Tanneries Haas are specialized in calf tanning. The skins that come out of their workshops are of exceptional quality, known by the greatest luxury houses.

At Phi 1.618 we had the chance to discover this high place of tanning where more than 90% of our leathers come from. Sébastien Croidieu guided us through the different stages to obtain this magnificent leather: river work, tanning, wrought iron and finishing or embellishment.

Beyond the know-how, it is also the level of transparency of the information that we appreciated: the origin of the skins, the tanning products, the respect for the environment. We are proud to work with such an extraordinary French supplier, which has existed since 1842. We detail everything below!

The skins come from local French producers. They come from the meat industry and by transforming them into leather, tanners optimize the use of the animal.

  • The River Workshop

To be well preserved, the skins arrive salted at the tannery. The water will remove this salt. The water (which is no longer that of the river) is constantly reprocessed to avoid any pollution.


Then the skins are passed through a sewing machine to remove the hairs and their thickness is mechanically equalized.
They are then visually checked and stored according to their quality and size. They are  dried so that the next tanning step takes place correctly.

  • The Tanning Workshop

This operation is carried out in a fuller, a sort of huge washing machine, by successive additions of tanning agents such as chromium salts or plant extracts.
Chrome plating is a part of the leather tanning process which can have a negative connotation as opposed to mineral tanning.

At the Haas Tanneries, the use of chromium III (and never chromium IV, which is very toxic) is also highly regulated and goes through a precise mixing process to obtain the best result, but also through a long step of removing the chrome after chrome plating.
European REACH standards are very strict, but chromium IV is still used in tanneries outside Europe.
At Phi, 90% of our leathers use the mineral tanning process. Check out the different tannings here in our previous blog post .

  • The Wet-Blue Sorting

Chrome III has a magnificent emerald color and the skins take on a pale blue color after chrome plating which explains their name of "wet blue".
The skins will now be checked and selected with more precise criteria: size, thickness, aspect, surface.
They are then adjusted to the thickness according to the customer's request during slitting and disengagement operations.


  • Retanning and Tint steps

These operations again take place in drums (stainless steel, wood or polypropylene) of different dimensions.
This is a second tanning applied to wet-blue hides. The upkeep-retanning operation will give the mechanical characteristics specific to each article.


It is followed by the tint operation which gives the skins their basic coloring.
This is the most inspiring part for us! Different color mixtures are made to obtain the desired shade. This is applied using a special machine which guarantees a uniform layer of color.

  • Wrought iron, a term that covers several stages

The next steps consist of the airing, vacuum drying, softening and pressing. Many technical terms to arrive at the selection and printing of the grain of leather on dried hides. Not all of the patterns you see on skins are natural!



  • Finishing is the last stage of production

The skins must be made homogeneous by giving them the characteristics of appearance (more or less satin), touch (flexible or held, more or less polished) and resistance requested by customers.


There are a lot of different grains. At Phi 1.618, we use grains such as Epsom, cork or caviar for our bags. For the belts, it is the smooth leather that we choose.

  • Quality control is carried out in the laboratory

Once the skins have been fully processed, they should be tested for quality and it is necessary to ensure that they retain all of their color properties. Haas tanneries have their own laboratory for abrasion, flexion and resistance tests, but use external laboratories for chemical tests.


Luxury houses tan more hides than necessary for their leather goods production to ensure exceptional quality. The skins not retained constitute the "dormant" stocks. It is from these stocks that our designer Juliette Angeletti selects each skin one by one. This is how the leather of our creations is tanned and then chosen.

To discover the steps and process of making a bag with this leather in our workshop, click here !

June 10, 2021