Wiki: Alkali

[NT]

Feedback welcome

NT

==Caustic soda==

*Strong alkali *Cleans ovens *Unblocks drains *Strips [[paint]] *Toxic, irritant, can cause serious eye injury. *A relatively high risk chemical, follow instructions with care.

*It is important to add crystals to [[water]] gradually, never the other way round.

*Use rubber gloves, plastic apron, [[goggles]].

*Products containing thickener (eg Ronstrip) are less likely to run off the workpiece, and more effective at [[cleaning]] or stripping on non-horizontal surfaces.

*Paint stripping paste may be made with hydrated lime and caustic soda

*Paint stripping paste may be made with caustic soda & wallpaper paste, (excess caustic can destroy the paste)

==Sodium silicate== dishwasher cleaner

==Washing soda==

*Degreases when used with hot water. *Mostly used for clothes degreasing *Unblocks drains. The majority of drain blockages are mostly solidified fat. Half a cup of soda in hot water works well, but use eye protection as it can spit alkali when mixing *Discolours aluminium, and can dissolve it in some cases.

*For greasy washing, a teaspoonful in the machine is plenty, with a hot wash.

==Sodium bicarbonate== aka baking soda or bicarb

*a mild safe alkali with many uses

*For brushing teeth, use wetted bicarb like toothpaste. Its abrasive to plaque but not to teeth, and is a stain remover, but lacks fluoride

*Removes tea and coffee stains

*Cleans ovens

*Reduces laundry odour: add to final rinse

*Removes black scuff marks from floors

*Cleans plastic / fibreglass baths

*Freshens sour dishcloths: soak in water and bicarb

*Deodorises laundry awaiting washing: sprinkle in the basket.

*Removes crayon marks: use a brush and soda paste.

==Lime==

• Makes an array of [[paint]]s

• Used in lime [[mortar]]

• Used as plasticiser in [[cement]] mortar

• Used for lime [[plaster]]

• Occasionally cause extreme burns down to the bone, but usually doesn't burn at all. Be wary of skin contact

• Used to crisp pickles, and formerly used for preserving eggs

Lime exists in several forms:

• builder's lime: hydrated non-hydraulic lime, good for [[mortar]] etc

• hydraulic lime: sets faster & harder, for more specialist uses

• Quicklime: non-hydrated, vicious on skin, and can sometimes burst into flame when soaked with water

• Lime putty: made by mixing water with quicklime or builder's lime

==Safety== Some alkalis can cause serious eye injury. The damage takes time to occur, so may not prompt a person to seek medical assistance. Major damage can occur. Use eye protection.

Don't mix alkalis with [[acid]]s, rapid reactions may occur, spitting acid or alkali. It can also melt through whatever its in. The same can happen when adding hot water to strong alkali

Strong alkalis should also be kept off skin.

[Martin Brown]

Apart from the fact that you have missed out one of the most vicious of them all sodium methoxide (which is relevant these days with the advent of DIY biofuel manufacture) and that stuff is completely unforgiving.

It pretty much combines all the worst properties of methanol and caustic soda. I don't see why you are doing this though as Wiki already has perfectly good entries for alkali and for all these common reagents.

Solid is very corrosive to skin and unforgiving of minor mistakes. Dissolving it in water can be highly exothermic - enough to boil.

Potassium hydroxide is also encountered in NiFe and NiCad batteries. Hydroxides rapidly absorb CO2 from the air to form carbonates.

Aka waterglass - once used for preserving eggs. Still not good for you but a lot less dangerous than NaOH.

All the other strong alkalis will destroy aluminium in no time flat.

I think biological powders probably work a lot better than this old soldier. They also require fairly agressive high pH to work.

With the application of infinite amounts of elbow grease.

Prolonged skin contact with any strong base will get you into trouble, but I think the only one that will go down to the bone is quicklime. That stuff is beyond imagining in terms of how it behaves on contact with water (and humans are mostly water).

What ??

Quicklime in a pit is also used for disposing of diseased carcasses with enough heat to sterilise them during eg foot and mouth or plague.

It's not something you want on your skin but it is a lot safer once it has been slaked. Quicklime is really dangerous for beginners.

All of them are really serious in the eyes so wear eye protection.

Any skin contamination should be washed off with copious amounts of water and quickly. It is toughing it out until a burn becomes obvious that leads to serious levels of damage. All of them feel soapy to touch because they are turning the fats in your skin literally into soap!

I am assuming here that the intention is to provide useful advice to people who handle these things in a DIY context.

[Davey]

for 'eggs'.

[The Medway Handyman]

Explain the pH scale?

Exothermic reaction?

Most paint strippers are based on Methylene Chloride not Caustic Soda

You should never, ever, ever, ever, ever try to make up your own blends. Marketed products are formulated by highly skilled, qualified, experienced chemists.

Almost useless.

Almost anything does, inc WD40 - but they treat only the symptom.

[The Natural Philosopher]

which is sometomes a very useful thing to have.

Violently boiling water creates a useful drain cleaning pressure.

Wrong order. Skin will survive alkali burns - eyes wont.

Yes. Even caustic won't get pure carbon off.

[Martin Brown]

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[large snip]

Idiot. Learn to read! He has it listed under lime and quick lime. Waterglass is sodium silicate not lime.

[Davey]

You put it under Sodium silicate, and that was what I was repliyng to.

[stuart noble]

Eh? Caustic based strippers are very straightforward because the alkali destroys any thickeners you might add to it. Only starch can survive (flour will do) but that produces a virtually unusable gloop.

I guess ammonia should get a mention?

[Tim Watts]

You can use lime as a thickener - makes a paste.

[docholliday93]

You mean, most paint strippers *were* based on Methylene Chloride until it was banned for that application...

[stuart noble]

Haven't tried that but, like all mineral thickeners, you come up against the weight problem i.e. on vertical surfaces it slumps as soon as it starts to work. Same thing happens to a lesser extent with gels.

Using toilet tissue as a thickener works quite well with the advantage that it soaks the gunk up and, in ideal conditions, dries to a peelable skin. Still sags though.

Just paint everything white a la sixties :-)

[Tim Watts]

I did, a long time ago. It would hold 1/2" thick on the vertical if you got the mix right, but it was not quite "Ronstrip" - I think they added a plasticiser too. It tends to harden in due to evaporation which counteracts the slumping as the paint dissolves.

But it was a messy faff and like any water/caustic stripper it did raise the grain. OTOH it was the only way to remove 1940-1950's "toffee" varnish.

That's a good one - I like that!

Or have bare wood lightly oiled or coated with a microporous stain/finish - not much buildup over recoats :)

[NT]

Do sodium methoxide and Potassium hydroxide have any diy uses?

I checked the wiki, and am pretty certain there's no article covering these. Wikipedia has an alkali article, but its not of much relevance to diy, so little point linking to it.

NT

[NT]

Version 2...

NT

Alkalis are high pH and generally highly corrosive substances used for cleaning, paint stripping, mortar, plaster, drain clearing and other diy tasks. They have sizeable risks and require handling with due care.

=3D=3DCaustic soda=3D=3D

*Strong alkali *[[Clean]]s ovens **Foaming products help it cling *Unblocks drains *Strips [[paint]] *Toxic, irritant, can cause serious eye injury. *A relatively high risk chemical, follow instructions with care.

*Causes the majority of household chemical burns

*It is important to add crystals to [[water]] gradually, never the other way round, dissolution is strongly exothermic.

*Use [[goggles]], rubber gloves, plastic apron.

=3D=3D=3DPaint stripping=3D=3D=3D Caustic soda strips oil based (alkyd) paints.

*Products containing thickener are less likely to run off the workpiece, and more effective at [[cleaning]] or stripping on non- horizontal surfaces. *Paint stripping paste may be made with caustic soda mixed with any of **builder's lime **wallpaper paste (excess caustic destroys the paste)

**toilet paper

**boiled flour (excess caustic destroys the paste)

Covering the paste with clingfilm keeps it working much longer

=3D=3DSodium silicate=3D=3D

*aka waterglass *dishwasher cleaner

*once used to preserve eggs

=3D=3DWashing soda=3D=3D

*Degreases when used with hot water. *Used for clothes degreasing & removal of some stains *Unblocks drains. The majority of drain blockages are mostly solidified fat. Half a cup of soda in hot water works well, but use eye protection as it can spit alkali when mixing *For greasy washing, a teaspoonful in the machine is plenty, with a hot wash.

=3D=3DLime=3D=3D

• Makes an array of [[paint]]s

• Used in lime [[mortar]]

• Used as plasticiser in [[cement]] mortar

• Used for lime [[plaster]]

• Used to crisp pickles, and formerly used for preserving eggs

Lime exists in several forms:

• builder's lime: hydrated non-hydraulic lime, good for [[mortar]] etc

• hydraulic lime: sets faster & harder, for more specialist uses

• Quicklime: non-hydrated, vicious on skin, and can sometimes burst into flame when soaked with water

• Lime putty: made by mixing water with quicklime or builder's lime

Lime is sometimes sold as a [[desiccant]] to dry [[damp]] cupboards etc. Its not really effective. It does work in drying an airtight sealed container, but not a room.

*Quicklime is highly reactive and does serious damage on contact with any part of the body. It spits when slaked. *Builder's lime usually doesn't burn at all, but occasionally causes severe burns right down to the bone. Be wary of skin contact.

Quicklime is also used to dispose of diseased animal carcasses.

=3D=3DAmmonia=3D=3D

• Choking fumes

• Avoid contact with eyes, skin and nose/lungs

• Use it outdoors whenever possible.

• If used indoors, ensure plenty of ventilatiobn, and use a wet breathing filter. Many filters work acceptably when wet

• Can be used as a cleaner, preferably only in cases where nothing else has worked.

=3D=3DSodium bicarbonate=3D=3D aka baking soda or bicarb

• Technically this is a base rather than an alkali, and is mild & safe with many uses

*For brushing teeth, use wetted bicarb like toothpaste. Its abrasive to plaque but not to teeth, and is a stain remover, but lacks fluoride

*Removes tea and coffee stains

*Reduces laundry odour: add to final rinse

*Removes black scuff marks from floors

*Cleans plastic / fibreglass baths

*Freshens sour dishcloths: soak in water and bicarb

*Deodorises laundry awaiting washing: sprinkle in the basket.

*Removes crayon marks: use a brush and soda paste.

*Is sometimes touted as a multipurpose cleaner, but better products exist *Used in cakes & soda bread

=3D=3DSafety=3D=3D Alkalis can cause serious eye injury. The damage takes time to occur and isn't felt, so may not prompt a person to seek medical assistance. Major damage can occur, upto blindness. Always use effective eye protection.

Adding most alkalis to water generates heat, and boiling mixes can spit. Don't do it unless you're well protected against splashes.

Don't mix alkalis with [[acid]]s, rapid boiling or violent reactions may occur, spitting hot acid or alkali. Some mixes can go well above

100C and melt through whatever its in, or shatter [[glass]]. The same can happen when adding hot water to strong alkali.

Strong alkalis should be kept off skin. Caustic soda and quicklime are particularly nasty, but others have been known to cause severe injury at times. If any skin contact occurs, the alkali should be washed off with copious amounts of [[water]].

Due to these risks, the use of strong alkalis for [[paint]] stripping is objected to by some diyers, while its practised by some. The risks and long soaking time require prevention of any nonessential access to both humans and animals.

Alkalis in general can discolour or completely dissolve aluminium.

=3D=3DSee also=3D=3D

*[[Paint]] *[[Cleaning]] *[[Laundry]]

[[Category:Basics]] [[Category:Chemicals]] [[Category:Cleaning]] [[Category:Laundry]] [[Category:Materials]] [[Category:Safety]]

[Martin Brown]

It depends whether or not you count making your own bio-diesel as DIY. Most practitioners seem to think they are just dissolving KOH or NaOH into the methanol but the reality is a bit more scary. Intro level at:

people selling the kit for doing the reaction tend to emphasise how simple it is. I am surprised there have not been more accidents... full face shield is strongly recommended.

And potassium hydroxide is what leaks out of abused alkaline cells although it fairly rapidly becomes carbonate on exposure to air.