Glass capillary Viscometer Manufacturing and Calibration

WE DO THINGS our way

We navigate technology advances in our field with a flexible mindset. As an independent operator in Glass Capillary Viscosity, we answer only to our customers. Using our experience and modern technology, we do our best to continuously improve our offering. We offer classic precision quality performance in an automated package suitable for the expediency requirements of the 21st Century.

How to measure kinematic viscosity in a glass capillary viscometer


Helping process industry customers certify PET, PA, PULP, MCC, PVC & HA

Process plants across the world trust their PSL Rheotek viscometer systems for daily testing of product stream. Using an automated glass capillary viscometer system, they determine intrinsic viscosity, K-value, degree of polymerisation, – all in full compliance with international test methods.

Test results form part of legal contracts for bulk trading of commodities deep in the cogs of the manufacturing process.

PSL Rheotek automated viscometer systems first appeared back in the late 1990’s in response to industry requirements for automation. Then and now, Poulten Selfe & Lee Limited, was already a world player in the field of capillary viscometry. With a manufacturing and calibration operation covering the standard viscometer tubes as per specifications of ASTM, DIN, ISO and other standards organisations, the move into automation was organic.

PSL was originally established in 1850 and supplied a wide range of laboratory equipment. Scientific glassblowing was always at the heart of the manufacturing process. In more recent history, the glassblowing expertise and experience has been exclusively focused on capillary viscometers. We make beautiful viscometers with excellent flow properties.

Currently, the PSL Rheotek range of automated viscometer systems are on Generation 3. It is our mission to assist manufacturers to employ scientific method in their operation.

A special area of interest for us is to work with manufacturers in emerging markets. In addition to a very comprehensive base of installations in North America and Western Europe, we are also active in Vietnam, Pakistan, Indonesia, South Africa and Angola.


years of experience


viscometers sold


countries served


satisfied clients


Making Polymer Solution Viscosity easier

Recyclers, compounders, petrochemical industries, pulp mills and pharmaceutical manufacturers all need to run continuous viscosity testing on product stream. The certificate of Analysis is a key document for process control. The certificate of analysis is also a key document for product sale. At PSL Rheotek we focus on designing the right configuration of instrumentation for each client. Our mission is to help manufacturers obtain the right data in the easiest and most convenient way using glass capillary viscosity measurements.

We see ourselves as a small cog in the big machine of process industry. Our technology assists process industry with optimizing their process. This helps them to limit their waste and send the right product into the next stage of manufacturing.

PSL Rheotek glass capillary viscometers


What you see is what you get

The heart of what our organization stands for WYSIWYG – What you see is what you get. We believe in transparency and open dialogue. As a small operator serving large corporations with critical measurement technology in glass capillary viscosity, we benefit from being nimble and technologically aware. We are the dependable partner for the long haul. Our client relationships rest on dialogue and experience.

Honesty, integrity and attention to detail. We want to get it right for the client. Our day-to-day operations are carried out as a team effort. Respect for each other, politeness and helpfulness guide our work and our attitudes.


If we cannot measure your samples, we will not sell you the instrument.


Our staff hail from multiple countries representing Europe, the United States & Asia. We serve clients all over the world.


Behaving with decency helps build the mileage on the long road of the client relationship.


A smile goes a long way on grey day. We encourage a safe, friendly environment with space for humour.


Respect is a key pillar in our code of conduct.


Custom products for unique requirements

We offer the most reliable results in the highest resolution. It all begins at the bench in our world class glassblowing workshop. Our knowledge and experience walk hand in hand in partnership with our customers.


Development of automated viscometer systems, including the design of embedded systems, robotics and software.


Glassblowing of high precision viscometer tubes.


Calibration of viscometer tubes, blending and calibration of viscosity reference standards, calibration of digital thermometers.


Meet the leadership

Stephen Gosling

Stephen Gosling

Managing Director

Where other people see limitations, Stephen Gosling sees a challenge. He is a visionary entrepreneur, who leads our diverse team of specialists. His solid expertise in all business matters ensures that commercial considerations always walk hand in hand with high flying visions.

Sophie Gosling

Sophie Gosling

Commercial Director

When you are unsure about your viscosity question, there is every chance, that Sophie will be able to work it out. As the commercial anchor for project sales world-wide, she is the go-to person for dealers and clients from around the world.

David Blair

David Blair

Operational Manager

Friendly, firm and extremely competent. David Blair holds all the strings together ensuring that manufacturing, calibration services and shipping all operate in unison, also a Master Glassblower, he has deep product knowledge under his skin.