Working with Atmospheric Pressures – #TanneryInsights

There are several machines used daily in the tannery that quicken up the drying process. You will have heard of the phrase ‘more hands make light work’ well this is most definitely the case when it comes to laying out hides on each plate of the vacuum dryer.

The purpose of this stage in production is to reduce the moisture content percentage from the fibres within the leather. By working below atmospheric pressure, we can achieve the quick reduction of moisture content. This technique is just one of the ways we can dry out leather, other ways include hang drying which can be left for several days or conveyor chamber drying.

Jamie and Callum who are featured in our Instagram post have a combined 28 years working on this machine as well as others in the tannery. They work as a team of four to effectively lay out the hides to use the maximum surface area of the heated surface.

Technical know-how: In atmospheric conditions, water will boil into steam at around 100⁰C. By creating a vacuum layer around the wet hides, we can reduce the volume of air in the machine quite quickly. The water will boil at a lower temperature when the air pressure is lower than typical atmospheric pressure, thus removing excess water molecules from the leather fibres faster.

The temperature of the plates used when the vacuum seal is activated will vary between 30⁰C and 50⁰C depending on the thickness and wetness (moisture content) of the leather before it arrives for the next stage in production. A compression of air is noticeable on our video posted today on Facebook.