Pancakes anyone?

One area for concern is chimeys, especially when replastering cimney breasts and returns with lime plaster.

Why?

Of course we have modern day developments readily available, such as wall mounted boilers fuelled by gas  to create heat in our homes. Basically water is heated in a chamber concealed inside the boiler and then this heated water is pumped through pipework to the radiators fitted in each room around the house.

But  that's really quite a new development in domestic homes, In fact a 1970's development, and before that the main sources of heating were open fires which were used to burn logs, coal, and sometimes anthracite to heat domestic homes. Many were also used for cooking over, and also for baking breads in.

Chimneys would transport the smoke from the fires up to their exit points: the chimney pots.

As can be seen below, chimneys are actually carefully designed and engineered to ensure good heat is given out to the rooms while the smoke is removed out of the home as fast as possible. 

Over the period of centuries and/or decades where that chimney carried a lot of smoke, it also carried a lot of Sulphates, Nitrates and creosotes created by the materials being burned in the fire, and these will have lined the internal chimney flues and in time will have soaked into the chimney brickwork. Then comes the day when a brand new coat of lime plaster is applied,  but only to not take long before horrible looking stains appear on the face of the chimney breasts. 

So how do cow pancakes work?

First of all: Don't eat them!

The application of cow manure and lime can help prevent soot staining because of a combination of factors:

• Physical Barrier: The organic matter in the manure, including hair and fibres, can create a physical barrier that helps to prevent soot particles from penetrating pores (capillaries) of the lime plaster.

• Chemical Reaction: The alkaline nature of lime reacts with the acidic components in soot, which in turn neutralises them and reduces their staining potential. The cow manure also contains humic acid and tannins both of which are chemical compounds known as chelating agents. Some organic components in cow mamure also have adsorbant properties for certain types of stains. Complex organic polymers and humic substances can have various functional groups that can bind to soot components through van der Waals forces, hydrophobic interactions, and other mechanisms, further trapping them within the cow muck coating. 

• Sealing Properties: The oils and fats in manure can help to seal the pores of the plaster, further reducing the penetration of soot particles. This reduces the pore size so that oils and tars created by the chimney exhaust fumes cannot pass through. 

For the best results fresh the cow manure should always be used, as it contains the most effective components. Ideally the manure should be well-mixed into the lime plaster to ensure even distribution. Alternatively, fresh cow manure thinned with cold water can be brushed onto the chimney breasts and returns, effectively becoming  a stain blocking 'paint' and allowed to fully dry before lime plaster is applied, this method is also a little easier to spend time around afterwards as when it's nixed into the lime plaster you are dependant on time before the evaporation an carbonisation 

Processes have completed, so it's a good idea to decide whether you can leave the house empty and go elsewhere to eat and sleep until the plaster has fully set, or not!

The early morning 7am stops at the local dairy farm was one of our jobs as starters in lime mixing, because when cows are lined up and being milked, their stomachs tend to get a bit 'excited' and their lined up formation made catching fresh, warm pancakes much easier than running around the field chasing cows who were only interested in eating grass