I have now declared war on my Sandtex

[robgil]

that sounds like a great idea , is caustic soda dangerous then?

 

[Flyfisher]

Dangerous? Well, yes and no, like most things. Take the appropriate precautions and there should be no problems. A bit like bleach really - don't get it on your skin, don't get it in your eyes and don't drink it.

I remember bottles of it (Sodium Hydroxide) in the school chemistry lab, but I guess they don't allow that anymore. :roll:

 

[Penners]

is caustic soda dangerous then?

The clue is in the word, "caustic". It's a powerful alkali and can burn your skin. Even more importantly, don't get it in your eyes, as FF said.

Many years ago (before the arrival of modern paint strippers such as Klingstrip), I stripped some old doors in a bath of caustic soda. The technique was to float the door on the liquid then stand on it, to sink it. The critical point was to wear wellies.

Unfortunately... I didn't know that one of my wellies had a small hole in it. Only a tiny amount of the liquid got inside, but my toenails and all the hair on my toes went black. :x

 

[Penners]

I remember bottles of it (Sodium Hydroxide) in the school chemistry lab

Do I remember correctly that NaOH is one of the few things that will corrode glass - albeit quite slowly?

 

[Flyfisher]

I only knew of hydrofluoric acid dissolving glass, but your memory seems as infallible as ever. Wikipedia states "Sodium hydroxide is also mildly corrosive to glass, which can cause damage to glazing or freezing of ground glass joints.", which might explain my recollection of various bits of seized glassware in chemistry labs.

It also seems to be quite handy for leaded glass window restoration, dissolving bodies and "Olives are often soaked in sodium hydroxide to soften them". :shock:

http://en.wikipedia.org/wiki/Sodium_hydroxide

 

[Jill]

I use both NaOH and Hf at work and wouldn't recommend anybody using them without they knew what they were doing. Sodium Hydroxide in solution if you get even the slightest bit on your fingers gives a soapy feel. A young colleague was itching his ankle one day, it was discovered he had got a single sodium hydroxide pellet tucked in his sock. How that happened I will never know. If we are using Hf we have to be accompanied by somebody else as we are not allowed to use it on our own - even though for many years we did - if we get that on ourselves we have to by pass the medical centre and get taken straight to hospital.

 

[Flyfisher]

I'm not surprised about the HF precautions; I'd say it's far more dangerous than caustic soda:

http://en.wikipedia.org/wiki/Hydrofluoric_acid[/url]"]
Hydrofluoric acid is a highly corrosive liquid and is a contact poison. It should be handled with extreme care, beyond that accorded to other mineral acids. . . . HF penetrates tissue more quickly than typical acids. Because of the ability of hydrofluoric acid to penetrate tissue, poisoning can occur readily through exposure of skin or eyes, or when inhaled or swallowed. Symptoms of exposure to hydrofluoric acid may not be immediately evident. HF interferes with nerve function, meaning that burns may not initially be painful. Accidental exposures can go unnoticed, delaying treatment and increasing the extent and seriousness of the injury . . . . . . HF chemical burns can be treated with a water wash and 2.5% calcium gluconate gel or special rinsing solutions. However, because it is absorbed, medical treatment is necessary; rinsing off is not enough. In some cases, amputation may be required.

Definitely not the stuff for 'kitchen chemistry'. :shock:

 

[Penners]

And probably not ideal for softening olives.

 

[Matt Green]

Hf is insane stuff:

A woman etching computer chips developed a pin-hole in her
glove during the four hours that she was working in a dip tank
with 5% hydrogen fluoride. She went to a doctor's office where
a non-specific burn ointment was applied (no calcium was
applied). She continued to have pain during the next four
days. At that time she had severe pain under the finger nail
and the subungual tissues were black. There was mild erythema
around the proximal cuticle. Upon removal of the finger nail
at a burn treatment center where she was referred, exposed and
necrotic bone was identified. The distal phalanx was
demineralized and the patient required distal amputation of the
finger (Edelman, 1986).


I turned the end of one of a newish pair of shoes into soap with NaOH in an A level chemistry class. My father nearly throttled me and I had to buy my own shoes after that. It's one of the few things I can still remember about that course. Dullest qualification ever- no wonder it's under subscribed.

M.

 

[Nigel Watts]

Half my porch is now covered in a Kligstrip and polythene poultice and the house is starting to look like Christo has been at it. I am going to leave to poultice on for a few days before seeing how well it has worked.

Worked on it for a couple of hours yesterday and the same again today. Manual labour is so exhausting, but then I have just spent the last 30 years couped up in offices. Cups of tea after the labours have been completed have never tasted so good though, even without the three sugars builders seem to like.

 

[Flyfisher]

Worked on it for a couple of hours yesterday and the same again today. Manual labour is so exhausting,

Yep, it's a tough life alright, but stick with it and before long you'll be able to last a whole half-day. :wink: :lol:

You're dead right about a good cup of tea though!

 

[Lime]

Hf is insane stuff:

A woman etching computer chips developed a pin-hole in her
glove during the four hours that she was working in a dip tank
with 5% hydrogen fluoride. She went to a doctor's office where
a non-specific burn ointment was applied (no calcium was
applied). She continued to have pain during the next four
days. At that time she had severe pain under the finger nail
and the subungual tissues were black. There was mild erythema
around the proximal cuticle. Upon removal of the finger nail
at a burn treatment center where she was referred, exposed and
necrotic bone was identified. The distal phalanx was
demineralized and the patient required distal amputation of the
finger (Edelman, 1986).


I turned the end of one of a newish pair of shoes into soap with NaOH in an A level chemistry class. My father nearly throttled me and I had to buy my own shoes after that. It's one of the few things I can still remember about that course. Dullest qualification ever- no wonder it's under subscribed.

M.

The lab where I worked in the 60s used both sodium hydroxide and 5% hydrofluoric acid in large quantities to clean glass CRT tubes prior to laying down/settling the screens.

The liquids were squirted under pressure vertically upwards into the air and into the glass tube you were washing.
There were no safety features fitted whatsoever so it was quite possible to squirt the acid or caustic onto the ceiling if you weren't careful.

The problem with hydrofluoric acid (hydrogen fluoride in water) is that the effects on animal tissue is not altered by how dilute the acid is.
Nearly all other acids have an effect on flesh but the concentration normally dictates the amount of damage.
With hydrofluoric acid that isn't the case.
A 1% acid solution is as dangerous as a 10% solution.

the method of safety was as follows:

Horror pictures on the wall showing bone damage etc.

An initial verbal warning not to turn the spray tap on before putting the glass over the spray.

My attention was drawn to the large sink in the corner of the room into which a tap was left running day and night.
I was to wash off any acid or alkali for a few minutes.

Go to Sister's on the otherside of the building (it was a big building) if I felt I should.

That was it.

I'm still alive.

 

[Nigel Watts]

First application of Klingstrip has now been peeled off in the test area of my porch after leaving it for four days. Good news and bad.

Bad news is that it's only got about half way down through the paint layers and will need a second application.

Good news is that it has shed an interesting light on one of the possibly many different exterior paint schemes. In the first picture the left of the porch was stripped with Klingstrip; on the right it was much looser and could be scraped.

Porphery-like paint effect, about half way down the layers

Evidence of a dado in the porch and later green and cream scheme

Original stucco layer in the black/brown area top centre left. The original scoring to imitate the ashlar joints can clearly be seen.

Ceiling of porch and its cornice (much loose plaster here unfortunately) painted in the same ochres and browns as walls. No evidence as yet of anything polychromatic, unlike on the inside.

 

[Nigel Watts]

Working in my area on the paint stripping this afternoon I overheard two men outside my attached neighbour's house, recently repainted in cream and brilliant white Dulux.

Man 1 : "I nearly bought this house once for [sum indicating that this must have been at least a decade ago]"
Man 2: "Beautiful house"

The pair begin to stroll past my house, its mirror image.

Man 1, in a knowledgable tone : "This one, of course, would be much cheaper."

I chuckled. I rather like the idea of spending time and money on restoring and decorating my house sympathetically and thereby making it less valuable.

 

[jocelyn plummer]

What an ignoramus the passer by is.

 

[Gareth Hughes]

Ah, but Nigel is cunningly repairing it so that, from the front, and to some extent inside, it will look as though it hasn't had any work done since 1875 (except for suspiciously fresh paint, which the punter in the street won't notice) and is therefore "ripe for restoration"