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.


Straight to Print – DC 2418, The Post-Application Printable/Paintable Silicone Emulsion

One of the downsides of using Silicone oils or emulsions as a release agent is that the material you’ve released from the mould can’t be printed on or painted until the silicone oil has been cleaned off. The very nature of silicone oil, that it’s a non-poler, slippy polymer, means that any paint or ink wouldn’t penetrate the layer of oil, or would mix in with it. DC 2418 emulsion not only allows printing and painting of post-moulded products, thanks to Ethylated Silicone oil (and some other ingredients) but as it’s an emulsion, it’s as easy to use as traditional Silicone Emulsions.

If you’re interested in the specific properties of DC 2418, and it’s possible uses, please get in touch.

Mastering the Future of Siloxanes – Silicone Oil Masterbatches

Polydimethylsiloxane (or Silicone Oil) has been a leading mould release agent since the 1950’s. Its inert chemical nature, extreme heat resistance and total lack of harmful contents have made it the obvious choice for many. However, as plastics rose to predominance in the moulded goods sector, the use of silicone oils began to decline. Difficulty of printing on treated surfaces and the occasional slip-inducing spillage put some off using Silicone oils in favour of other mould release agents. Though the issue of printing can be solved using specialist emulsions, many manufacturers wanted to remove liquids from their production processes.

After a long development process, Dow Corning produced a method of binding Ultra-High Molecular Weight Siloxane Polymers (usually with a viscosity of millions of centistokes) into small pellets of plastic, resulting in Siloxane Master Batches (Siloxane MBs). These enabled in built Silicone Oil lubrication to be added in highly controlled doses into any plastic desired, with the use of specific solid carriers (PET, PP, polystyrene, etc). Doses as low as 1% added along with any other master batches being used (eg colour) to give the desired slip needed in a moulded product, with the added bonus of the longevity of lubrication granted by such long chain Siloxane polymers.

Siloxane MBs have the potential to be used in a huge variety of roles, in fact any that require the lubrication of plastic goods. They can be used at all stages of manufacture, be it during production, such as its use in the manufacture of plastic fibres, or to help end use such as aiding the fitting of plastic piping together.

We currently sell Dow Corning Siloxane Master Batches and are happy to help with any technical issues or trials you wish to persue. We also supply a specialist Silicone Emulsion that allows printing and painting on treated surfaces. If you have any questions or are interested in these products, please contact us through our website and we will be happy to assist.

Matt Darlington

Silicone Emulsions – A Splitting Headache

Silicone Emulsions – A Splitting Headache

Although it was mentioned in our most recent Silicones blog (06/03/14). We here at J Allcock & Sons thought it would be a good idea to add a post about the problem of Silicone emulsions splitting.

Silicone Emulsions are basically Silicone oil, water and an emulsifier. The Silicone oil does the job (usually lubrication), the water carries the oil and allows for easy dilution of the oil and the emulsifier binds the two together.

However, problems can arise in emulsions, the large array of splitting possiblilties are shown perfectly in the diagram below:

Taken from:

Though there are many technical terms, the origin of all these kinds of splitting are the same. Like milk, Silicone emulsions can ‘go off’ if left in a hot, moist environment. Like milk, Bacteria and fungi can grow that feed on the emulsifier and cause the separation of an emulsion, leading to a ‘lumpy’ consistency.


There are a few precautionary measures that can be taken to ensure your Silicone Emulsion doesn’t split;

  • Store the container in a cool, dry area
  • Do not store diluted material for long periods of time
  • Regularly wash out dilution vessels to stop bacteria/fungi carrying over into fresh batches
  • Use Allcosil Stabiliser to increase the lifespan of your Silicone Emulsion

We hope this helps answer any questions on silicone splitting you may have. If you’d like more info please get in contact via the website or by calling myself on 0161 223 7181.

Matt Darlington

Silicone Oils, Emulsions & Antifoams

Silicone Oils, Emulsions & Antifoams

J Allcock & Sons have been selling silicones to a wide range of industries since the 1970’s. Our last silicones post on 07/11/12 missed out one of our main silicone products and as I have recently started here, I thought it would be a good first topic to write on, with the help of our technical wiz, Norman.

We’d like to go over our 3 main products in the silicone range; Silicone Oils, Silicone Emulsions and Silicone Antifoams. We’ll outline some basic information, uses and grades that J Allcock & Sons offer.

Silicone Oils

Basic Info

Silicone oils are the sensible place to start as all our silicone products are based around silicone oil. silicone oil has many names; some call it Silicone Fluid, Americans tend to call it Dimethicone, while we call it Allcosil 200.

The Scientific name is Polydimethylsiloxane, which is also the most descriptive as the chemistry minded among you can see ‘Poly’ for many, ‘Dimethyl’ for two methyl groups (CH3) and ‘Siloxane’ for Silicone and Oxygen. The resulting structure resembling this:

Taken from:


Thanks to its methyl groups and Si-O backbone, silicone oil is one of the most inert oils around. It’s a water repellent, dielectric, temperature resistant, semi-Newtonian and non-toxic lubricant, which lends itself to uses in the moulding, food packaging, automotive and cosmetics industries.

Our Range

Silicone oils come in a wide array of viscosities, which are dependent on the length of the polymer (the longer the polymer, the more viscose the oil). The different viscosities enable silicone oil to perfectly meet desired needs; Allcosil 200/20 has been used for laboratory heat baths, while Allcosil 200/12,500 can be used as a hydraulic fluid. Silicone oil can come in industrial grade, food grade and cosmetic grade. The common viscosities of Allcosil 200 are 20, 100, 200, 350, 1000, 12,500, and 60,000 (the full range and further information can be seen in our previous blog)

Silicone Emulsions

Basic Info

Silicone emulsions contain 3 components silicone oil, emulsifier and water. The silicone oil provides the desired characteristic, most often lubrication. The emulsifier binds the silicone oil with the third component, water, so that the oil is suspended in solution and can be diluted down easily. The emulsifier-bound oil forms microscopic droplets of a uniform size in the water, which thanks to Brownian motion are kept at roughly an even distance apart.

As long as the droplets remain in this suspension the emulsion will be in good working order, however if the droplets are allowed to rise to the top of the solution (‘Creaming’) form into small clusters (‘Flocculation’) combine into large droplets (‘Coalescence’) or form a continuous layer on the solution’s surface (‘Breaking’) the emulsion will cease to work (see below for a good schematic).

If any of these problems occur, we at J. Allcock & Sons will be able to help solve the problem. We have our own stabilizing agent (Allcosil Stabilizer) that can resolve most emulsion separation issues.

Taken from:


Silicone emulsions are mainly used as a lubricant. One such use is as an anti-nesting agent for the thermoplastic container industry, another as a mould release agent in the rubber industry. Wherever a small amount of silicone oil is needed (usually in ppm) silicone emulsion is the best product.

Our Range

We have a wide range of silicone emulsions available. Allcosil 35 is a 35% silicone oil emulsion suitable for industrial use, while Allcosil 356 and Allcosil 435FG are food grade 35% emulsions. A 60% Silicone oil emulsion suitable for industrial use (Allcosil 60B) may be useful if a smaller dilution is required. We also supply high viscosity oil emulsions, if you wish to use higher centistoke oil in your emulsion (Other emulsions are available) Again our previous blog post has more information on emulsions.

Silicone Antifoam

Basic Info

Antifoams use the intrinsic property of silicone oil to lower water surface tension to pop bubbles and eliminate foam (see below) Silica particles are also present to help pop bubbles through physical piercing.

Taken From:


Silicone antifoams can be used wherever foams form and need to be removed. When solutions are pumped through a high pressure system, soaps are used, or froth is generated by chemical or biological action e.g. in sewage treatment, antifoam can be used to totally remove foam from the solution.

Our Range

As only tiny amounts of silicone are needed for the antifoam effect, J. Allcock & Sons provide two main products, A.011 and Allcosil 30G Antifoam, 10% and 30% silicone based antifoams respectively. We also provide food grade antifoams for the food industry, both 10% and 30% available.

I hope this helps in any Silicone-based queries you may have. If you’d like more information or are interested in any of our products please call myself on +44 (0)161 223 7181

Matt Darlington

Silicone Oil (Polydimethylsiloxane) & Emulsion

J. Allcock & Sons we have been supplying silicone products (silicone oil, silicone emulsion, silicone grease, and more) to many industries since the 1970′s. Therefore we have decided to explain some of the chemistry behind the two most popular; silicone oil and silicone emulsion. We hope you find it useful.

Silicone Oil

First of all, silicone oil has many different names; silicone fluid, polydimethylsiloxane, dimethicone, dimethylpolysiloxane, dimethyl siloxane, PDMS. J. Allcock & Sons have branded our silicone oil Allcosil 200 (which only adds further to the confusion!)

Technically, we believe that polydimethylsiloxane best describes the oil. Poly (Latin for many), dimethyl (two methyl (CH3) group) siloxane (Silicone and Oxygen).

The chemical structure of polydimethylsiloxane is:

n= number dimethylsiloxane units.

Buyers of polydimethylsiloxane will be aware that it is available in a number of different viscosities. The most common being; 100cSt(centistoke), 350cSt and 1000cSt. The number of dimethylsiloxane units depicts the size of the polymer chain which determines the viscosity. The smaller the polymer chain the lower the viscosity (e.g. 100 cSt) , the bigger the polymer chain the higher the viscosity (e.g.1000cSt).

Our one product in the Allcosil 200 range that is slightly different is our lowest viscosity Allcosil 200; 0.65cSt. Allcosil 200/0.65 has only two units, this means that it is not a polymer, but a dimer. The dimer is hexamethyldisiloxane.

The chemical structure of hexamethyldisiloxane is:


It is clear that when you compare it to the polydimethylsiloxane structure that the dimer is very similar to polydimethysiloxane.

The polymer chain length also has an effect on other properties of the oil.

Viscosity, cSt Flashpoint, °C COC Freezing Point,°C Specific Gravity, @ 25°C Surface Tension, mN/m Refractive Index, @ 25°C
0.65 -4 -67 0.760 15.9 1,375
1 40 -85 0.816 17.4 1,382
2 48 -90 0.830 18.1 1,387
3 62 -100 0.900 18.9 1,392
5 136 -100 0.910 19.7 1,397
10 162 -65 0.930 20.1 1,399
20 230 -60 0.950 20.6 1,400
50 280 -55 0.959 20.7 1,402
100 >300 -55 0.965 20.9 1,403
200 >300 -50 0.970 21.0 1,403
300 >300 -50 0.970 21.1 1,403
350 >300 -50 0.970 21.1 1,403
500 >300 -50 0.970 21.1 1,403
1000 >300 -50 0.970 21.2 1,403
5000 >300 -50 0.975 21.4 1,403
10000 >300 -50 0.975 21.5 1,403
12500 >300 -50 0.975 21.5 1,403
30000 >300 -50 0.975 21.5 1,403
60000 >320 -50 0.975 21.5 1,403
100000 >300 -50 0.976 21.5 1,404
300000 >300 -45 0.976 21.5 1,404
1000000 >300 -40 0.976 21.5 1,404

(1000000 cSt, longest polymer chain.)

It is clear from the table showing properties, that after 50cSt, the polymer chain length becomes less important in effecting the properties.

According to the FDA Regulation 21 CFR, certain viscosities are food grade. For more information, please contact us.

Silicone Oils have many uses due to their lubrication, dielectric and water repellent properties.

Silicone Emulsion

Silicone Emulsion contains 3 ingredients; polydimethylsiloxane, emulsifier & water.

The key ingredient is the emulsifier which encapsulates the polydimethylsiloxane oil and holds it in suspension.

A typical emulsifier used in making silicone emulsions is ethoxylated glycol ethers. These emulsifiers have a hydrophobic (dislikes water) and hydrophilic (likes water) part to their structure. The hydrophobic faces the polydimethylsiloxane and the hydrophillic faces the water. This creates a barrier between the water and the polydimethylsiloxane.

Here is a really good picture i found on google. A surfactant (Surface active agent) is just a type of emulsifier.

Unfortunately emulsifiers, due to their chemical make-up, are vulnerable to bacteria. Bacteria can digest certain emulsifiers causing the polydimethylsiloxane to float to the top or disrupt the pH enough for non-digestible emulsifiers to split from the oil. This is called splitting. Splitting in an emulsion can be seen and smelt. The smell comes from the bacterial growth, it usually smells like sour milk.

Emulsions are a key mould realease/lubricant and antifoams for many industries.Our biggest selling emulsion is Allcosil 435 FG, this is sold to the food packaging industry. It is food grade and kosher certified.


If you have any questions, please feel free to leave a comment.