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Swede
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New Spot Welder rig
I've tried both TIG welding and spot welding to create anodes and cathodes of CP Ti and MMO in various sizes, and it turned out spot welding was
infinitely easier and more effective than TIG, unless you have a very high-end TIG machine that can create a stable arc of just a couple of amps.
Anyway, my old spot welder had been made from a rewound transformer, coupled to a pair of clamp arms and a timer + foot pedal.
I was making up a bunch of MMO + Ti anodes, and my old homemade welder just wasn't hacking it... not enough current. I decided to try Harbor
Freight's 115V spot welder. Not the cheapest, but the results are spectacular compared to my homemade welder.
I took the harbor freight welder and modified it extensively. As it came out of the box, it was a handheld clunker with a simple ON-OFF switch under
the handle. I pulled the switch, found it was simply 115V for the primary of the transformer, and routed them instead to a timer-controlled solid
state relay of 40 amps.
The handle was modified, and the welder itself clamped to the same aluminum plate used earlier.
This setup is AWESOME. If $$ is not a big object, and you want to do a bit of spot welding for technochemistry, this is a decent way to go. A 1/2
second weld time easily welds MMO mesh to Ti sheet of 1.3mm thickness, and I have no doubt it'd do several mm if needed.
The timer (red thing) is a "National Controls Corporation" model TMM-0999M-461, set to "1-shot" function on the control face.
Here is a basic diagram for this timer when coupled to a home-modified transformer. To adapt the HF welder, the 2 wires in the handle are simply
attached to the SS relay output side.
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dann2
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Hello,
Nice job Swede, as always. I have a 180 amp (stick) welder and I must rig up some sort of a spot welding attachement some time. What metals can you
make the actual 'pincure tips' from. Does it have to be Copper. Wonder would very thick steel? do or perhaps use steel bars with Copper pieces on the
ends where the welding actually takes place. I have no long large Copper bars but would have two short bars.
Some stuff here
http://pubs.acs.org/doi/abs/10.1021/es970578h
about attacking marine bacteria with TiN electrode. The highest Voltage used was 0.8 Volts (afaics) versus AgCl (how much 'applied' Voltage, as we
would say, that related to I don't know but it is low as they say it avoides the release of Chlorine. Is this to save the electrode?
On a different note there are two papers in the reference section in "Wanted References and Needed Translations (5)" regarding Barium Chlorate and
Perchlorate making that may interest some here. Posts are dated 31 July 2009.
Dann2
[Edited on 1-8-2009 by dann2]
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watson.fawkes
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Quote: Originally posted by dann2  | | What metals can you make the actual 'pincure tips' from. Does it have to be Copper. Wonder would very thick steel? do or perhaps use steel bars with
Copper pieces on the ends where the welding actually takes place. |
The magic keyword for searching is
"resistance welding". The AWS has a handbook on the subject.
The heuristic to think about this is that each thickness of metal is a resistor and also each metal-to-metal junction is also a resistor. Heat
develops in the areas of high resistance. That means heating steel with a steel tip is sure to weld the tip to the work. You use low resistance tips
(copper) in order that the resistance heat be generated in the work piece.
Paradoxically, you use tungsten tip buttons to spot weld copper. Here the heat is generated in the tip and transferred to the work. The weld bead is a
different shape. This technique works because the melting point of copper is lower than that of tungsten, and so you tend to melt the work rather than
the tip.
You can use steel to hold the tips up mechanically, but if you do, it's best to use a separate current conductor to avoid long cooling-off cycles.
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Swede
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WF is correct. I've tried Copper, tungsten, and brass. The latter two did not work well. The brass did work, but left behind touches of zinc slag,
and the tips tended to stick to the work.
Copper bar can be a pain to work with, let alone find. It usually has to be ordered. For this sort of work, the tips also need to have a cross
section of maybe 1/8" or 3mm, and an included angle of 90 to 120 degrees.
Solid Ag would probably work very well!  Whatever is used, the resistance
needs to be as low as possible, or they will heat ferociously.
Edit: I also noted the AC voltage of the arms on this rig are 1.6 volts vs. 4 volts for my homemade job. In the transformer, fewer secondary winds =
lower voltage = greater current. On my homemade rig, if I had taken a couple of the secondary winds off, I might have been able to jack the current
up a bit, but the secondary, of #4 stranded copper, was already heating up too much. It couldn't have carried more current. The transformer was just
too small.
Hacking the HF spot welder is not the cheapest way to go, but it does work very well indeed and will save a lot of time.
[Edited on 3-8-2009 by Swede]
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Swede
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Testing for nitrites in a Lead Dioxide plating bath:
One of the problems seen by many is that the useful life of a lead nitrate/HNO3 bath to plate LD appears to be limited. Even when the lead is
replenished, for some reason, plating quality deteriorates. This is bad, obviously - a few liters of Lead Nitrate solution is both a hazard and
expensive.
One proposed contaminant was nitirites. I picked up a test kit for nitrites (aquarium) that appears reasonably sensitive... first test was for
interference from nitrates. A solution of KNO3 in distilled water showed zero nitirite. Next, a sodium nitrite solution was tested with known
quantities of nitrite, and the kit picked them up just fine.
I tried testing some used plating solution for nitrite with this crude kit, and it showed zero. This does NOT mean there are no nitrites... but it is
encouraging. The possibility exists that the ionic species hash that is used LD plating liquor interferes or otherwise prevents the kit from
detecting nitrites.
I do not know the mechanism of this particular kit. I need to do a bit of study and perhaps come up with a reliable test to see if nitrites ARE a
problem when plating LD.
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dann2
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Hello Swede,
This is good! I purchased an aquarium Nitrite test kit some time ago but did not get time to test some solutions. Still have to buy some Nitrite. It
is sold as an engine anti corrosion additive for vehicles.
If you add a tiny amount of the Nitrite to a small quantity of Lead Nitrate plating solution they you can see how good the test kit is for our job.
Start with a tiny amount.
There may be Nitrites in the (your actual solution that you tested) plating solution when it is been used and soon after. Nitrites get oxidized by air
back to Nitrates. How long it takes I have no idea (assuming what I am saying is indeed correct). One guy suggested bubbling air through used plating
solution to get rid if Nitrites. Guess the O2 of the air is going what the H2O2 does in some of the patents.
You could even try destroying the Nitrites (H2O2 or air) after you test for them (after adding the Nitrites and hopefully getting a positive test
using your kit).
Currently working on a pump for pumping Lead Nitrate solution. I have a peristaltic pump that will do the job in conjunction with a timer but I am
trying to set up a pump + timer that uses air going into a bent tube for to pump the (small amounts) of plating liquid.
My thinking is that the air going through the solution in the pipe will keep Nitrites at bay? It makes a very relaxing sound too!! Currently testing
with an Ammonium Nitrate solution (saturated, density approx. 1.3, similar to plating solution). Its inclined to bung up sometimes. I think it's the
AN solution evaporating when its gets warm (70C) and going solid somewhere. This may happen with plating solution too, so may need to use peristaltic
after all.
Need to get a move on.
Dann2
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Swede
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I think movement of air through the solution would be a good way to go, at least as a start, being gentler than peroxide. I don't know if a
peristaltic pump alone will provide adequate contact between the plating sol'n and atmospheric oxygen. You could always use a bubbler, but I would be
very hesitant to use one outside of some sort of sealed chamber due to misting. I definitely need to get going some more.
I've continued my examination of the Laserred MMO mesh. I've got quite a bit, and overall, I am very pleased with it. There are some areas of
contact where the Ti is slightly exposed, but you can easily create 6 3" X 5" MMO anodes from one sheet. I set up a jig on my bandsaw and ripped off
that 90 degree "L" portion with little fuss on several sheets.
The brown smut is ever-present. Some sheets have more than others, but they all have it to some extent. I reported earlier that HCl cleans it up
well. I did some more experimenting, especially with an ohmmeter. On an untreated sheet, the surface resistance can be high. I've measured it in the
20 to 30 kilohm range even on portions of the sheet with no smut. But an HCl pickle not only removes the smut, it apparently strips some other
contaminant, not necessarily visible, and the pickled sheet shows near zero resistance, in contrast.
I took 6 sections of the "L" I removed, and pickled them all for various amounts of time in 16% HCl. I took a seventh piece, and pickled it for 6
hours in 32% HCl. None of the strips in the 16% HCl cleaned up nearly as well as the one in 32%, and as far as I can tell, even the 32% cannot touch
the actual MMO; it simply cleans it very well.
On the left is a piece pickled for an hour in 16%... the one on the right, 6 hours in 32%.
The 32% actually only needed about 15 minutes to clean, but I left it in for a long time to verify that no actual damage will occur. The surface
resistance of the 32% piece was nil, and it spot-welded instantly with no scraping needed. Conclusion - pickle away in 32% hardware store muriatic
all day if you want. It definitely does a good job.
The HCl will become brilliant yellow. Use caution - I have no idea what this contaminant is, and it would be wise to treat it as possibly toxic.
Handle uncleaned sheets with gloves, and dispose of the used HCl in a responsible manner.
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Swede
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dann2, I realized I didn't really address your nitrite question very well. My problem now is that my workspace is about 130 degrees F, literally.
Every operation that requires a decent clear space, or is potentially hazardous, such as working with the Lead Nitrate plating bath, is on hold until
the weather changes. I cannot describe how hideous it is. The best I can do is putter until my shop cools down.
If nitrite is a short-lived species that is created during the actual plating process, any serious experiments for me will have to wait a bit. The
best I can do right now is see if the aquarium kit can detect added nitrite to used plating bath liquor.
Since nitrite is exceptionally poisonous to fish, the kit is designed to be fairly sensitive. The kit I bought is by "Aquarium Pharmaceuticals" and
is designed to detect as low as 1/4 ppm. Interestingly, the base color (0 ppm) is an aqua color that is identical to the color of my particular
plating bath, which contains nickel nitrate. In other words, even before the reagent is added to the sample, the sample starts with the same color as
the "0" scale. Adding the test reagent doesn't appreciably darken the color. What I'm trying to say (badly) is that even with nickel nitrate (added
as a grain refiner) I am hopeful the kit will work. But given the acidity, the strong lead nitrate presence, it will be hard to say if it will work
until additional tests are done.
I need to scour the web and my own book resources a bit and see if I can find the basis behind the test kit. If we know what the test reagent is, we
can determine if it will be effective. If it's not, we can possibly find one that is. I have a college text named "Quantitative Analysis". I'll see
if there's anything in there on nitrite.
[Edited on 8-8-2009 by Swede]
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dann2
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Hi Swede,
The test kit I have is exactly the same as yours!
There is a test at this link using Sulphuric acid and Ferrous Sulphate.
http://en.wikipedia.org/wiki/Nitrite_test
but I reckon it would be useless as when you add Sulphuric acid, Lead Sulphate will ppt. I think the Nitrate ion will not interfer as per reading on
the next link below at where it says: 'Parameter Overview'
Hach do a Nitrite test at this link:
http://www.hach.com/hc/browse.parameter.list/PAR114/NewLinkL...
Another test kit here says:
______________________________
CHEMISTRY OF COLOR REACTIONS
Nitrite reacts with two acids in the Nitrite Powder Pillow Reagent (sulfanilic and then chromotropic) to form a red complex whose concentration is
directly proportional to the amount of nitrite originally present. By measuring the intensity of the reddish complex with the color comparator, the
concentration of the nitrite is easily determined.
______________________________
Perhaps that's what is in all Aquarium kits?
Another test (attached picture) from link below:
http://www.springerlink.com/content/p425v73427852116/
Test strip below:
http://www.sigmaaldrich.com/catalog/ProductDetail.do?D7=0&am...
You can make Sodium Nitrite using Lead Metal and Sodium Nitrate. Melt Lead and stir in Sodium Nitrate. Other product is Lead Monoxide (Litharge). Now
let me see, where did I see a useful idea for using that stuff...............
If you read patent US 5558772 it says that Nitrobacker Agilis (the little bugger ) which in present in air converts Nitrite to Nitrate but that bacteria is hardly able to operate in a plating solution.
This post is becoming a bit of a ramble..........
Regarding the pump I was setting up to pump plating solution from one beaker into another beaker, I have given up on the air driven type. Apart from
the splattering that was occuring (it could be controlled using a cover) the air pipe is inclined to plug with crystals from small amounts of solution
what would make it's way into the air pipe and then dry off with the stream of air going past (and deposit the crystals). This type of pums is not
suitable for pumping solutions IMO. Only simple liquids. So I am onto the Peristaltic and timer set up. A syphon returns the fluid back to the
original beaker. I am using a conc. solution of Ammonium Nitrate, density about 1.3.
130F THAT'S hot.
Dann2
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Bikemaster
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I have a problem with my mmo anode. I bought it 10 month latter from north star pyro, and the anode is already dead...
Last time i go see my chlorate cell, it was full of rust (i use high quality stailless stell and sometime is can make black stuff, but this time it
was really the orange color rust). When i pull out the electrodes from the mess, the anode has a line of gray color just at the level of water when
the anode was in the cell. The gray line is 0,5 cm wide. I am pready sure that it is TiO.
Cell specs:
- 7,5 volt
- 3,25 amp
- 2L
- mmo anode
- stainlless stell cathode
- no ph control
- no temperature control
p.s.: The anode was running for 8 month in those condition. But in the last 3 month, i let the cell run up to the end ( well under the 100g/L of KCl).
beffore that, i was getting the kclo3 out and refressing the cell all week.
Now, I have 2 question. First, can this anode can always be turn to a lead dioxide anode, and can i use this anode as a cathode???
I pay 80$ with shipping for this anode, it is why it should be nice to reuse it
thx
[Edited on 12-8-2009 by Bikemaster]
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Swede
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Your voltage seems high, and current seems low. Normally, 7.5V would create 50+ amps with a 2 cm electrode spacing, given a power supply capable of
such current. High voltages can cause problems with this process, and make anode erosion more likely.
It's hard to tell from the photo... it does look like MMO has been stripped from the area directly below the welds, but the bulk of it still appears
to have MMO coating.
If the silvery area is stripped of MMO, then yes you have bare titanium which creates a protective oxide under normal circumstances, and while it
can't make chlorate, at least it should not disintegrate.
If the silvery color is some sort of coating OVER an underlying MMO, then perhaps it can be removed with gentle brushing (toothbrush) and/or acid
pickling.
If it's gone, you've still got a significant percentage of MMO on the bottom, and it should still make chlorate. Have you tried it with fresh
electrolyte?
On the cathode - I know there is some question as to hydrogen and other problems with titanium, but I am still convinced that commercially pure
Titanium is the best and most cost-effective cathode for a cell. Unless it is abused, a CP Ti cathode seems to last forever. I even go to the
trouble of using only commercially pure titanium, rather than the titanium alloys. CP Ti is easier to cut, weld, and work, than Ti alloys, and I
think it creates a cleaner process. Yes, SS works, but every time the electricity is OFF, I think you are having measurable erosion and the cathode
is probably dumping undesirable ions into the liquor. It is difficult to work with a cell with the power on all the time, and as soon as the power is
off, there's no longer any cathodic protection. I know factories use SS for low cost, but they also have much more control over the process than we
do.
@ dann2 - what little research I did on nitrites and their detection so far all point to the formation of a highly visible azo dye, with the color
intensity corresponding to nitrite levels. It would be a hassle, but it might be possible to "clean" a sample first by precipitating the lead and
perhaps neutralizing the nitric acid, with the idea being the creation of species that will not interfere with the test, while at the same time not
adding to, or dropping, the nitrite level in the sample. It might be as simple as adding magnesium sulfate in excess to drop the lead, perhaps lye or
a carbonate to neutralize (if needed) and decanting or pipetting the resultant liquid for a nitrite test.
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dann2
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Hello,
What power supply are you using. Would it have failed and was putting an ac into the cell so that the SS 'cathode' will be eroded big time (it will
be an anode)?
What are the dimensions of the Anode. If you know that you can tell the current density on the Anode. It is really the current density on the surface
of the Anode that counts for erosion and not the Voltage accross the cell. (ignoring low Chloride levels etc)When the Voltage accross the cell is
high(ish) (as your cell Voltage is) it can be simply caused by bad connections, too much spacing between Anode and Cathode or skinny wire etc. This
does not really matter as it only wastes power. If the current density on the Anode is high (too high) then that will require an excessive Voltage
which can be an indication of problems. (too high cd on Anode).
We dont really know how long MMO lasts in a non pH controlled cell with unknown Chloride levels + varying (too high) temperatures + high/unknown
current density densitys on Anode etc etc. Perhaps 10 months in good. Perhaps that's all you can expect. Low Chloride levels absolutely eat Graphite.
If using as a Lead Dioxide Anode substrate try and find out what areas of the Anode still have MMO on them. Lower the Anode into a cell slowly and
see what areas of the Anode have some gas coming from them. No gas = no current coming out of that Anode area = Ti Oxide coating (no MMO).
If most of the Anode has MMO then it should be OK as a substrate. You could always coat with Tin Oxide................
Dann2
Dann2
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Bikemaster
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Not deap enough... i think is one of my problem. because, in winter they have no really evaporation, but in summer, the water evaporate much faster
and sometime, only the midle of the anode is in the water.
An other think, now, with multimeter a can really see how much amp that pass in my cell. And i don't now why but i got more that the maximum of the
power supply. For exemple, my power supply is rate max 3A but i can get up to 4A (not just for the first few days). Can this be bad for my power
supply or my electrode???
And yes, ss always put some inpurity. The water always turn to a light green and some blach stuff drop in the cell, but not alot.
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dann2
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What are the dimensions of the Anode?
Have you any Copper wire connections that are causing the Green colour?
Dann2
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Bikemaster
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anode : 2x6
catode : 2x6
and yes the copper part that touch the electrode always turn green. i just sand this part between all batch.
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User
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Does anyone know any decent suppliers for MMO anodes located in europe?
The ones i found so far are so darn expensive that i might be as well of with Pt wire.
What a fine day for chemistry this is.
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dann2
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Hello,
@Bikemaster
I presume it's 2 cm by 6 cm. Thats a surface area of 2 x 6 x 2 = 24cm squared assuming a flat plate.
Looking at the picture of the Anode I am going to guess that the Anode has approximately one third (it may be less) of this area = 8 cm squared.
Running the Anode at 3.25 Ampers gives a current density of 400 mA per square cm.
That's considered high for MMO. Just goes to show how tough the stuff is.
I presume you have one Cathode and it is to one side of the Anode.
You could cut you Cathode in half and put each half on either side of the Anode so that current distribution on the Anode is more even. It is hard to
guess how uneven current distribution on the Anode is when the Cathode is on one side only. The Anode will be inclined to wear more on the side
nearest the Cathode because of the higher CE on that side.
@ User Try Googling for Corrosion control companys, Cathodic protection companies, or of course the water chlorination people (swimming pool
supplies).
............there's always Graphite with acid dripping into cell............
Dann2
What a fine day for the PMMMO this is!!!
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Bikemaster
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oups... it is 2x6 inch for the anode and the cathode.
But the idea of making 2 cathode is not bad. I will try it.
thx
[Edited on 28-8-2009 by Bikemaster]
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dann2
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Hello,
There is definately a conspiracy going on on the board to keep the dimensions of that Anode from me!!
I attach a screen capture of you last post Bikemaster. Whatever character you put in for inches? or centimeters? has come out my end as the word
'Text' in bold (to boot!) 
Did you mean inches or did you actually mean to write 'Text'. If so I don't understand what you are saying.
Cheers,
Dann2
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iHME
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It clearly reads as inch in my end.
"oups... it is 2x6 inch for the anode and the cathode. "
It\'s a catastrophic success.
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dann2
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Thanks for that.
'inch' is showing up OK in both post now.
Quite an big Anode then, low current density.
Dann2
[Edited on 29-8-2009 by dann2]
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dann2
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Hello,
Going back to the topic of making Perchlorate with a Graphite rod in a cell with a divider...
It was suggested to use a 'Lambskin' condom. I took this to be (literally) a piece of Lambs* skin around the Graphite (like a condom).
Granitstaterecovery (name of poster) was referring to a 'Lambskin' rubber (as in, how would I put it, a dick cover... LOL).
From a reputable publication, page 18, from here:
http://www.thevespiary.org/Naf1/Fester/AdvTech.pdf
I quote:
"netic stirrer. Clip a well scrubbed Kling-Tite Naturalamb rubber
in one side of the beaker, and put a piece of lead about viinch
in diameter, and a few inches long, inside the rubber. On
the opposite side of the beaker, stand up a one ounce ingot of
palladium Using alligator clips, make contact with the ingot,
and with the piece of lead. Next pour most of the dilute sulfuric"
The Author is not making Perchlorate etc btw but he mentions the divider. Will have to try it for Perk. Perhaps the cell conditions will be too harse
in a Perk. cell.
Will any condom do or does it have to be a 'lambskin'. Not too well up in condom varieties. I find it hard to belived they will allow electricity
through.
edit:
FFS, I Googled 'Lambskin' and it come up first with the word Condom after it, with a hits rating of 30,000.
It appears that they are made from Lambs intestines.
Brings a whole new meaning to the threat, 'I'll have your guts for garters'........
Now where can I get a dead sheep. Hope, when and if I do find one, that it does not ravish me. It's happened before you know......
Good Night
Dann2
*(an in: meaa, meaa, bleat, bleat, four legs good, two legs better. four legs good, two legs better. four legs good, two legs better, four legs good,
two legs better.)
[Edited on 3-9-2009 by dann2]
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barbs09
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I guess modern science has produced better membranes since the use of lambskin but the use of what’s at hand (lamb skin intestines??) is what we are
all about. Pig intestine skins are widely used as sausage outers and may have the same characteristics.
I find it no surprise that such material conducts electricity/permits ion mobility after all didn't life evolve intestines for the diffusion of water
and ions out of the poop shoot into the blood stream?
I will watch the development of this perchlorate route with interest
Enjoy catching your lamb -ask one of the ozzy members if they have any spare Velcro gloves (couldn't resist!!!)
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Swede
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I finally figured out a way to adapt a round Ti tube as an electrode shank, which gives one the huge advantage in a secure (yet maintainable) setup
using a stock PVDF compression fitting.
In a nutshell: Flatten the tube at one end, weld to the electrode. At the other end, install a plastic plug inside the tube, then hammer in a brass
or similar threaded fitting for the electrical connection.
Flat straps are a pain - here is a way to use a round shank for many electrochemical processes.
The MMO pictured is the "Laserred" material after pickling in HCl. Laserred is not currently offering any more on eBay. It was a tremendous
bargain... maybe he'll be back.
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Bikemaster
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I got 3 of those mmo from lassered... it was a real good deal.
swede, i got some question for you. Can i use a simple grider to cut the piece in pieces??? and can i use a simple welder to weld the handle (with a
rod for weld titanium).
and those cut and welding will let some titanum expose. Will it make proble to the anode.
thx
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