be consumed by the flame. Overheated stainless steel will experience carbon precipitation which appears as permanent blackening or blueing of the surface. This is not soot, and will not rub off.
One difference between carbon steel, aluminum and stainless steel is thermal conductivity. Stainless steel is the least conductive of the three, therefore the temperature of the material within the flame zone would tend to be higher than the galvanized or aluminum mesh. Perhaps this high temperature surface is somehow drawing out the carbon from the fuel/air mixture.
Loose carbon black soot is almost always the result of inefficient or incomplete combustion. If the soot you see is similar to that in the exhaust pipe of a poorly tuned engine or the inside of a wood stove I feel certain that it is coming from the fuel.
oldfivetango
02-17-2007, 11:47
Bottom line -- if there's any yellow in the flame, there's carbon being produced. If the flame is pure blue, it's clean.
Yup-that's the test some of us use for determing if
moonshine is of the proper grade for consumption!
Cheers and drink up!
Oldfivetango
Skidsteer
02-17-2007, 13:54
Problem is solved. Ten more minutes of careful torchwork(thanks mrc237!)and no more soot.
Zelph, the stove pictured is not what I would consider a particularly fast burning stove, but I like it pretty well. 15 ml will boil 2 cups in 8-9 minutes; Burnout in another 1-2 minutes. Weighs 5 grams.
Thanks to everybody for the interesting info.
Bottom line -- if there's any yellow in the flame, there's carbon being produced. If the flame is pure blue, it's clean.
That's fascinating. Is it a variant of fuel? Or can a general fuel by combusted fully under the right conditions?
Pacific Tortuga
02-17-2007, 17:55
Carbon depends on the series of SS your using.
400 series is magnetic and contains carbon.
300 series is Not magnetic and does not contain carbon.
Carbon depends on the series of SS your using.
400 series is magnetic and contains carbon.
300 series is Not magnetic and does not contain carbon.
Thats pretty close to correct, though all stainless steel contains some carbon. The elements that do vary considerable between grades of S/S are nickel and chromium. The grade of stainless probably has no importance for an individual fabricating a stove part for his own use. Use what you can find.
I spent many years working in the commercial kitchen equipment industry. Most of the S/S used in commercial kitchen equipment will be type 304 non-magnetic. Products sold for residential use will usually be type 430 magnetic. Products used in dairy, brewing, chemical and pharmaceutical applications will usually be type 316 non-magnetic.
Finding a small piece of stainless steel to use for a home project can sometimes be difficult. One good source is your local kitchen equipment fabricator (check the yellow pages) They will have lots of what you need (light gauge sheet, perforated and wire cloth) in their scrap barrels. Sometimes they'll even give away small pieces of scrap. I often had craftsmen and homeowners stop by the shop looking for small pieces of metal.
Another good source for material of all types is http://www.mcmaster.com/
I often needed to purchase small quantities in special materials from them, and I think they will accept credit card orders from individuals.
The thickest gauge S/S which can be worked with common handtools is probably 20Ga. (0.0375") thick. Buy your drill bits and hacksaw blades from an industrial supply house, and tell them you are working with stainless steel. Home Depot tools and bits will usually not work on S/S.
Bloodroot
02-18-2007, 13:08
I work as a safety director for an Engineering/Construction group who primarily metal fabricates all work in house. In regards to stainless, we use 316 and hasteloy fittings. Anyhow, OSHA imposed a new standard on welding/fabrication of stainless steel that much resembles the same laws as asbestos. Basically people working on and around heating of stainless steel are getting exposure to hexavalent chromium, a known human carcinogen. You don't hear much about it now, but in the near future this will be very hot topic just like asbestos and lead-based paint.
Two Speed
02-18-2007, 18:27
. . . Two Speed, Is it 1/2" wire mesh? Yeah! I'm interested.Sorry it took so long to get back, but a little backpacking interfered with sitting at the computer and talking about backpacking. Ahem, having gotten that off my chest, no, 1/4", but I've used it for several pot stands and it takes the abuse just fine. Shoot me a PM if you're still interested.
Skidsteer
02-18-2007, 18:50
Sorry it took so long to get back, but a little backpacking interfered with sitting at the computer and talking about backpacking. Ahem, having gotten that off my chest, no, 1/4", but I've used it for several pot stands and it takes the abuse just fine. Shoot me a PM if you're still interested.
PM sent! :)