How Your Hide is Being Tanned - Leather in Furniture (Part 3)

In our previous article about leather we examined tanning and how it helps to create long term resistance and strength in the hide as well as maintaining the strength and elastic properties of the hide. We also learned about the different compounds used in tanning such as vegetable tans, synthetic tans, mineral tans and aldehyde tans. In this article we’ll examine how the tanning process is done. How leather hides are inspected and graded and we’ll finish up with how the leather is applied to the furniture frames.

Traditional methods of the tanning process are where the compound being used is applied through a series of vats onto various hides. Water will enter these vats which also contain the compound and is pumped through each vat in progression from vat to vat and so on. When it reaches a vat with fresh material it is extracted by batches of liquor moving down progressively into lower concentrations until it runs out and the vat is filled again with fresh material. More modern techniques developed include paddles which are half circles in a cross pattern. These paddles would produce a constant flex of the hides as they moved around which helped in the penetration of the compound into the hide in a uniform manner. Drums are now the processing medium most used today in modern tanning. Cylindrical shaped drums with a door that can be sealed with pegs lining the inside of the drum. Concentration of tanning compounds can be extremely high resulting in full penetration of the hide within just hours. After the hide is tanned, drying or "crusting out" as the industry refers to it is normal process that happens next and it is during this stage that the hides are sorted out into specific grades based on texture and the quality of the hide itself for subsequent treatment which is part of the reason why you see leather furniture stores offering different grades of leathers at different price points.

Hide skins that have been dried out are taken to a warehouse often referred to in the industry as a "crust" warehouse since the hides are very hard at this point with only simple tanning applied to them. Sorting of the hide skins is an important step for a tannery as the best hides which are premium top-quality aniline leathers will bring the most dollars and leather that must be emobossed (smoothed out and grain stamped back into the hide) to correct flaws will be offered at the least expensive prices often sold at or below cost. When grading the hides many different factors weigh in on how to grade the leather from the amount of insect bites, barbwire marks, stretch marks and so on. The majority of these natural characteristics are present when the hides reach the tanneries and it is at this point that grading will be a little more accurate. Grading of leather though can vary and the skill of the person grading the leather determines what natural imperfections are considered minor or major to the value of the hide.

The next step in the process is called shaving. Leather hides are placed through a machine which will separate the hide and is accurate down to plus or minus .05mm which is an surprisingly accurate. Great care is taken to determine thicknesses for the leather hides being shaved because if too much is shaved off of the hide it would basically be the same as a skiver which would create a very weak skin. When shopping for leather many retailers will talk about leather thickness and this can be an important piece of information to know if it is available as the thicker the cut generally the stronger the hide skin will be in the long term. Once this process is complete the leather hides move onto "clearing" which is the removal of iron deposits that may have occurred during shaving. Once clearing is done the skins are then stripped which is where alkali are added to the leather hides. The reason for this is that it changes the chemical pH of the leather and causes it to go up. When it hits a certain range the tannins will become loose and are removed from the skin. This creates a clean surface that will reduce or eliminate discoloration during the initial tanning or drying stages. When this is completed the leather hide is now ready to have color dyeing or oiling done to the hide.

Now that the leather hides have been colored they are then sent to the furniture manufacturer who purchase these leather hides. Once there they are laid out on a table where a professional cutter will lay out the specific sofa patterns for the different parts of the sofa. They must be as careful as they can to take advantage of every inch of the hide in laying out the cutting patterns due to the cost of the hide. They then cut out each pattern which makes up the different shapes of the sofa like cushions, back panels and arm panels. Once these pieces are cut they are sent on to professionals who sew the panels together by hand using special machinery built for sewing leather. Once this has been done they are sent on to the workers who have the finished frame components built and they will apply foam and padding where needed and will pull the leather over the necessary parts of the sofa and they attach them to the frame. This furniture is packaged and/or boxed and arrives to your local friendly retailer who then offers it for sale to the general public or can special order your choice of color from the manufacturer.

In this three part article we’ve looked at leather and how it starts as a simple raw hide and moves through the process of cleaning and tanning. We’ve examined the process of shaving and how leather is graded based on natural flaws like bug bites, barb wire marks, ect. What makes premium leather different from embossed leather. Clearing was also discussed in terms of how iron deposits are removed from the hides after cutting. Finally we looked at how the furniture manufacturer takes the finished leather hides and applies them to a frame and sends them to your friendly local retailer.

Leather has been processed for centuries in tanneries around the world. The fact that so many tanneries still exist and that so many types of furniture are offered in this covering that are available today is a testament to the quality and longevity that leather can offer. I hope this article was able to explain the long process of what it takes to prepare a raw hide and turn it into furniture use and the reasons why some types of leather cost more than others. The steps tanneries take to ensure preserving and strengthening leather may make the costs of leather furniture higher than many other types of fabric furniture you’ll find but that process was created to make sure that the furniture you buy today will be the same and only furniture you’ll need for years to come.

Phil Pendleton is a furniture professional with over 15 years experience. He has been involved in furniture sales, production and distribution. He continues to work with other furniture professionals to help promote new trends in leather furniture..