Processing

Hides are received into the tannery either as wet-salted on pallets or fresh/iced in tubs from approved suppliers. All fresh/iced hides are processed on receipt, salted are stored and maintained under strict stock control.

The raw salted or fresh hides are processed through what can be a 10 stage production in order to be converted into "wet-blue", the term used for chrome tanned hides.

Inspection

Before inputting the hides are inspected in the hide storage area and prepared into batches for processing.

Soaking/Unhairing

These first two operations are carried out in the same vessel, 7000kg wooden drums are used. The soaking  removes the salt used for preservation  and rehydrates the hides. The hair is  removed using careful additions of sulphide & lime which also allow the hide  to swell under controlled conditions, this opens up the fibre structure and allows better penetration of the chemicals, preparing the hide for further mechanical and chemical  processing.

In both of these operations the processing and batching is computer controlled.

Fleshing

The fat and fleshy matter ais removed  using a fleshing machine, this is done by either a Rizzi or Poletto machine or a Persico throughfeed machine. The removed fleshings are then sent to our rendering plant for oil separation and dewatering.

Splitting (for Limesplit Production only)

If required the hides can be lime split. The splitting operation is carried out using a Poletto machine which separates the grain and flesh layer at the rear, the grain layers are deposited into bins for transfer to the tanning drums, the flesh layer in placed onto a tray for trimming prior to being sent for tanning.

Deliming/Bating/Pickling/Tannage

The first three of these stages are to prepare the hide for tannage.

Initially the delime reduces the pH  and in doing so reduces the swollen nature of the hide, this is done both by washing and chemical additions.

Following the delime bating is carried, this removes the unnecessary interfibrillary proteins by the careful use of enzymes, this gives rise  to a softer more stretchy hide. After bating is completed the temperature of the hides is reduced by washing in cold water this also removes  the dirt from the bating operation.

For the pickling,  salt is added to inhibit swelling which could occur when the pH of the hide is further reduced by addition of acid, this then promotes the penetration of the chrome tanning. For the limesplit hides electrolyte stable fat liquors can be added to give  an improved softness.

The tannage is carried out using Chromium III Sulphate (33% basic). As the process progresses the pH is gradually raised causing the chrome to attach to the hide fibres, by the end of the process the resultant leather good thermal stability properties. 

Samming (if required) and Final Inspection

If required the hides may be passed through a samming machine to remove excess water. Whether or not the hides are sammed they are subjected to a final inspection prior to packing and shipment to our customers.

Throughout all stages of the production from the raw hide to the final tanned hide, the processes are closely monitored; pH, temperatures and Baume reading are tested at regular stages of the process, these along with running times are recorded on the relevant record sheets.