Soft, Fluffy, and Butter Touch Leather from Wetblues Part IIn order to produce such article, the most important basic thing that one has to consider is to restore our wetblues as close as possible to its original condition.Why?
Good wet blues depends on a lot of factors such as:
What if we start from wetblues? Today, due to high costs of effluent treatments, tanners prefer to purchase their wet blues from various sources. Since none of the water used in the beamhouse up to tanning are similar, some are from very soft water area and some are from very hard water area, it is very difficult to have good uniform wet blues, especially when one buys from different sources. How do we go about solving this issue? Like in western cow boy movies, shoot first and talk later. What we should do is to assume that all the wet blues are from arid countries, where water is scare and often is very hard. Hard water?What happen if your wetblues are tanned with hard water?
You will end up having calcium deposits on the grain, the harder the water the more calcium deposit you will have. Calcium in the form of calcium carbonate depositing on grain is like adding layer of stone powders to the grain! How can we remove calcium deposits? The first thing to do is to just soften wet blues by soaking in water for a few hours to loosen the grain fiber structure, otherwise proceed without proper softening of grain can end up with grain damage and damage fiber and fibril structures. After wet blue had soften down sufficiently, the add Alchem 1061 ( which is acidic wetting agent ), Alchem DW ( which is calcium and other chemical deposits remover ) and Alchem CA2 ( which is undesirable minerals remover ). At what dosage? Rule of thumb is to start with 2% each of Alchem 1061 and Alchem DW and 0.2% Alchem CA2 with 50% water. These dosages are based on shave weight calculation and by far this is standard procedure one can take. More chemicals will be needed if wet blues are exceptionally poor. |
Float and TimeWhy do we need short float during the beginning of wetting back?
Initially, we need good mechanical action on the wet blues for better penetration and reaction of Alchem 1061, Alchem DW, and Alchem CA2 with all the undesirable chemicals chemical components like chrome deposits, calcium carbonates, natural lipid soaps ( reaction of natural fats, oils, or greases with calcium and other minerals ), …, etc. How much time do we need for proper wetting back operation? In general for dried out wet blues, it will require about 1.5 days with 3 to 4 hours of intensive drumming action before leaving over night with intermittent running of 20 minutes every 2 hours stop. On the next day, we will find that the wet blues are soft enough but still not plump with floats of dirty greenish color. Then add 150 to 200% water and run at least 90 minutes. This time one should discover that the wet blues had plumped up properly with smooth grain. Acid Bate and Oxalic Acid in Wetting Back?Should we use acid bate and oxalic acid to assist wetting back?
We strongly recommend to avoid because enzymes in the acid bate will starting to digest grain, collagen, and other hide protein and will results in pipery and loose leather with very poor empty breaks. Over use of acid bates might end up with nubuck effect grains with poor tensile strength. While oxalic acid will detan leather and leave leather feeling empty and hard. How does one determine whether wetblues had been properly wetted? Feel the grain. When wet blue is properly wetted, it should leave smooth spongy round feel like fresh wet blues after tanning with light bluish color. What are the signs of insufficient wetting back?
What should one do? Some times when the wet blues are too dried out and we had not adjusted shave weight properly, we might end up with under weight wet blues which will lead to insufficient chemical dosage. Rule of thumb, is to drain out all the under wetted wet blues and weigh. Then multiply by 0.6 in order to get the closes shave weight and the start all over again using this new weight. |
Soft, Fluffy, and Butter Touch Leather from Wetblues Part II
Often time tanners had been focusing costs saving by procuring only cheapest chemicals, without regards to operation details, that if carried out properly can help to reduce production costs substantially by improving better chemical fixation to leather and consequently reducing chemical dosage. With better fixation of chemicals to leather means better quality leather, means less quantities of chemicals are required, less unfixed chemicals in the effluence, means less costs for waste water treatments.
After we had totally returned our wet blues into their original state, the next following steps will be washing, retanning, dyeing, neutralizing, and fatliquoring.
From Part I we had sufficiently removed all the undesirable chemicals, which includes, chrome soaps, calcium carbonates, loose grease or fats in the wet blues, …, etc, washing is very essential.
After we had totally returned our wet blues into their original state, the next following steps will be washing, retanning, dyeing, neutralizing, and fatliquoring.
From Part I we had sufficiently removed all the undesirable chemicals, which includes, chrome soaps, calcium carbonates, loose grease or fats in the wet blues, …, etc, washing is very essential.
What are the factors of washing that we have to consider?
How can we wash as thoroughly as possible with minimum water, because extra water will end up in effluent treatment plants and will incur additional unnecessary costs?
We found from our experiences that the best washing is to mimic our washing operation to washing machines, with the following procedures:
- Should we using rinsing or washing? Rinsing means to wash with running water, which means using huge quantities of water is required. Washing means to wash with limited water quantities, which means less water is required.
- Time. Best washing is to clean wet blues from undesirable chemicals with minimum water and minimum running time.
We found from our experiences that the best washing is to mimic our washing operation to washing machines, with the following procedures:
- First drain as thoroughly as possible, the dirty wetting back water.
- Add only 50% of new water and run for 20 minutes. This very short float should improve our cleaning with minimum water by utilizing gravity to help squeeze out dirty water from the hide cross section.
- Then add another 50% water to the drum in order to dilute as much as possible all the undesirable chemical that were present in the float. Run for another 10 minutes and then drain. Please observe the water condition before draining.
- Repeat the same procedure again for the second time and observe the water condition, when compare to the first wash. If the water is clean, then proceed with next step of pre-dyeing, retanning, and pre-fatliquoring. If the water is still very dirty repeat another washing. ( It is very important to clean wet blues from undesirable chemicals as thoroughly as possible because these undesirable chemicals can cause a lot unwanted properties to our leather by hampering proper uptake and penetration of subsequent chemicals. )
Why do we need to do pre-dyeing in the rechroming bath?
For producing jet black leather it is very necessary to do pre-dyeing with good acid dyes at this state because the dyestuff that we applied here will be very firmly fixed to leather due to subsequent retanning operation in the same float. Addition of 1% or more of very good jet black acid or metal complex dyestuff at this state will great enhance the surface jet blackness to final leather, run for 10 minutes should be more than enough to exhaust them. We should start with short floats like 50 to 75% in order to maximize chemical uptake into leather.
Then follow with our retanning agents, Altan MC or Altan MR, d should be chosen for very soft and fluffy leather. Altan MR should be chosen for soft, round, tight, but less fluffy leather. The dosage should be around 4% by breaking into two portions, half goes with dyestuffs and the other half goes with 6% chrome ( 33 basicity ) and fatliquor with 1% Phosphonol LHE ( full synthetic electrolyte stable fatliquor ) and 1% Eurekanaol 2012 ( full natural electrolyte stable fatliquor ), with 0.2% MgO as basicfying agent, all added in the same float and run for at least 90 minutes. Then follow by addition of 150% water @ 50C. Run for another 60 minutes. ( The float here should be almost clear. )
Then follow with our retanning agents, Altan MC or Altan MR, d should be chosen for very soft and fluffy leather. Altan MR should be chosen for soft, round, tight, but less fluffy leather. The dosage should be around 4% by breaking into two portions, half goes with dyestuffs and the other half goes with 6% chrome ( 33 basicity ) and fatliquor with 1% Phosphonol LHE ( full synthetic electrolyte stable fatliquor ) and 1% Eurekanaol 2012 ( full natural electrolyte stable fatliquor ), with 0.2% MgO as basicfying agent, all added in the same float and run for at least 90 minutes. Then follow by addition of 150% water @ 50C. Run for another 60 minutes. ( The float here should be almost clear. )
Why do we need 150%, 50C hot water?For very good fixation of all the chemicals, especially chrome.
Why is washing here very important?
Here again thorough washing is very important because subsequent chemical uptake can be impaired due to the loose unfixed chrome in the leather. Good washing can be done with repeating the washing procedures above.
Why do we need to start neutralization with good dispersing syntans and Altan MR?
Good dispersing syntans like Tamol M or similar product, when used together with Altan MR, will help to keep grain smooth, soft and full. It is advisable to break dosage into two portions of equal parts and run for at least 20 minutes, with the second part add with ammonium bicarbonate.
Why do we add fatliquors to neutralizing bath?
We found that fatliquoring at this state is quite important because it will act as pre-fatliquoring and maintaining the smoothness, improve plumpness, and improving tensile strength. Best combination for very soft, fluffy, and buttery feel leather will be Phosphonol LHE ( full synthetic good penetrating and dispersing fatliquor ), Eurekanol 2012 ( natural sulfited based fatliquor, keep grain smooth and flat ), Yolkanol L5TC ( lecithin based fatliquor for good round and buttery softness ). Here stability of fatliquor is quite important, otherwise, we might end up with fat deposits on the grain. ( Sticky-greasy feel on the grain ). Some formic acid at the end of the process is beneficial for good exhaustion of fatliquors.
Why do we use more water in this washing operation?
By using more water, we are minimizing mechanical action, which might squeeze off loosely fix fatliquors and retanning chemicals from leather and might lead to empty and harder leather. 200% should be about the right quantity required.
What is Alloderm Black BDD?
Alloderm Black BDD is a very special designed carbon black pigment that had been milled to particles of single digit nanometer. This pigment will help fill in the minute opening on leather like old scar marks or wrinkle grooves along the neck and shoulder. These wrinkles grooves and almost impossible to cover with dyestuffs in drum dye black leather. ( The wrinkle grooves will either be darker or lighter than the rest. ) Alloderm Black BDD will help to equalize the differential shade effect.
What’s the dosage of Alloderm Black BDD?Since covering of Alloderm Black BDD will depend on surface area, which means more will be needed as the leather gets thinner and vise versa, less will be required when the leather is thicker.
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What do we have to watch out for when we are using Alloderm Black BDD?
Alloderm Black BDD is a dispersion type of carbon black pigment, if there is any presence of dispersing chemicals like syntans and extracts, or syntans in enough quantities, exhaustion of Alloderm Black BDD will be strongly affected. (floats will always stay black regardless of running time)
What shall we do, if we want to apply Alloderm Black BDD in heavy retanned leather?
How can one determine whether or not Alloderm Black BDD is well taken into leather?
After about 20 minutes of running of Alloderm Black BDD, the float should be clear.
What is Yolkanol 104 AL?
Yolkanol 104 AL is multiple charged lecithin fatliquor that will assist proper exhaustion of other fatliquors. It is very beneficial when one has to increase fatliquor dosage or in the case of vegetable tanned leather, where it’s impossible to exhaust anionic fatliquors.
Why do we need topping with dyestuff?
We found that topping of dyestuffs at the end of operation will greatly contribute to the color intensity of dyestuffs.
What is Silikanol S2733D?Silikanol S2733D is reactive silicone dispersion, when used at the very end of operation will greatly improve on the plumpness and suppleness of leather grain. Since this is cationic in nature, care must be taken to wash thoroughly as possible from anionic chemicals before application of Silikanol S2733D. Like wise, leather after fatliquored with Silikanol S2733D should not be sammed of set out right away or in very wet conditions because such operations might force out loosely fixed Silikanol S2733D in the leather. Best is to horse up until leather is dry enough before further operations like setting out.
How does one determine whether one’s leather is dry enough for subsequent operations?Rule of thumb is to fold leather, flesh to flesh, and squeeze. If water coming out appear like sweats, then the leather is dry enough for further operations.
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