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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 20th Oct 2018, 4:16 pm   #61
AC/HL
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Default Re: Don't try this at home...

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Times change
They do. This is an open forum, and in today's security aware times, discussion of explosives, even of the "mischief night" variety is likely to get unwanted attention from several directions.

Open threads like this inevitably drift from the original purpose (workshop hints) but not too far please.
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Old 20th Oct 2018, 4:31 pm   #62
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Default Re: Don't try this at home...

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Quote:
Originally Posted by Richard_FM View Post
Times change
They do. This is an open forum, and in today's security aware times, discussion of explosives, even of the "mischief night" variety is likely to get unwanted attention from several directions.

Open threads like this inevitably drift from the original purpose (workshop hints) but not too far please.
Sorry if this was unsuitable for quoting, I just thought it would be worth mentioning to show how flippant the use of dangerous chemicals was in the past.
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Old 20th Oct 2018, 4:48 pm   #63
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Default Re: Don't try this at home...

Sorry Richard, that was just a convenient comment, not meant as a reference to your post in particular! There are inevitably such hazards in workshops, some unavoidable, some not.
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Old 20th Oct 2018, 7:39 pm   #64
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Default Re: Don't try this at home...

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'sometimes the experiment is rather violent, the substance blowing up rather than burning'.
When I was around 12, I had a Merit chemistry set. Most of these were fairly mild in their native form but add-ons were readily available. I found an experiment in a boy's book on how to make coal gas. Basically a small amount of coal dust heated in a test tube with a stopper in the top. Fairly precise instructions were given about the heating time and to my delight when the stopper was removed and the burner was held to the top, a pop resulted with a flash of flame.

Greatly inspired by this I decided to have another go with more coal dust and a larger test tube. We used coal in those days so there was more than enough coal dust in the coal scuttle to make a nice little pile in the bottom of the tube. Plenty of heat and a larger stopper.....and in this case I fitted the test tube into a holder. Having removed the heat and the stopper and applied a flame to the top (on an extended holder).....the resulting bang blew the bottom out of the test tube since the flame produced was also correspondingly larger and went back down inside the tube where presumably the concentration a gas was highest....it did make a bit of a mess since the unburnt coal dust went all over the table.

Great fun at the time but much easier to make hydrogen though. I loved the bright blue flame that produced....

I doubt that boy's books would be printed today that suggested how to make combustible gas...
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Old 20th Oct 2018, 7:54 pm   #65
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Default Re: Don't try this at home...

Many years ago I was given a book of experiments that could be performed at home. One of them was how to make hydrogen gas, when even I was young sounded potentially dangerous.
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Old 20th Oct 2018, 8:16 pm   #66
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Default Re: Don't try this at home...

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...make coal gas. Basically a small amount of coal dust heated in a test tube...
That was one of my favourite experiments! Over time, I developed a more sophisticated version where the gas bubbled through a U-tube filled with water to clean the gas. I managed to produce a small flame, no bang luckily. The only problem was that the test tube used as the retort was inevitably ruined and couldn't be cleaned out afterwards.

I think my first chemistry set was by Merit. They also made model steam engines, and I had one, although it wasn't as good as those made by Mamod. Anyway, I digress... I well remember the introduction to the instruction book that came with the chemistry set. It started: "On being presented with a chemistry set, the first thing every boy wants to do is make a foul smell..."!

Little changes.
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Old 20th Oct 2018, 10:45 pm   #67
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"On being presented with a chemistry set, the first thing every boy wants to do is make a foul smell..."!
Did that as well! That one really didn't go down too well with the rest of the family. Even after all traces of the offending mixture had been forcibly disposed of despite my protests....the smell seemed to linger in the house for weeks.....
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Old 21st Oct 2018, 8:43 am   #68
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Default Re: Don't try this at home...

There's a balance of risks involved in all these things, and as more becomes known, that balance changes.
I recently read that electric shock is now believed to be a predisposing factor for motor neuron disease, so it's no longer a simple case of 'I got away with that' - the effects may be seen many years later. The same principle has proved to be true for a number of substances and activities discussed here, and no doubt there are many more waiting to be discovered.
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Old 21st Oct 2018, 9:20 am   #69
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Default Re: Don't try this at home...

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I recently read that electric shock is now believed to be a predisposing factor for motor neuron disease.
There is an article about this in New Scientist
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Old 22nd Oct 2018, 9:57 am   #70
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Default Re: Don't try this at home...

In that case I should have it but haven't - so far. Working on valve TV's and radios gave most engineers of my time several shocks a day, so did transistor TV's to a lesser extent, multiply that by 50 years .....

On the matter of experiments, when I was a kid I tried producing 'water gas' from a glass 2v accumulator, I connected a small tube to the vent and attempted to light the end while it was gassing, there was a deafening explosion and pieces of glass embedded in the walls of my shed, not in me fortunately.

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Old 22nd Oct 2018, 11:16 am   #71
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Default Re: Don't try this at home...

The gas from a venting lead acid battery is a perfect explosive mixture.
I was once shown a car battery where the mechanic had disconnected the charger while it was still switched on. The top was blown clean off the battery.
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Old 22nd Oct 2018, 11:55 am   #72
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Default Re: Don't try this at home...

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I recently read that electric shock is now believed to be a predisposing factor for motor neuron disease.
There is an article about this in New Scientist
This interesting idea seems to be of immediate concern to those of us who, over a lifetime, have experienced a few 'belts'. Maybe that's all of us! So I looked a bit further.

Reading the article suggests that the kind of 'electric shock' considered in this theory is the type producing severe trauma, and possibly nerve damage. For example, one case involved a lightning strike on to a climber's ice axe. More recently, the Daily Mail and Daily Express seem to be expounding on these theories. No further comment necessary!

The NHS website comments:

"This was a prospective cohort study. Cohort studies follow large groups of people to see what happens to them over time. While this can be a good way to spot patterns and links between factors, cohort studies cannot prove that one factor (such as extremely low frequency (ELF) magnetic fields) causes another (such as amyotrophic lateral sclerosis (ALS))."

There seems to be some muddling between electric shocks, with their well-known risks, and low frequency magnetic fields, with little established evidence of risks. There's also an assumption that the welding and electrical contracting trades are exposed to high intensity fields, which seems to me unlikely when compared with some other professions.

Overall, causes of motor neurone disease (medical term ALS) remain a mystery, and an important one to solve, but, from the evidence mentioned, there seems little reason to think that electric shocks make a contribution.

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Old 22nd Oct 2018, 12:13 pm   #73
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Default Re: Don't try this at home...

Thank heavens for that last line, I thought I was running on borrowed time.
Never had a traumatic shock, just the odd violent muscle contractions.

I have noticed that post a good tingle, usually off DC, life seems brighter somehow.......................................
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Old 23rd Oct 2018, 10:36 am   #74
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Radiation was another scare with early TV's, it was thought by some that watching TV could be harmful but most of the radiation comes from the gun end of the CRT and I'm sure many of us have spent hours sitting on a stool directly behind the back end of the tube but I have never had of any ill effects.

Early TV's with mains EHT only ran at about 5 kv, when we got colour that was 25 kv but no concerns apparently.

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Old 23rd Oct 2018, 1:33 pm   #75
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Default Re: Don't try this at home...

I remember manufacturers of early colour sets (with PL509, PD500 and GY501 valves in
a shielded compartment) recommended viewing these valves in operation through lead
glass as X-rays were emitted.
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Old 23rd Oct 2018, 6:42 pm   #76
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Default Re: Don't try this at home...

A lot of people have 'got away with' handling dangerous chemicals, doing unsafe acts, etc.

Removing these hazards does make the world a safer place, but it makes it more boring too.

I've got a couple of cc's of mercury in my collection of metals, in a jar in my bedroom - no immediate use for the stuff, but I'm not worried. Metallic Mercury isn't too bad as it is rather unreactive (people have been asked to swallow some, to cure a blockage!), however the compounds really have ill effects on the human body. And yes, I've got metallic sodium and potassium too.

Effects of carbon tetrachloride on the liver are known. I've handled the stuff - used to use it for cleaning projectors, with a toothbrush, last bottle I bought was probably 1982, from Boots chemist in Headington, Oxford. I wouldn't willingly use it now though.

I've never handled hydrofluoric acid. My mother has, though she was well instructed in the precautions to take - which include having a spill kit and antidote immediately to hand.

It's easy to be blasť about us all having survived! I showed my friend and her 12 yo daughter recently how to make flash powder with aluminium, sulphur, and potassium permanganate, setting it off with a drop of glycerine. Making nitrogen triiodide is great fun too and I would willingly give a gram or so of iodine crystals to a sensible teenager to have a go. But not my whole jar! I wouldn't attempt to saw up asbestos myself, no way. Many people are immune, unfortunately if I happen to be one who isn't, by finding out it's already too late...
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Old 23rd Oct 2018, 8:11 pm   #77
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Well you learn something every day, i didn't know Carbon Tet was hazardous..
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Old 24th Oct 2018, 12:16 am   #78
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Question Re: Don't try this at home...

Carbon Tetrachloride: CCl4. During WW1, wasn't that used to make the gas that was used by the Germans during trench warfare? IIRC, if you heat CCl4, you get it: phosgene gas.

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Old 24th Oct 2018, 8:10 am   #79
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Default Re: Don't try this at home...

A good few years ago I worked for a local medical electronics company (now defunct) and had to visit our agent in Saudi Arabia to train one of their engineers how to service our equipment.
After a successful repair I asked for something to clean the flux residue and was given Carbon Tetrachloride. I protested pointing out how hazardous it was and suggested they use IPA, Isopropyl alcohol. The engineer explained that this was impossible to get in Saudi as alcohol is banned so they had to use Carbon Tetrachloride.

The fact that you cannot drink Isopropyl alcohol did not matter, all alcohol was banned but clearly Health and safety did not matter.............

Peter
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Old 24th Oct 2018, 9:29 am   #80
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Default Re: Don't try this at home...

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Carbon Tetrachloride: CCl4. During WW1, wasn't that used to make the gas that was used by the Germans during trench warfare? IIRC, if you heat CCl4, you get it: phosgene gas.
Yes: I wonder about the low-level exposure to Phosgene that would have arisen when an 'enthusiastic' repairman sloshed CCl4 around while at the same time drawing deeply on the Woodbine or Player's No.6 which seemed to be an obligatory attachment to the lower lip of some techs.
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