Covid Capers

Hi Everyone

Sorry about the title. Wasn’t trying to be funny or demeaning, but couldn’t think of a better title. It’s the most serious thing most people will be able to remember, or cope with.

What will it be like afterwards?  We probably don’t want to think about that yet – - let’s get through it first.

If anyone is interested at the moment I am still around but working from home. If anyone else is in the same boat …………… difficult to keep the concentration going isn’t it. If you want to get in touch my e-mail is or if you ring the office they will be happy to give you my mobile number. Allcocks are still open and the offices are manned as normal – ish

Let’s hope it passes safely for as many of everyone as it can.

Keep smiling


Careers Section. Addition to our web page

Hi Everyone           Another blog from Norman – November 2019.

Just to bring to your attention that we have added another section to our web page.

At the far right end (nothing political intended) of the menu bar you will now see the new section. It is labelled “Careers”.  Click on it and you will find a copy of the job advert we have just placed on “INDEED”.

This is a new idea to us and we hope, at a later date, to add some comments/ideas from existing staff – could be interesting. Of course we will be completely unbiased and only publish the good ones.

Please keep an eye on this new part of our site (as well as all the rest) as it might change quite quickly.

Cheers for now.


Customer Testimonials.

From Norman C. to all our friends out there.

It’s always good to blow your own trumpet now and again. It makes you feel good.

Well at least it me feel good. We have received some testimonials from customers and we thought it would be a good idea to share them. We always say that we are good at what we do, but it’s nice when other people say so.

a)         Having worked with Wellington Rubber for many years we have found their “Shred” to be a consistent, high quality product that is well presented. As a supplier they have always responded quickly, their “on time” delivery is good and the overall level of service is excellent.

b)          From John B.

It has been our great pleasure to have been able to conduct business with J. Allcock & Sons Ltd and Wellington Rubber Company Ltd for over 10 years. In that time, we have always found them to be a most reliable supplier, always willing to oblige where ever possible.

The information given is as expected from a quality supplier, attentive and willing to help, providing feedback and plausible reasons when the odd problem arises.     A successful partnership in business is highly reliant on the people within the organisation, it needs to meet each other’s expectations, the management team at Allcocks and Wellington Rubber excel in this field and therefore I would have no hesitation whatsoever in recommending their services and products.

c)          Tiflex Limited has a long association with J. Allcock & Sons. We have formed a great partnership with the Allcock team providing bespoke regrind materials to Tiflex specifications.

Orders are processed on time and to our delivery requirements and the prices remain competitive.     Business is conducted on a professional basis, delivered in a friendly manner and we anticipate many more years of a successful business partnership.

Well, there we are. I will pass more on as they come around.

Cheers everybody.

ISO 9001:2015 QMS certification.

Hi Readers,

Nearly Easter …… hope you have a good break.  Easter always signals that winter is over and better weather (hopefully) is on the way.

I have some great news to pass on.  Our QMS (quality management system) certification was due for renewal, so we took the bull by the horns and went for the new, latest version viz: ISO 9001: 2015.  It took quite a lot of work, by all concerned, because the “thinking” now has a different emphasis, but we did it.  We are now fully certificated to ISO 9001:2015, as from early this month.

Copies of our new certificate, either “hard” or digital, are now available to our customers.

As Matt has now moved on to pastures new (Good Luck Matt), I will be one of the contact points.  Please feel free to contact me.

Cheers for now



Taking a closer look – SEM Pictures of FKM Crumb

After a bit of good old fashioned arm twisting, I managed to convince an old university friend to use some seriously expensive pieces of kit to peek into the fine detail of the pride of J Allcock and Son’s product line. I sent several samples of our Ambiently-ground FKM crumb, and a competitor’s Cryogenically-ground FKM Crumb to my mate Rob Hooley, studying for a PhD in Materials Science at the University of Leeds, who was kind enough to put them through a Scanning Electron Microscope (SEM) and produce some fantastic pictures.


Picture 1 (Left) & 2 (Right): Cryogenically ground FKM 30’s Mesh and Ambient Ground FKM 40’s Mesh

These two pictures above show the difference in surface structure between cryogenically and ambient ground FKM crumb. The Cryogenic material has been frozen and shattered, thus the particle morphology appears much more angular and sharp compared to the torn material, with extremely rough edges due to the physical tearing of the rubber. The coarser material should bond better into a new FKM compound, due to the much larger surface area exposed to the fresh compound, and the possible exposed polymer chains due to the tearing of the material. As cryogenic freezing causes the rubber to break along micro-fissures or micro-tears, the surface would have fewer areas available for bonding.

Picture 3 (Left) & 4 (Right): Cryogenically ground FKM 72’s Mesh and Ambient Ground FKM 72’s Mesh

The pictures above again show the two types of ground FKM, but this time the smaller 72’s Mesh size. The size of the 2 grains is very similar, which is to be expected, but again the coarseness of the ambient ground material can still be seen. The scale of the peaks and troughs are not as extreme, but as this is a smaller grain, the increase in ‘bond-able’ surface area is not to be sniffed at. We at J Allcock and Sons believe (and have done many trials that prove our belief) that our ambient ground 72’s mesh FKM binds better than our 40’s mesh FKM crumb. 72’s mesh crumb can therefore be used at higher concentrations in newly made FKM compound, therefore saving you even more on compound cost.

Picture 5 (Left) and 6 (Right).  5 Shows Ambient ground FKM 72 mesh, using ‘LU’ settings, while 6 shows the same material, at the same resolution using ‘NM’ settings.

The ‘LU’ (seen at the base of this picture) indicates a technique that focuses on showing the topography of the sample using secondary electron imaging. SE imaging (SEI) involves electrons produced by ionisation induced by the incoming electron beam. These electrons are very low energy, and as such are very sensitive to the surface structure, this allows for the surface of the sample to be resolved in great detail, even showing the 3 dimensional structure of individual crumb.

Meanwhile, the ‘NM’ (again at the base of the picture) indicates Backscattered electron imaging (BSE), where electrons hit the sample with great energy, allowing them to penetrate the surface and interact with the bulk of the material. This results in the electrons bouncing around the material before being released. The energy they leave the material with is directly proportional to the mass of the atoms they interact with, much like how sound waves are absorbed by a carpeted floor, but bounce off a marble floor. Therefore, the light specks seen in the photo are heavier parts of the rubber compound, mainly Oxides of Magnesium, Calcium and Silicon (Thanks again to some further elemental analysis by Rob Hooley) as the heavier elements reflect more electrons and thus create a brighter image.

Pictures 5 and 6 therefore show the same sample of 72’s Mesh FKM using two types of imaging technique. Picture 5 (like the previous images) shows the surface contours of the FKM crumb, again showing the coarser nature of our material, which is ideal for binding into the compound matrix. Picture 6, however, reveals some of the components of the FKM compound as well as giving a different angle on the depth of some of the troughs and the quality of the FKM compound itself (nice even spread of a moderate amount of fillers can be seen in the crumb itself).

Picture 7 (Top left) and 8 (Top right). 7 shows cryogenically ground 72 Mesh FKM Crumb using LU (SEI) Settings, while 8 shows the same material under NM (BSE) Settings. Pictures 9 (bottom left) and picture 10 (bottom right) show ambient ground 72’s mesh FKM at the limits of the SEM’s resolution, again using ‘LU’ and ‘NM’ techniques respectively

These final images push the resolution of this electron microscope to its limits, with a scale of 10 microns seen in the bottom right hand corners of the lower two images. At such a large magnification, the difference in the surfaces of the crumb is more subtle. The main difference that can be seen would be the exposure of the filler. Picture 8 shows the filler underneath the surface, while picture 10 shows the exposed filler at the surface. We believe that the exposed filler will create an increasingly jagged surface, helping bonding into the compound at a smaller scale.

I hope you’ve enjoyed the pictures, and how microscopic differences in FKM crumb can have a large effect on the resultant compound.

Thanks again for the Fantastic Pictures, and some much needed advice on some of the more technical sections of this post to Rob Hooley, Here’s to our next pint in 2016!

Sehr gute zeit in Nürnberg!

After a busy few weeks, thanks to the tremendous interest generated by our stand at DKT, We’re happy to say that our venture to the European Technical Rubber Convention was a great success!

Highlighting the use of Rubber crumb and Granule in rubber compounds, without the loss of properties, Our unique FKM crumbing facility and the extremely small particle size we can generate was received with great interest. We were able to show, first hand, how fine our FKM powder can be made, thus increasing the amount you can add into your compounds and saving you considerable costs without any deterioration of FKM properties.

We’d like to extend a big thank you to everyone who can to visit our stand and we hope to continue providing technical knowledge and top quality products to all our clientele.

J. Allcock and Sons at DKT/IRC Nuremberg and Launch of the Multi-Language Website

We are happy to announce that we will be hosting a stand at the Deutsche Kautschuk-Tagung / IRC International Rubber Conference at the NuernbergMesse GmbH exhibition centre. We will be exhibiting Rubber Reclaim, Rubber Crumb and FKM Crumb, which promises to revolutionize the Fluoroelastomer Industry. With more and more compounders and moulders showing an interest and using our fine grades of FKM crumb, we would be happy to chat about the benefits of our product. Andrew Rushton, Managing Director of J. Allcock and Sons, and I will be manning the stand and hope to see you there to answer any questions our queries you may have.

In preparation for the conference, we have also had our website translated into French, German and Spanish. We hope this will make finding the correct product and information easier for our clients on the continent. If you find any grammatical or spelling errors on any page, please contact me and I will happily incorporate your suggestions to continually improve your experience of our website.

How to ‘Cure’ Some Moulding Issues

Rubber is of very little use until it has gone through the process of vulcanisation, where heat gives the energy needed for the long isoprene polymers to cross link, usually with sulphur side chains. Vulcanisation, often referred to in the rubber trade as ‘Curing’, turns rubber into the solid, elastic material that makes it so suited for the thousands of applications it is used for. As cured rubber is much stiffer than its pre-cured form, it has to be cured into the final form it is required to take, be it an O-ring, tubing or a coating on a fabric. Therefore, most rubber products are cured in the mould, which can be a classic mould press (with 2 heated plates pressing down on an amount of rubber to form the item with a small amount of flash) or injection moulding (where the mould is static and heated and the material is injected into it at pressure.

I’d like to take you through a couple of examples of experimentation made by our rubber consultant Norman Challinor that show how curing in the mould might not be as simple as you’d think.

Above is a photo of a test moulding using a piece of steel pipe as a mould (rubber piece is cylindrical around the rear) and 2 hot plates to cure from the top and bottom (as shown here). In this test a piece of wood was placed between the top hot plate and the rubber sample (as shown in picture) while the bottom hot plate was allowed to make full contact with the piece. After a set amount of time the hot plates were disengaged and the piece allowed to cool.

What can be seen is that the thermal insulation provided by the piece of wood prevented the top half of the sample from curing, which can be seen in the noticeable deformations made using a pen (while the cured lower half sprang back in place. The Steel pipe allowed the heat to conduct though the exterior (behind the sample in this image) but the wood retarded curing from the top of the piece due to restricting heat transfer. This shows the importance of the correct cure time for the thickness of a moulded object and for a manufacturer to think about where the heat sources are in their mould to ensure a complete cure of the product.

This second image shows an experiment to test a belief held by many in the rubber industry about Transfer Moulding.

Transfer moulding is like injection moulding, in that the rubber is ‘injected’ under the pressure of a hydraulic cylinder, but it is injected through several holes in the top plate of a heated mould (once the mould is closed) until the mould is filled.

It was believed that through the process of injection, the rubber compound would mix and form a homogenous piece of rubber. To test this, three separate sheets of rubber were placed in the hydraulic cylinder; in this case blue first, then white and finally red. As you can see, contrary to common belief, the rubber sheets failed to fully blend in the mould, leading to the patterning seen above. These separate layers may become weak points in the finished product, even though the product has cured evenly. It suggests extra care is needed at the moulding blank preparation stage, such as preheating to ensure an even heat throughout the rubber (which is known as the blank) before injection.

These two fun examples are great ways to show how it is important to test rubber technology theory to ensure success on the factory floor, even if what you are testing would seem like common sense. Such as the use of 2/3mm thick laboratory test pieces will not necessarily translate the correct cure times for the full sized product, due to the poor heat transfer of rubber itself.

Many thanks to Norman Challinor for the 2 sample pieces, and the stories and lessons behind them.

If you are having moulding issues, or think one of our products could help give you a more even, cheaper cured product please get in touch via our website, phone 0161 223 7181 or visit our stand at DKT2015/IRC 2015 12-352 Nuremburg 29th June to 2nd July!

Matt Darlington

Review of the Year – 2014 @ J Allcock and Sons

2014 at J Allcock and Sons Ltd.

It’s been another great year here at J Allcock and Sons. Rubber crumb and granule sales are up on last year, with an additional granulator to be installed next year and upgrading the line at our Wellington Rubber branch. FKM crumb production has increased 20% from last year and looks set to continue to increase into the New Year. In addition to our stringent particle size laboratory testing, we have recently instigated a quick pass/fail test during production, at short regular intervals. This will maintain the quality of our material that we’re known for.

Silicone sales are also up from last year, especially our Food Grade Silicone Emulsions. Of the small number of complaints to the company, most of them were due to poor housekeeping by the end user leading to silicone splitting (for tips on how to stop this, have a look at our previous blog post ‘A Splitting Headache’).

With this sustained increase in sales, we’re also looking into expanding our storage facilities, expanding our storage capacity by tens of tonnes.

Finally, we’ve welcomed 2 new members to the company. I joined just before Luke departed for a year in Australia, and Stephen has joined to learn the ropes controlling stock and purchases.

Looking to the New Year, we expect to continue our personalised service for our clients and welcome new clients from both the UK and the continent, thanks to our upcoming foreign language translations of our website. We’ll also be at DKT (Deutsche Kautschuk-Tagung) 2015 in Nuremburg in the summer to show our crumb and rubber reclaim to the European Rubber Community.

We’d like to say a big thank you to all our clients for continuing to choose us as there supplier, and the staff at J Allcock and Sons for a great year. We wish you all a merry Christmas and a happy 2015!

Matt Darlington

Types of Rubber – Pick-and-Mix

There are a near infinite variety of rubber compounds, with variety in mineral fillers, accelerators, curatives (and the type of cure), plasticizers, colour and of course the base rubber polymer. Rubber polymers come in two basic groups, natural and synthetic.

Natural rubber (NR), popularly known as Latex (when in the liquid form) or Natural Gum Rubber (once dried) is obtained mainly from the Hevea Brasiliensis Tree in South East Asia. Natural rubber consists of Cis-1,4-polyisoprene which can have masses as large as 1 million Daltons. Such large atomic structures, with plenty of double bonds, allows sulphur and heat to bond two double bonds of adjacent isoprene polymers with 3 or 4 sulphur atoms. This process is called vulcanisation, which was accidentally discovered by Charles Goodyear in 1839 using. Vulcanisation creates a network of bonds that changes the physical form of the Gum Rubber to the harder, elastic material that revolutionised the late 19th century world.

Initially sought by the Germans in the 1st World War, Synthetic Rubber was developed due to the Royal Navy’s Blockade causing a shortage of Natural Rubber. The first attempt at Artificial Rubber, Methyl Rubber, was of poor quality. Later attempts such as the Soviet use of Giant Dandelions to produce latex in WW2 weren’t much more successful. It wasn’t until the US Synthetic Rubber Programme developed Styrene Butadiene early in WW2 that a viable alternative to natural rubber became available, and the doorway to synthetic rubber polymers was opened.

There are now many types of rubber polymer, each tailored to the desired needs of the client. Below is a good rough outline to the characteristics of each rubber polymer, for example Acrylonitrile Butadiene Rubber is often used in oil seals and o-rings due to its excellent oil resistance:

Taken from:

We at J. Allcock and Sons are able to granulate NBR, SBR, EPDM, FKM and FFKM on site to any desired crumb mesh size, as long as the rubber is free of any textiles or metals. Crumb can be used as a filler in compounds, reduce the chance of trapped air causing lakeing during moulding or dusted onto rubber sheets to help the separation after cooling. Crumb is a great way to reduce compound cost without increasing the specific gravity of the compound (keeping volume costs down).

If you are interested in disposing of some of your cured rubber compound with us please get in touch via our website or phone us on 0161 223 7181.