Doultsons Ltd, dba Centralis Traders is a privately owned company with headquarters in Hong Kong.


Founded in 1991, the Group has been supplying Industrial Chemicals, Food Ingredients and Fertilisers for over 25 years.

Longman is the trademark under which the company distributes its products.  


Longman products encompass a broad spectrum of applications.


These include paints and coatings, paper and printing, glass manufacture, detergents, food and seasonings, and beverages.


Success of our brand has been built on the quality of our products, the strength of our relationships with clients and suppliers, and the loyalty of our staff.


Consistent quality, year on year, has earned us a host of prolific clients that include some of the foremost leaders in the industry.



We partner with suppliers that are aligned with our philosophical values.


We apply the same high standards we hold for ourselves, to the companies we work with.


Of the hundreds of manufacturers we come across, just a small fraction earn our Longman seal of approval.


Factors we consider include:


  • Quality                                  

  • Performance

  • Durability

  • Value

  • Safety

  • Integrity

  • Ecological Impact


Competitive pricing, consistent quality, and a fair code of ethics are what makes us stand out from the crowd.


Contact us to discover how we may add value to your business.



Longman Brand

"The preferred choice among manufacturers worldwide"


Industrial Chemicals










Food Ingredients

























Calcium Carbide
Phosphoric Acid
Sodium Sulphide
Sodium Saccharin
Citric Acid