SINTEVA is a stable and sustainable synthetic leather suitable for leather conservation. This is an ongoing research.
Peer-reviewed : Perrine de Fontenay (painting conservator), Claire Valero (paper conservator)
Below you will find the questions concerning SINTEVA raised during the ICOM-CC intervention in june 2019. Please find the link to the conference presentation here: SINTEVA Poster 2019 Quai Branly ICOM-CC
You can ask any question you would like in the comment section at the bottom of this article, and we will get back to you as soon as we are able.
Click on one of the questions to access the answer :
BACKGROUND & GENERAL
What is SINTEVA ?
What is SINTEVA made of ?
Why the name SINTEVA ?
From where did this idea originate ?
What are we looking for when trying to find an alternative material for bookbinding conservation ?
Why focusing on BEVA 371 ?
Why did you use BEVA 371 instead of – say, Lascaux 498HV or acrylics ?
So what modifications make SINTEVA ?
What could the drawbacks of SINTEVA be ?
The use of BEVA 371 with leather is nothing new. Why is SINTEVA innovative ?
I am not convinced with the plastic look of synthetic leather.
Is there any risk of dye bleeding ?
What about PINATEX ?
Where can I buy SINTEVA ?
Can I sell SINTEVA ?
I am a student and I wish to test or use SINTEVA for my MA research
I wish to participate in the development of the research but I am not sure how ?
Can I get a sample ?
Q : What is SINTEVA ?
A : SINTEVA is a sustainable and stable synthetic leather that can be used for leather conservation as an infill material.
Q : What is SINTEVA made of ?
A : SINTEVA is composed of modified BEVA 371 Solution. A combination of added components, a specific application, as well as the Solution’s film-forming capacities, allows for a leather patterned film to be obtained.
BEVA 371 is an ethylene vinyl acetate-based solution in form of a transparent gel. It was created by Pr Gustav Berger in the 70’s as an alternative to wax consolidants for canvas in the conservation of easel paintings. This is what SINTEVA research is based upon.
Q : Why the name SINTEVA ?
A : The name SINTEVA designates any finished or prototypic synthetic leather issued from this specific research. It was chosen in order to facilitate discussion terms and avoid any confusion, as many subtleties and contradictions are already present in this specialised field of conservation.
This name has its source in two areas, firstly to link it to our ethical concerns with latin assonances of silva (nature) and synthesi (elements of same nature put together), and secondly in the main component BEVA 371.
Q : From where did this idea originate ?
A : As a paper conservation student, I had the opportunity to be an intern in well-known conservation labs and science departments. However, though these places were the cornerstones for both innovative methods and the practice of historical bookbinding, I soon understood that there was no real consensus concerning conservation methods for books. This undiscussed disagreement resulted in a division caused by the absence of standardization and therefore a lack of tracability of methods – which is essential to conservation.
As a student, I was therefore confronted with a problematic situation where I was expected to yield results, but by employing contradictory methodologies. This prompted me to develop my own philosophical approach to the field before my career even started. My new ideas were backed up by my additional experience in France, where the tradition of bookbinding has particularly deep roots and, as a consequence, the topic of repair is rarely brought up during discussions.
With the idealization that comes with young age, I began imagining a product that would make everyone agree. Of course, as I started my research, I soon understood there was no such thing as a unique path, and that it was not even something to wish for as far as conservation is concerned. But wishful thinking at least led to an alternative. With alternative comes options, and with options comes the choice to reconsider our practice for the best.
Q : What are we looking for when trying to find an alternative material for bookbinding infills ?
A : Traditional methodology implies the use of modern leather, which often shows an alarming rate of deterioration after less than ten years due to acidic tanning emissions, hydrolysis and dyes disgorgement. In addition, suppliers rarely provide any transparent information as to the tanning process of leathers.
The conservation practice also proceeds with the removal of original leather to slip infills under torn edges. There lies a paradox, as this invasive process and the location of the infills – the joints, are usually the most exposed and thinned down parts.
Alternatives have been found in Japanese paper pasted with cellulosic adhesives and toned with non-diluted acrylics. This technique is dubbed as “neutral” by most professionals in paper conservation, whereas users of the new-leather-infill method considers the Japanese paper repairs to be unaesthetic and fragile.
This was not something we intended to deny, but when working for this research to assess the physical strength of SINTEVA, we found that Japanese-paper-repairs samples were 10 times less resistant folding endurance tests compared to those of standardized samples of SINTEVA (version with modified BEVA 371 solution and no lining).
The Japanese-paper-repairs samples also developed wrinkles along the fold in the ten first folds, while SINTEVA goes back into place after 4000 folds in average.
This fragility of Japanese tissue repairs is something other specialties – such as leather conservators – accept the consequences of because the lack of alternatives forces them to turn a blind eye to the drawbacks of this technique.
Luckily, this has been evolving recently, and more and more discussion takes place internationally to avoid those issues.
The full test results are published in « (2018) BEVA® 371-based Synthetic Leather, Journal of Paper Conservation, 19:1, 18-32, . Please get in touch if you are unable to consult the article – Contact page
Q : Why focusing on BEVA 371 ?
A : BEVA 371 has already been subject to studies in the context of leather conservation in ethnographic and naturalist collections. The results came extremely positive in terms of light and heat ageing and compatibility with leather. Indeed, BEVA 371 showed no sign of deterioration in artificial ageing or in three decades of contact with degraded leather (Kronthal 2003).
This research gives evidence that BEVA 371 could in fact have potential in the role of an infill for leather.
However, there is more research to be done concerning its physical properties under strain – since it was not a material designed specifically for mechanical purposes (in the sense of externally applied forces).
Therefore, the development of SINTEVA involved enhancing the physical properties of BEVA 371 in order for it to be applicable in leather conservation, through chemical modification, and testing different prototypes under tensile strain.
Q : Why did you use BEVA 371 instead of – say, Lascaux 498HV or acrylic paintings ?
A : Unlike general belief, Lascaux 498HV does not have good reversibility unless it’s being intensely heated, action which is strongly discouraged in relation with leather conservation.
As for acrylic paintings, even though it is widely used in book and paper conservation, there are a few misconceptions regarding their ageing, which is actually still not completely verified.
Both materials have a tackiness to them and a plasticized aspect. Acrylic paints may be reversible with a Japanese paper support, but it is easily worn and it also jeopardise the Japanese paper flexibility through penetration of the fibers, even when undiluted.
Q : So what modifications make SINTEVA ?
SINTEVA enhances the physical properties of BEVA 371 in order for it to be applicable in leather conservation, through chemical modification and testing different prototypes under tensile strain.
A : The research involves improving the solution’s physical properties by modifying the structure with several compounds. In order to do so, the solution is heated on a double-boiler to its melting point, and the compounds are added in order to modify its structure, and thereby improve its tensile strength. The hot solution is then laid in a mould, so it may set into a semi-hard film with a follicular surface.
The addition of microspheres to the solution has been the most successful so far. Microspheres (or phenolic microballoons) are used as inert aggregates to strenghten fillers. They are small and hollow spherical microparticles, with diameters typically ranging from 1 μm to 1000 μm (1 mm), that can have several origins, such as poly ethylene. However, because the BEVA 371 solution was heated at high temperatures, glass microspheres were prefered instead.
The hollow structure of the microspheres aerates the solution and enhance its flexibility. Microspheres improve SINTEVA’s capacity to withstand folding, and not bear any mark of it. They also slow down the drying process and evens the evaporation of solvents, thus avoiding retraction and distortion of the film – which is usually impossible without slow setting with heat. We found that they also help with getting more precise patterns during the follicular surface imprinting process.
Q : What could the drawbacks of SINTEVA be ?
A : Like any material, SINTEVA will eventually deteriorate, but so far, it has proved to be much more stable and compatible than other known alternatives. We have more than 30 years of real-time observation to say that BEVA 371 is compatible with leather conservation, and three years of accelerated ageing to back this information.
The glass microspheres have been the most successful addition so far; especially reassuring is the fact that they are inert by nature.
However, SINTEVA will continue to evolve and be improved upon, for example through testing of different proportions of the modified solution.
Q : The use of BEVA 371 with leather is nothing new. How is SINTEVA innovative ?
A : BEVA 371 was designed as an adhesive for paintings. It was used with that same intent on leather in ethnographics and naturalists collections by filling gaps with melted film, to consolidate and fill. It is true these experiments already involved the addition of microspheres to add strength to the repair, or that they were coloured with pigments.
However, none of the additives were quantified. Melting was systematic and in-situ, with no way to measure the temperature or target-control the dripping. Considering the melting point of BEVA 371 (MP > 68°C) and the denaturation of new leather (80-90°C), let’s face it, using melted BEVA 371 on leather is an irreversible process. The 2003 CCI research stated just so, explaining that the research was a success as far as the lab experiments were concerned, and no degradation was observed with BEVA 371 on leathers after 30 years. However, it pointed out that the only failures were the darkened areas where melted BEVA 371 had been inappropriately handled and the solution had seeped into the leather.
SINTEVA would not exist without the creation of BEVA 371 and these later experiments with leather. SINTEVA deserves a brand new name as it is an innovative twist because it does not use BEVA 371 for its adhesive properties, but for its compatibility in relation with leather. The fact that SINTEVA is not just a cohesive link anymore, but becomes a whole material in itself, defines its novelty from the state of adhesive to a finished product. The infill is not melted on the artefact anymore, but prepared beforehand and adhered to leather according to conservation standards.
The fact that SINTEVA is not just a cohesive link anymore, but becomes a whole material in itself, defines its novelty from the state of adhesive to a finished product.
Q : I am not convinced with the plastic look of synthetic leather.
A : Your desires are ours ! We don’t like this either. Problem solved, SINTEVA has an aerate structure and therefore, it does not have a plastic look thanks to the modification of the components. It can even imitate suede with the proper structure modification.
Q : Is there any risk of dye bleeding?
A : Unlike leather, SINTEVA is not coloured through dyeing, but with the addition of raw pigment suspended in the solution. As such, pigments are trapped. Further testing will include the compatibility and proportion of certain pigments in the solution.
If you are a professional and wish to participate in this testing, please feel very welcome to contact us.
Q : What about PINATEX ?
A : Some of our first SINTEVA prototypes included a cotton canvas backing to reinforce the structure of the follicular patterned surface made with modified BEVA 371. It gave even more strength and thickness to SINTEVA, so it could be used for special projects.
Research has been done from very early on for an alternative of this cotton canvas backing that would resemble leather more. This is how we first heard about Piñatex ®, a vegan leather surrogate, made with pineapple fibers and PLA. Developped in the past few years, it has passed all ISO standards, and became available for sales in 2018. The nature of its structure with long fibers and cellulose binding makes it more compatible with leather conservation compared to the square structure of canvas.
Please reach out if you want to know more about this side of the research, or if you want to test the advantages and drawbacks of Piñatex and its compatibility with leather.
Q : Where can I purchase SINTEVA ?
A : SINTEVA is not yet available for commercial purchase. The research is still fairly new, but we are working towards making it available as soon as possible.
Q : Can I sell SINTEVA ?
A : At this time SINTEVA holds an international patent to give us some time to make extra testing. We’d rather take time to be absolutely certain that the product we sell is a product every conservator can trust before rushing into sales. However we are extremely interested in partnerships and we think working with other people leads to further improvement.
Q : I am a student and I wish to test or use SINTEVA for my MA research
A : You are most welcome to do so ! This research started through an MA thesis, and we believe that supporting each other is part of the job. Please note that SINTEVA is copyrighted, so you must warn us if you intend to use the research for your own work. The patent guarantees that only quality and sourced information is shared, and that there is no misunderstanding of what SINTEVA is.
Q : I wish to participate in the development of the research but I am not sure how ?
A : Thank you, your interest is most welcome ! As the French put it : « Little streams make big rivers ». You can help us by spreading the word about SINTEVA, share this Q&A, and if you have any other question, please ask us through the comment section below. Who knows what the outcome might be ?
SINTEVA already received a generous funding from a sponsor which allowed us to develop the first prototypes, speak at the 46th Annual AIC Conference (Houston 2018), and publish a lengthy article in the Journal of Paper Conservation (2019). SINTEVA is a self-financed research by one conservator, parallel to a private conservation practice. Any help is welcome and will help us make SINTEVA available as soon as possible !
Q : Can I get samples ?
A : We usually make samples on the occasion of a conference. Any sample left can be sent to your address. We advertise when there is a possibility to get samples, so please follow us on Twitter and make sure you get the next ones !
Due to repeated demands, we feel the need to specify that the samples we provide are, well… samples !