Looking for etched metal specimens (or possibly conc. nitric acid)

> Mixing nitric acid and ethanol os an excellent way of making substantial
> explosions - I've twice seen the front of a fume cupboard and once the
> window of a laboratory blown out by accidental mixing of concentrated nitric
> acid with alcohol. In fact in 40 years of working in chemistry labs this
> has been the single most common cause of explosions I have encountered.
>
> Have a look at
>
> http://www.ab.ust.hk/sepo/tips/ls/ls005.htm
>
> But don't even attempt it unless you have a great deal of expertise and a
> safe environment, particularly not with acid and alcohol of unknown purity
> and provenance - it's about as dangerous as home chemistry can get.

> Norman Billingham wrote:
>
> <snip>
>

>> Mixing nitric acid and ethanol os an excellent way of making
>> substantial explosions - I've twice seen the front of a fume cupboard
>> and once the window of a laboratory blown out by accidental mixing of
>> concentrated nitric acid with alcohol. In fact in 40 years of working
>> in chemistry labs this has been the single most common cause of
>> explosions I have encountered.
>>
>> Have a look at
>>
>> http://www.ab.ust.hk/sepo/tips/ls/ls005.htm
>>
>> But don't even attempt it unless you have a great deal of expertise
>> and a safe environment, particularly not with acid and alcohol of
>> unknown purity and provenance - it's about as dangerous as home
>> chemistry can get.

>
> My understanding is as follows:
>
> * That the major hazard is more concentrated mixtures of nitric acid
> in ethanol (the mixtures used for etching are pretty dilute, 1 or 2 %
> concentrated nitric acid in ethanol according to a book I have).
> * That mixtures of nitric acid in ethanol should not be stored.
> * That the acid should be added to the ethanol, not vice versa.
>
> Obviously there are more general safety precautions that should be
> taken, but I'd be surprised if there isn't a safe way of making and
> using this.
>
> Best wishes,
>
> Chris
>

> Christopher Tidy wrote:
>

>> Norman Billingham wrote:
>>
>> <snip>
>>

>>> Mixing nitric acid and ethanol os an excellent way of making
>>> substantial explosions - I've twice seen the front of a fume cupboard
>>> and once the window of a laboratory blown out by accidental mixing of
>>> concentrated nitric acid with alcohol. In fact in 40 years of
>>> working in chemistry labs this has been the single most common cause
>>> of explosions I have encountered.
>>>
>>> Have a look at
>>>
>>> http://www.ab.ust.hk/sepo/tips/ls/ls005.htm
>>>
>>> But don't even attempt it unless you have a great deal of expertise
>>> and a safe environment, particularly not with acid and alcohol of
>>> unknown purity and provenance - it's about as dangerous as home
>>> chemistry can get.

>>
>>
>> My understanding is as follows:
>>
>> * That the major hazard is more concentrated mixtures of nitric acid
>> in ethanol (the mixtures used for etching are pretty dilute, 1 or 2 %
>> concentrated nitric acid in ethanol according to a book I have).
>> * That mixtures of nitric acid in ethanol should not be stored.
>> * That the acid should be added to the ethanol, not vice versa.
>>
>> Obviously there are more general safety precautions that should be
>> taken, but I'd be surprised if there isn't a safe way of making and
>> using this.
>>
>> Best wishes,
>>
>> Chris
>>

>
> Indeed, nitric acid and ethanol can be used as rocket fuel! It might be
> a good time to go over some rules and safe procedures.
>
>
> First, nital etchant should be made freshly for each use, and
> neutralised and discarded immediately afterwards. Never store made-up
> etchant, especially in a closed container. Never reuse etchant.
>
> Some labs make up a batch every day, but you shouldn't do that, it's
> unnecessarily dangerous.
>
> Second, mixing and etching is normally done in a fume cupboard. I can't
> recommend not using one, but it is possible, especially in the
> quantities mentioned below. if adequate ventilation is available.
>
> Wear gloves and eye protection. Keep a source of water handy for washing
> off spills. I add about 2% bicarb of soda to the water, but ymmv. Having
> a second person within earshot, to provide/go for help, is a good idea.
>
>
>
>
>
>
> Please note the importance of setting a procedure and sticking to it,
> following the procedure exactly, every time. Practice the motions before
> doing it for real - seriously, chemists do that, it's surprising what
> you find out. You haven't got enough fingers, and that bottle is just
> out of reach ..
>
>
> One procedure might be as follows: First, prepare the steel sample.
> Wear gloves and eye protection. Measure 10 ml of ethanol into an #empty#
> clean, dry 50 ml polypropylene beaker (eg ebay Item number:
> 120190765576), then slowly add 0.1 to 0.5 ml of nitric acid with stirring.
>
> The amount of acid used depends on the steel, try 0.2 ml to start. Don't
> go above 0.5 ml (5%), it starts getting seriously dangerous then.
>
> Carefully place the prepared sample in the container. It takes a few
> seconds to a few minutes for the sample to etch.
>
> After etching is complete, immediately pour the used etchant over a
> tablespoonful of soaking wet garden lime in a glass or PP container. If
> you only do it occasionally, it is safe to dispose of this down the
> toilet (or in the garden). Do not reuse the etchant.
>
> #Do not refill the beaker until it has been cleaned and dried. Do not
> top it up.#
>
>
> The nitric acid bottle in use should contain no more than 25 ml of
> nitric acid (enough for 50 - 250 etches!). Clean and dry the nitric acid
> bottle when it is empty, then refill it. #Don't part-refill it.#
>
> #Fresh# disposable 1ml polypropylene pipettes (eg ebay Item number:
> 350018678030, but not the 40 x 1 ml offerings, which aren't 1 ml!) can
> be used to measure the nitric acid, but never reuse them - they only
> cost about 6p each.
>
> Never put the pipette into the nitric acid bottle more than once, use a
> new pipette instead.
>
> Put half an inch of garden lime in a tall glass full of water, and rinse
> the used pipettes in it for safety. But do not ever reuse them, it is
> impossible to clean and dry the insides properly.
>
> Clean equipment with 5% washing soda solution. Dry it before use.
>
>
>
>
>
> Ethanol:
> Suitable ethanol isn't easy to get. IMS, industrial methylated spirits,
> and "denatured alcohol" if you can get either of those, are okay if used
> as above. Blue meths is not okay. Vodka won't work properly. Clear fuel
> alcohol, as available in the EU, may be dangerous. Methanol is okay if
> used as above, except the fumes are dangerous.
>
> Isopropyl alcohol has caused explosions, and many people recommend not
> using it at all. If you want to use IPA email me offlist.
>
>
>
> Nitric acid:
> The nitric acid lpchemicals sell
> http://www.lpchemicals.com/product.asp?ProdID=186&CatID=31
> is LR (laboratory reagent) grade and about 70% - this is what is
> normally called "nitric acid" or "conc. nitric acid", and is the right
> stuff to use.
>
> Don't use technical grade, it can be dangerous, use LR or AR grades.
>
> Above 70% nitric acid is usually called white fuming nitric acid. Above
> about 98% it is called red fuming nitric acid. You don't want to go near
> either of those!
>
>
>
>
> All this is perhaps a bit more than required, but if you follow it it is
> about as safe as you need it to be, and it isn't very onerous (except
> perhaps the bit about never reusing pipettes - but that's seriously
> important, don't be tempted).

> Just out of interest, what happens (or might happen) if you reuse the
> pippettes?

> Christopher Tidy wrote:
>

>> Hi folks,
>>
>> I'm looking for a few etched specimens of common metals to photograph
>> under a microscope. Preferably including one or two which show a
>> microstructure which is visually pretty simple. Examples I'd be
>> interested in obtaining include cold rolled low carbon steel,
>> normalised low carbon steel, normalised medium carbon steel, grey and
>> white cast iron, annealed brass, etc. I'm not looking to spend a lot
>> of money. Anyone know where I might obtain some?
>>
>> Another possibility would be to obtain some concentrated nitric acid
>> in order to make the nitric acid and ethanol mix required for etching
>> most ferrous metals myself, but concentrated nitric acid doesn't seem
>> easy to obtain.
>>
>> Any suggestions? Thoughts would be appreciated.

>
>
>
> You can buy nitric acid from lpchemicals, but they have a minimum £50
> order (plus carriage and VAT).

> If you are anywhere near Trowbridge, Wiltshire, I can let you have some.
> But I can't post it :(