JW Latex Consultants (and Rubber Consultants,乳胶顾问) offer solutions to your problems in Natural Rubber latex and Synthetic Rubber latex processing and the manufacturing of latex products (condoms, catheters, medical gloves, baby teats and soothers, toy balloons etc) Quick answers through e-mails are possible at reasonable cost.



[Advantages of Prevulcanization] [Air Permeability] [Applications of PV Latex] [Bacteria and Latex] [Chemical Toxicity] [Cross-Linking Density] [Biodegradability] [Black Articles] [Blooming] [Bouncing Ball] [Compression Set] [Condoms] [Copper Staining] [Creaming] [Defoamer] [FDA] [Fatty Acid Soaps] [Flame Retardant] [Flocking] [Food Packaging] [Glove Demand] [Glove Discoloration] [Glove Selection] [Guayule Latex] [History of Gloves] [Joul Effect] [Lab Equipment] [“Latex” Definition] [Natural Rubber Latex Stability] [Natural Rubber Latex Thread] [Milling Problem] [Mixing Equipment Directory] [MREPC Articles] [Nano Polymer Particles] [Nano ZnO] [Permanent Set] [Polychloroprene] [REACH] [SMG] [Storage Hardening] [Stress Relaxation] [Surfactants Directory] [Tensile Properties] [Vulcanization] [Vytex] [Yulex]


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Monday, March 20, 2017

Why Does Dilution of Natural Rubber Latex Cause Latex Detabilisation?

Manufacturer: We always encounter coagulum problem when we dilute our NR latex compounds with water. Why is this so? Please help!

John Woon (Senior Latex Consultant): If your latex compounds are well stabilised with sufficient soaps/stabilisers, dilution with water generally would improve the latex stability.

I believe your latex compounds are not properly stabilised and when water is added, the concentration of stabilisers present in the water phase is reduced, hence a reduction of latex stability leading to the formation of coagulum.

What you can do is to add some stabiliser (similar to that used in the latex) to the water before dilution.

Sunday, March 05, 2017

Second Edition of "Practical Latex Technology" Launched!

JW Latex Consultants are pleased to announce the launch of our Second Edition of the 159-paged Ebook, "Practical Latex Technology" with more additions of Q&A.

It contains answers to more than 150 questions plus other very useful tips and ideas!

For easy of reference, it is divided into 5 Parts:

Part 1: Vulcanisation
(Vulcanization), Vulcanisation of Latex and Prevulcanised Latex
Part 2: Properties of Rubber
and Latex
Part 3: Problems of Latex
Processing and Finished Products
Part 4: Compounding Ingredients
and Processing Aids
Part 5: Miscellaneous Subjects

Get your copy for a one-time investment of only $85.00!


Practical Latex Technology - 2nd Edition

Please contact john@jwlatexconsultants.com and woonsungliang@yahoo.com.sg if you have problem in downloading the ebook.

Sunday, February 12, 2017

Thickeners for Natural Rubber Latex and Nitrile Latex

Manufacturer: We are manufacturing latex dipped products based on both Natural Rubber latex and NBR (Nitrile) latex. Please advise us on the types of thickeners we can use.
John Woon (Senior Latex Consultant): You can try the following:

1) Natural Colloids
Examples for theses are casein and alginate. Ammonium casienate (10% solution of casein in ammonium hydroxide) and sodium alginate (5 - 8% solution) have been used successfully in the industry. However, these are prone to bacterial attack. I suggest you add some bactericide.

2) Celluloses
Widely used cellulose types of thickeners include methyl cellulose, hydroxy propyl methyl cellulose and sodium carboxyl methy cellolose and their derivatives with chemical modifications. All are used at a concentration of 4 to 6%. They are available in different molecular weights giving different viscosity accordingly.

3) Polyacrylates
Examples are ammonium polyacrylate, sodium polyacrylate and polyacylate acid emulsion. When using the acid emulsion care must be taken to prevent possible flocculation of latex.

4) Water-soluble polyurethane 
This is an alkyl phenol ethoxylates associative polyurethane thickener widely used in the coating industry.

Monday, January 23, 2017

Happy Chinese New Year!

Chinese New Year, also known as Spring Festival in China, is the most important traditional holiday for all Chinese. Chinese New Year 2017 is on Saturday, January 28th, 2017 i.e. the first day of the Chinese lunar calendar.

 Mr. John Woon of JW atex Consultants would like to send his visitors a beautiful Chinese New Year Card. Please view the card in the following link:


Sunday, January 22, 2017

How to Obtain Small Natural Rubber Particles for Textile Impregnation?

Manufacturer: We are manufacturing textile and similar products treated with natural rubber latex. We understand that one of the criteria of good penetration and impregnation of the rubber into the textile is the rubber particle size in the latex i.e. we need small rubber particles.

We have been told that in the normal centrifuged latex concentrates, the inherently smaller rubber particles of the latex have been removed by the centrifugation process. My question is how and where do we obtain such small sized rubber particles which are originally present in the latex?

John Woon (Senior Latex Consultant): Good question! Though it is possible it is costly to recover the small sized rubber particles from the skim after the centrifugation of field latex to obtain the concentrated latex.

Fortunately all is not lost because latex concentrates made by evaporation process are commercially available from Revertex Malaysia (Synthomer). In the evaporation process, only water is removed from the latex hence the inherently present small rubber particles are not removed, unlike the centrifuged latex.

Also, these evaporated latex concentrates have excellent mechanical and compounding stability besides having excellent penetrating property. They are available with 68% and 73% TSC.

How to Minimize Copper Staining While Maintening Dithiocarbamates in the Compound Fromulations

Manufacturer: We are a medium sized factory manufacturing latex thread and other dipped products. In one of our products we would like to minimize copper staining. We also want good heat resistance. However we do not want to replace dithiocarbamate in your latex compound. What shall we do?

John Woon (Senior Latex Consultant): It is not easy to prevent copper staining without removing dithiocarbamates from your latex compound formulations. However, I have the following suggestion to control the staining:

1) Try reducing the level of dithiocarmate to the very minimal while adding a thiazole (ZMBT) as the main accelerator. The reduced level of dithiocarbamate is such that it still gives you reasonable rate of vulcanization and physical properties of the final products.

2) If you are using ZDEC, replace it with ZDBC as the latter has lesser tendency to cause migration staining.

As for heat resistance, you can try sulphur donors such as TMTD, DPTT or Morpholine disulphide in conjunction with thiazoles.

Thursday, December 29, 2016

How to Improve Setting of Latex in Straight Dipping?

Manufacturer: For some technical reason requested by our customer we can't use coagulant dipping. We were advised to use only straight dipping. However we encounter excessive latex flow from the former due to poor setting of the latex in the oven. Do you have any tips to overcome this problem?

John Woon (Senior Latex Consultant): Here are some tips you can evaluate:

1) The latex compound must be well matured before use. I'm assuming you are using post-vulcanisable latex compound.

2) Control the latex compound viscosity.

3) Make the latex slightly heat-sensitive by controlling the formation zinc-ammine complex with ZnO and alkali.

We would like to wish our friends, customers, students and clients "A Very Happy New Year!"

Sunday, December 11, 2016

How to Transfer Latex Without Latex Destabilisation Due to Mechanical Shear

Manufacturer: We are manufacturers of latex products using natural rubber latex. We always encounter coagulum formation problem when we transfer latex from tanks to tanks. Please advise us the best way to transfer latex without latex destabilization problem.

John Woon (Senior Latex Consultant): One could transfer latex from one container to another by using pump, compressed air or gravity. While pumping might destabilize the latex, compressed air and gravity feeding have the least destabilization problem. When using pump, care should be taken to select one that gives the least mechanical shear to the latex.

For compressed air feeding, one must use pressure tested and insured tanks and a supply of clean compressed air. Therefore this more expensive method is mainly used for bulk deliveries of latex.

Transferring latex by gravity is the cheapest and simplest to use while preventing mechanical shear to the latex and therefore the chances of coagulum formation are kept to the very minimum. However the factory layout must be designed in such a way that the storage tanks are located on an upper floor or level to allow the latex to flow down to the compounding tanks situated at a floor lower. From the compounding tanks, the compounded latex is in turn allowed to flow to yet another floor lower for further processing such as dipping, casting or extrusion, etc.

Saturday, November 19, 2016

Natural Rubber Latex - Problem with Dilution with Water

Manufacturer: We are latex gloves manufacturer. We always encounter latex destabilisatiion whenever we dilute our latex compound with water before dipping. This has resulted in high loss and poor processing. Can you explain why?

John Woon (Senior Latex Consultant): One possible reason is the fact that when water is added to the latex compound, the concentration of latex stabiliser present in the water phase is reduced accordingly. Therefore you should add a small amount of the stabliser in the water before using it.

Also, you must prevent "pH shock" to the latex by adjusting the pH of the eater to about 9.50. It is advisable to use deionised or softened water for latex dilution to prevent destabilisation of latex by free calcium and magnesium ions.

Tuesday, October 25, 2016

Discoloration of Rubber Products

Manufacturer: We are manufacturer of latex casting and dipped products for medical applications. Very often, we encounter discoloration of our products. Please advise us how to overcome this problem.

John Woon (Senior Latex Consultant): Discoloration is an unwanted and undesirable change of colour of light-coloured rubber products especially white toy balloons. However, it is very often confused and misunderstood by many latex products manufacturers.

It can be caused by compounding formulation (ingredients), processing and storage or service conditions. Different causative factors would require different remedial actions to overcome them.

The following are the possible factors causing the discoloration of toy balloons:

1) Based Latex

2) Compounding Ingredients

3) Processing (curing and leaching)

4) Storage and Service Conditions

In response to your request, the details have been sent to you separately.


Friday, October 21, 2016

JWLatexConsultants.com Infected!

John Woon (Senior Latex Consultant):
Please be informed that our sister website, JWLatexConsultants.com has been hacked and infected. For your security, please do not visit this site for the time being. We apologize for any inconvenience caused.

You are welcome to visit our sister website at http://woonsungliang.wix.com/jw-latex-consultants

Wednesday, September 28, 2016

Natural Rubber Latex Adhesives vs Solvent Based Adhesives

Manufacturer: My company is manufacturing rubber-based adhesives. Recently I was asked to venture into natural rubber latex based adhesives to replace some of our solvent based adhesives. What are the general advantages of latex based adhesives?

John Woon (Senior Latex Consultant): Generally, while latex based adhesives are environmentally friendly, it also offers the following advantages over the solvent based adhesives:

1) Latex has a low viscosity at high solid content. For instance, NR latex concentrate with a total solid content of about 60% has a viscosity of only 150 to 200 mPa.s whereas a rubber solution of about 17% has a viscosity of 60,000 to 100,000 mPa.s.

2) The low viscosity of latex allows it to be easily applied by spraying and roller coating.

3) The high solid content of latex allows for high coating weight  (dry) to be achieved with minimal number of coating.

4) For solvent based adhesives the rubber is frequently masticated to breakdown of the rubber molecules before use to ease dissolution in solvents. This results in the weakening of the cohesion strength of the adhesives. Latex based adhesives do not have this problem.

5) Owing to the absence of solvent, latex adhesives do not pose as health and fire hazards. There is no need for expensive procedures and precautionary actions such as the use of flame-proof motors, maximum ventilation, flame-proof lighting and segregation from other production processes.

Tuesday, September 20, 2016

Continental Brings Dandelion Rubber to Commercial Vehicles

According to Rubber World, a technical revolution is now available for commercial vehicles. Continental is for the first time unveiling components and tires for trucks and buses made from natural rubber derived from dandelion roots.

At the forthcoming International Motor Show Commercial Vehicles, the technology company will be showcasing for the first time truck tires made from this innovative and sustainable dandelion rubber: Conti EcoPlus HD3, which were manufactured in summer 2016.

On show will be also the prototype for an engine mount that links the power train with the chassis. This insulates the structure-borne noise from the engine, thereby enhancing ride quality and driver safety.

Another sampled product will be the first example of an intermediate propeller shaft bearing made from the new material, named Taraxagum. This stabilizes and minimizes the transmission of vibrations to the chassis.

As an agricultural crop, dandelions have the potential to become an alternative, environmentally friendly raw material source, thereby helping to reduce our dependency on traditionally produced natural rubber. But that is not all: The plants can be cultivated in northern and western Europe, which makes transportation routes to the European production sites much shorter and contributes to the sustainable use of existing resources. Continental has already recognized this potential, and as early as 2014 launched the first premium winter tire featuring a tread made from pure dandelion rubber.

Tuesday, August 30, 2016

Compounding for Low Temperature Applications of Natural Rubber Products

Manufacturer: We are manufacturers of a range of natural rubber based products intended for applications at low temperature during winters. However, we have not been very successful because the products tend to harden at low temperatures. Please give us some clues on how to overcome this problem.
John Woon (Senior Latex Consultant): Owing to the stereoregularity of the natural rubber molecules, the rubber tends to crystallise and lose elasticity with increased stiffness when subjected to  proloned exposure to low temperatures.

I suggest you conduct some experiements by increasing the levels of sulphur and accelerators, particularly sulphur. Adding a plasticizer such as di-iso-octyl sebacate, would be advantageous. Replacing some of the natural rubber with "super processing rubber" made partially from prevulcanised latex such as PA 80, could also heelp.

Friday, August 05, 2016

Technical Papers to be Presented in the 8th International Rubber Glove Conference and Exhibition in Kuala Lumpur , Malaysia

The papers confirmed for the 8th IRGCE 2016 ( from September 6 - 8, 2016) are as follows:
  1. Beyond The Horizon: Longer Term Opportunities of the Rubber Gloves Market by No Dock Moung of ICIS Consulting Asia, Singapore
  2. Novel Room Temperature Safe Cure Compositions for Use in Synthetic Polyisoprene Latex by Ranvir S. Virdi by Robinson Brothers Limited, United Kingdom
  3. Important Changes in European Testing Requirements: EN 374-1, EN 16523-1, EN 420 and the new PPE Regulation by Martin Heels of SATRA Technology, United Kingdom
  4. Enhanced Process Effective and Skin Friendly Solutions for the Production of Dipped Goods using Synthetic Poly-isoprene Based Lattices by Adeline Kung of Kraton Polymers, Malaysia
  5. Insights into Film Deposition and Consolidation During the Thin Glove Coagulant Dipping Process by Dr Robert Groves and Dr Alex Routh of United Kingdom
  6. A Scientific Investigation on Extractable Residues in Various Rubber Gloves (Natural and Synthetic) by Dr Ng Thian Hong of Synthomer, Malaysia
  7. Attributes of Good Former in Glove Dipping Process by Howard Woon of Gateway Industrial Corporation Sdn Bhd, Malaysia
  8. Performance of Graphene Materials Incorporated into Latexes via the Conventional Mixing Route by Dr Mok Kok Lang of Malaysian Rubber Board, Malaysia
  9. Latex-T: A Rapid Diagnostic Test for Allergens in Natural Rubber Latex Products by Dr Roslinda Sajari of Malaysian Rubber Board, Malaysia
  10. State of Glove Affair by Denis Low Jau Foo of Malaysian Rubber Glove Manufacturers Association (MARGMA), Malaysia
  11. Use of Vulcanization Accelerator-Free Rubber Gloves in Patients with Rubber Accelerator Contact Dermatitis by Dr Kayoko Matsunaga of Fujita Health University School of Medicine, Japan
  12. Future Development of Alternative Sources of Natural Rubber: Guayule or Kazakh Dandelion by Dr Serge Palu of CIRAD, France
  13. Infection Control in Hospital Settings in Relation to Disposable Medical Products Particularly Medical Gloves by Patty Taylor of Ansell, USA
  14. Bio-add and Bactolex as New Additives for Biodegradable Natural Rubber and Nitrile Rubber Gloves by Dr Azura binti A. Rashid of University Science Malaysia, Malaysia
  15. Hydrophilic Polymers as Protein Removers for Natural Rubber Latex by Vijitha Dhanapala of Lalan Rubbers (Pvt) Ltd., Sri Lanka
  16. A Practical Approach to Making Nitrosamine & Nitrosatable Safe Latex Products by Anil Skariah of Thaimed Baby Products, Thailand
  17. Prospective Developments In Latex Products: Applications of Single Wall Carbon Nanotubes by Ekaterina Gorbunova of OCSiAL, Russia
  18. Conductive Rubber Films by Dipping Process by Dr Siby Varghese of Rubber Research Institute of India, India.
A half day seminar on "Analytical Methods for Latex Dipped Products" will be held on the 8th of September 2016 and to be conducted by Professor Dr Ho Chee Cheong and Dr Eng Aik Hwee.

Tuesday, July 26, 2016

Effect of Cross-linking - A Very Important Aspect of Rubber Technology

Students: We have just started our training course on vulcanization and cross-linking of Natural Rubber. Can you please let us know in general the effect of cross-linking on the behavior of the vulcanized rubber?

John Woon (Senior Latex Consultant):
Please see the Table above for the "Changes in Rubber Properties with An Increase in Degree of Cross-Linking".


What has the bouncing ball to do with tyres?

Latex Gloves Educational Articles from the Malaysian Rubber Export Promotion Council

How do you select your medical gloves?

Rubber Chemicals: Carcinogenicity, Mutagenicity, Clastogenicity.

Why is Compression Set measurement important?

Assessment of Latex Stability

Joule Effect

Poor Flocking Quality Of Household Gloves

Creaming of Latex

What is Vulcanization?

History of Latex Dipped Products

Applications of Prevulcanized Latex

Defoamer Creating Havoc in Glove Factory

Problems With Milling Rubber Chemicals

Medical Gloves From Guayule Latex

Introduction to SMG Gloves



Click on The Following Links to Read More Articles:

[Advantages of Vulcanization] [Applications of PV Latex] [Bacteria and Latex] [Chemical Toxicity] [Cross-Linking Density] [Biodegradability] [Black Articles] [Blooming] [Bouncing Ball] [Compression Set] [Condoms] [Creaming] [Defoamer] [FDA] [Fatty Acid Soaps] [Flame Retardant] [Flocking] [Food Packaging] [Glove Demand] [Glove Selection] [Guayule Latex] [History of Gloves] [Joul Effect] [Latex Stability] [Latex Thread] [Milling Problem] [MREPC Articles] [Nano Polymer Particles] [Nano ZnO] [Polychloroprene] [REACH] [SMG] [Storage Hardening] [Vulcanization] [Vytex] [Yulex]

The information and data contained in this site are believed to be accurate and reliable. However it is the responsibility of the visitors and readers to satisfy themselves that the information is workable under their own processing conditions. Hence the owners of this site make no warranties concerning the suitability of the information given in this site.