Posted: 28 February 2010 at 2:04am | IP Logged

Is that increase of solubility of MgO caused by derivated sulphate ion from chrome?

I believe solubility character of Ca and Mg can not be changed by acid condition ie shape of curve can be changed but dirction can not be changed.

Posted: 15 March 2010 at 1:36pm | IP Logged

Let me quote a paragraph of one of Ramasami presentations, were size, in his view, is so important in the diffusion of tanning molecules. I think that to know the micro behavior of products in the drum is important but if we do not take in consideration SIZE EXCLUSION, it is but wishfull thinking.

APPROACH TOWARDS A UNIFIED THEORY FOR TANNING:

WILSON’S DREAM.

by T. Ramasami

JALCA Vol. 96  2001 Pag.290-304

IMPORTANCE OF DIFFUSION PROCESSES IN TANNING(pg293)

Diffusion phenomena of tanning into a skin matrix would be influenced by  a variety of factors. An attempt has to be made to identify and summarize various factors. Understanding of various factors associated with diffusion  phenomena involved in tanning is fundamental. Materials and molecules need to be transported into the skin matrix and pentafibrilar assembly.

Such a mass transport  involves the penetration of materials through micro-, meso-, and macro-poric  structures of the frame work system of collagen.

Theses factors are listed in Table II. Where as many interactions of collagen with tanning molecules may limited by diffusion, some elementary steps will be  by rates of reaction.

In development of a the unified theory for tanning, it is necessary to delineate diffusion-limited processes from reaction controlled  pathways. If the pentafibrillar assembly is considered as the main reactant, molecular size controlled diffusion phenomena cannot be ignored. Majority of theoretical treatments of tanning have considered the molecular size of  species involved in tanning are small and the access to relevant functional sites in protein is not limited.

If protein sites in within the polar cavity of  the pentafibrillar assembly were to be considered as sites of reaction, it is conceivable  that mayority of molecules involved in tanning may not easily gain access. Many  Chromium(III) species contained in basic chromium sulfate bear sizes larger than 7 A.

They may be too big to access sites within the inner cavity of the pentafibril.

I have to include again my " pretty pictures " because I am not a man of words but of images, and I have to visualize in my head, at least  in part, of what could be going on in there.

I hope this does not fall in to the category of:

The highly theoretical interpretation of esotheric technology...

Reagrds

Zercas

Posted: 15 March 2010 at 4:40pm | IP Logged

I am not prepared enough to expound on dimensions of the entering tanning agents, nor their achieved size after tannage reactions are finaly acomplished,  but being a man that learns from other people's words, I quote from BASF's book "From Collagen to leather...."  on page 100:

"Küntzel was then able to demonstrate by studies of the fibre birefringence that collagen-tanning agent interaction was not restricted to the fibre surface, as originally postulated by the absorption theory, but a reaction ("permutoid" according to Freundlich) takes place, as a function of the particle size of tanning materials, through to the innermost regions of the collagen  microstructure, about which little was known at that time."

    I understand that the collagen's microstructure is basicly the triple helix called tropocollagen and its chemically reactive  groups do react with chemical agents especially if these  "jello" strands are loosely but extensively bound helicoidally primarily by H-bonds and secondarily by weak, but multiple saline links, and not by highly rigid structured covalent bonds.  I am not offering for general consumption an analogous concept to "unified-field-physics-theory" type tannag e theory for all modalities, as of yet, and I do also believe Dr. T. Ramasami was not either!  I understand that Dr. Ramasami was expressing his faith that a unified modality tanning theory would eventually arise with better understanding.  This view I express, does not say that there are not higher hierarchical structures that exist and determine many physicochemical aspects of leather.  Nor do I maintain that there are no covalent bonds at all, but accept the importance of a few joining the ends of tropofibrils in the staggered arrangement composing fibrils.

   I do understand that there was a long time ago a proposal for a tanning theory based on a surface coating of fibers by polimeric materials that fell into disacceptance and was referred as an absorption theory, which perhaps still explains resulting softness in leather upon drying, but not per se hydrothermal shrinkage temperature increase by true tannage.

Posted: 18 March 2010 at 1:33pm | IP Logged

That theory by Knapp was from 1919, in those times they did not have the tools that there are today at hand, and I belive Knapp was not to far from the truth, just look at this recopilation of ideas from researchers in China, they are retaking some past ideas like the ones from Waldo and Hernandez and thinking out of the box, they have acomplished 140+ C  Tc with Salicylates and metals,  Cr and Al.

http://www.chinaleather.org/download/2-1/2-6.pdf

http://cat.inist.fr/?aModele=afficheN&cpsidt=20247361

But Ramasami's work on The Unified Theory has to be look more closely, the main issue is what really determins tannage, Tc or Collagenase resistance. You can have high Tc and enzymatic degeneration, which goes in the direction of SIZE EXCLUSION. Call it like you like but if you "coat"  far out from the penta fibril, you may have high TCs but not Collagenase resistance.

Regard

Zercas

Posted: 18 March 2010 at 4:51pm | IP Logged

 Ramasami's presentation name: " Aproach Towards a Unified Theory of Tanning: Willson's Dream" , reflects the idea (dream ) that leather should be material that after completed the manufacturing process, should be a " stable product ", big word I know, but there should not be problems like these. ( Please look at the attachment at the bottom )

What made that leather so suseptible to fungus?  The collagen fiber not well tanned? The fatliquors that atracted the fungus?  What else? 

I know that this case could be one in many, but I have been there, while tanning sole leather, fungus and bacteria just pop up enywehre and you have to be on your toes not to have the whole tanyard aver taken by the bugs. One solution, even tough not intended, was a jump from pits to all drum system. But the real difference was the pretan with a chrome complexed outside the drum, very small particle size, that I believe went in very deep and that combination tannage diminished the bacterila and fungus growth in the whole area.

That is why I have insisted in the SIZE EXCLUSION in all this discussion, we have to racionlaize where do we want our product to go and " remain". As tanners we do nt have the luxury to have those wonderfull tools to look deep inside the fiber, so if you gather " theoretical interpretation of esotheric technology...", from where ever you can, what is wrong with that.

Research is mainly done in your head, so the more input you give to that wonderfull biocomputer that is our brain, the more clear we can do things. Oh, I know,  you maybe not taken seriously by the big shots that write bit papers, but if it solves your day by day problems, who cares

Regards

Zercas

No compensation in DMF row

More than 300 consumers in the UK who suffered skin reactions after buying furniture from now-defunct retail chain Land of Leather will receive no compensation, the High Court has decided.

At a hearing in London, the judge ruled that Land of Leather's insurers, Zurich, should not have to pay compensation. Zurich argued that Land of Leather's decision to source leather sofas from only one manufacturer in China, in this case Dongguan-based LinkWise, breached the terms of its policy with the retailer.

The reaction on people's skin was caused not by the leather or the furniture itself, but by anti-mould agent dimethyl fumarate (DMF). The International Union of Leather Technicians and Chemists Societies (IULTCS) has made it clear that, to the best of its knowledge, the DMF problem is not from the leather. DMF is not used during the manufacture of leather articles, but it was placed in sachets that were put inside furniture, shoe boxes or other packaging material to inhibit mould that could otherwise harm the products during transport and storage.

IULTCS has said the fungicide is not used by any tanneries, and has not been used by the tanning industry to preserve finished leather.

Nevertheless, more than 4,000 people in the UK have experienced skin allergies, rashes and burns after using leather sofas bought from Land of Leather and two other retail groups, Walmsley Furnishing and Argos. EU manufacturers were already banned from using the chemical, and, on March 17 last year, the EU made a formal ruling (2009/251/EC) that prohibited products containing DMF from being made available on the market in the EU after consumers in at least five member states suffered skin burns and breathing problems due to the chemical.

Although all three UK retailers had previously admitted liability, Zurich announced in March 2009 that it would not provide insurance cover for Land of Leather claims.

Richard Langton, senior litigation partner at Russell Jones & Walker, the solicitor who is leading the group litigation against the retailers in question said: “This is a devastating blow for victims who purchased their sofas from Land of Leather, all of whom believed for almost 12 months that Zurich were going to pay out. A group of over 300 innocent people who sustained in many cases severe injuries, due to an admittedly faulty product, will receive no compensation. Consumers must beware that buying products made in China is potentially dangerous and if something goes wrong they have less chance of redress. Zurich’s delay in notifying us added insult to injury by making our clients believe they would be paid. Unless this decision is overturned on appeal a great injustice will have been done.”

The case continues for the several thousand customers where insurance cover remains in place. The court will look at a number of test cases in May.

Posted: 18 March 2010 at 7:31pm | IP Logged

Man, you can Google-it almost any thing, everything is at your finger tips 

http://www.springerlink.com/content/9h6w78333n706451/fulltex t.pdf?page=1

Regards

Zercas

Posted: 18 March 2010 at 10:33pm | IP Logged

WOW, I think that a method like this on the X-Molecules of tannins would be great to find out somehow the species of chrome IN THE PERIPHERY OF THE PENTAFIBRIL.

http://www.biochemj.org/bj/218/0229/2180229.pdf

Just pondering some  " theoretical interpretation of esotheric ideas". And about those " burried carboxylics" of the "Jell-O strand" are going to be burried if the size of the tanning molecule is not small enough; my feeling is that Ramasami is correct when he says that some of the chrome species react with the pentafibril, the periphery of that structure. Looking at the above figure in the previous posting, the carboxylic on the " blue strand" are going to be very difficult to reach. Of course there is a "twist"

Regards

Zercas