We"ve all heard about the "vinegar test" for determining lime or cement, but it's really not just as simple as opening your kitchen cupboards and

taking a small piece of the plaster, render, Mortar or whatever else you are unsure of, putting it in a bowl or on a plate and simply adding vinegar to it.

It's important that people understand what a "cement" is. Conservation Offiers have certainly added unnecessary confusion here with their use of "cemeniticious", but word soup is a fun game, and the "officers" (who never swore an Oath to the Office of the crown to deserve that title of 'Officer' as I did) and mixed up with the armchair experts assuming, but never inquiring, have inferred that can only mean one thing; what is today commonly known as "cement". However, "cement" starts life as limestone, and the additives create the Ordinary Portland Cement's (OPC) faster setting times that is often used as the Adhesive to bind stones together (aggregate) to form concrete for example.

 

Portland is a small island, off the south coast of England, where limestone has been quarried for centuries. 

 

Some of that limestone (or natural chalk in other areas) is used to produce lime powder, in traditional lime mortars, plasters, renders etc, some is also used to produce lime powder in limecrete flooring (NHL's), and more with stones (aggregates) and that binds (adheres) those stones also, because it's an adhesive.

 

The limestone goes throug an intensive process beginning beginning with being heated in rotary kilns, which drives out the Carbon Dioxide (CO²) and moisture from the stone, but lime mixes reabsorb that CO², as part of curing, (carbonisation) from the atmosphere, whereas cement, due to its fast setting 'hardening' doesn't, so which of these two "cementicious" variants are better for today's planetary requirements, and are more sustainable Sir Officer?

 

The simple thinking behind this "test" is  that lime is Alkaline and Vinegar is Acidic so the two will react with one another, and this is seen by 'fizzing' of the Vinegar (the acid) but there is a big, yet little mentioned thing that simply does  not make this as simple as the  arnchair experts like to make out: it may be a thinking, but it's certainly not science.

A bit more

OPC is the common abbreviation used in todays construction industry for Ordinary Portland Cement - Approximately 40% to 60% of 'cement' is actually limestone which has been heated in a kiln to drive out moisture and CO², and then crushed to a powder, and this  is what gives cement the bulk of it's  calcium content.

•  About 20-25% of cement includes clay, silicates, aluminates, and/or iron oxides.
• Some manufacturing plants will also mix in  ground shells, to further increse the calcium content.
• Silicates account for around 5-10% of the overall cement mix, increasing both  it's  strength and durability.

(Hopefully you will have noticed that there's quite a large Elephant already in in the room!) 

 

Limestone is, as the name says, Lime, so how do you know that the vinegar

'fizz' is really because it's pure lime or an older, deteriorated cement?

 

Another issue to be aware of is that cement and lime have been a regular mix since the late 1800's, frequently used in early cavity walls (sorry, but the pre 1900 soild walls / post 1900 cavity wall nonsense is also just not true - been there, seen it too many times, not interested in arguing, to create a pH neutral mix (calcium carbonate,  7 on the pH scale) which wouldn't corrode the early steel cavity wall ties, (there is of course acid erosion, but Alkaline erosion is also very real, so are you looking at a full or half brick wall? I.e are you looking at a mortar mix in a cavity wall, or a 'solid' wall?

 

in these instances which one is your 'magic' kitchen test going to choose?

 

Vinegar contains natural Axetic Acid, in fact it comprises of around 8% Acetic acid. Hydrochloric acid will dissolve lime,  but Hydrochloric acid ostensibly hits  around 40% Acid content  -  vinegar doesn't come anywhere near!

 

But at least today's arnchair experts, no doubt eating their fish & chips with salt and vinegar of course, are entertaining in their ignorance, if nothing else 🤣🤣

 

If you want to know, get it analysed.