BSS grade castor oil is a better grade than first special grade (FSG). It is usually paler in colour and has a lower acid value. The name refers to a British Standard Specification, which the trade still uses as a grade label.
In simple terms, FSG is the workhorse grade and BSS is the cleaner one. Which you need depends on what you make with it.
Where the name comes from
BSS stands for British Standard Specification. Castor oil was once traded against a British Standard, and the label stuck. Today, BSS grade is a commercial name. Each supplier has its own BSS specification sheet, and these are similar but not identical.
Do not assume that BSS on a quote means a particular current standard. Ask for the full specification and write the limits into your contract.
How BSS differs from FSG
The figures here are typical trade values for illustration. Real limits vary by supplier and contract.
- Acid value: BSS commonly has a lower maximum than FSG, often around half.
- Colour: BSS is paler, with a lower maximum on the Gardner or Lovibond scale.
- Moisture and impurities: limits are often tighter.
- Processing: BSS usually needs better seed, careful pressing and extra refining or bleaching.
- Natural properties: iodine value, hydroxyl value and saponification value are similar, since these come from the oil itself.
- Price: BSS normally trades at a premium to FSG because of the extra processing.
Who buys BSS
Buyers choose BSS when colour or acidity affects their product. Examples include paler derivatives, some coatings and inks, and personal care ingredients where a light colour helps. Many buyers of FSG convert the oil into derivatives where colour is removed later, so they do not need to pay for BSS.
Neither FSG nor BSS is a pharmaceutical grade. If you need oil to a pharmacopoeia, ask for that grade specifically, as covered in pharma-grade castor oil and USP or EP.
Choosing between them
The meaning of each test is explained in acid value, iodine value and colour for castor oil.
- Write down what your process needs: maximum colour, acid value and moisture.
- Ask two or three crushers for both grades with full specifications and recent results.
- Test both grades in your own process before deciding.
- Compare quotes on the same basis: grade, pack, Incoterm and payment terms. See how to compare castor oil quotes from different crushers.
- Check colour and acid value at loading, since both can drift with poor storage.
How we help
We get both FSG and BSS specifications from several Gujarat crushers, test samples at an NABL-accredited lab and compare quotes line by line. Before loading, we check the oil matches the grade you paid for. Ask for a free sourcing review.