TOFA is not grown and harvested. In kraft pulping the resinous wood extractives collect in black liquor as a soap, are acidulated into crude tall oil (CTO), and the CTO then goes to fractional distillation. Distillation splits CTO into a fatty acid fraction (TOFA), a rosin acid fraction, an intermediate distillate and pitch.
What raw material and what process does TOFA come from?
Tall oil fatty acid comes from a different origin than vegetable fatty acids: not from an oilseed grown inside the food chain, but from a side stream of pulp production. In the kraft (sulfate) pulping process, cooking the wood chips releases the cellulose fibres while the resinous extractives of the tree (fatty acids, rosin acids, sterols and other neutral matter) pass into the cooking liquor.
That is why TOFA availability tracks pulp output rather than an agricultural harvest. Because the whole family derives from the same feed stream, CTO and its derivatives share a chemical identity: in the KORKİMYA portfolio both softwood and hardwood CTO, plus all three DTO grades, are described under CAS 8002-26-4. The fatty acid side of the distillation, TOFA, carries CAS 61790-12-3.
How does the kraft pulping process yield crude tall oil?
It helps to read the process as a three-stage separation chain, where each stage decides how cleanly the next one can run:
- Cooking: wood chips are cooked with an alkaline kraft liquor; the fibre separates while the extractives are converted into salts (soap) that remain in the black liquor.
- Soap skimming: as the black liquor is concentrated, solubility drops and the soap rises to the surface, where it is skimmed off. On the same process line the condensed volatile terpene fraction is recovered as a separate product, crude sulfate turpentine (CST).
- Acidulation: the collected soap is treated with acid to convert it back into free acids; once the aqueous phase separates, crude tall oil (CTO) remains.
What comes out at this point is not yet a fatty acid. Softwood CTO is described in the product data as a "complex blend (rosin acids, fatty acids, neutral matter)", appearing as a dark viscous liquid with a characteristic resinous odour. CTO is therefore a mixture of three component classes awaiting separation, and it does not substitute for TOFA in an alkyd resin or an ink formulation.
BİO BAZLI ÜRÜNLERSoftwood Crude Tall Oil (CTO)Softwood CTO is the feed of the distillation line: rosin acids (TUR-T 14), acid number (TUR-T 11), residual soap number (PCTM 13) and water content (Karl Fischer, PCTM 4C) are reported per lot. You can request a sample and the CoA.How does softwood CTO differ from hardwood CTO in production?
The wood species being cooked changes the feed of the distillation line, which is why the same process branches into two commercial routes. Softwood (coniferous) CTO is positioned explicitly in the product data as "distillation feedstock for tall oil fatty acids (TOFA), rosin and pitch". Hardwood CTO serves a different set of uses: collector and modifier in the froth flotation of oxidised ores and phosphates, anti-stripping binder modifier in asphalt, briquetting binder and mould release agent.
Its specification is built for that direct use rather than for distillation sharpness, so what gets reported are flow and handling parameters: acid value min 96 (ASTM D465 / ASTM D664), density at 15 °C 950-990 (ASTM D4052 / ASTM D1298), viscosity at 40 °C 100-200 (ASTM D445), flash point COC min 180 (ASTM D92), water content max 2% (ASTM D95) and pour point max 0 (ASTM D97).
Which products does fractional distillation split CTO into?
Distillation separates the components of CTO by volatility. Fatty acids are the lightest fraction, rosin acids are heavier, and the polymerised and neutral residue stays at the bottom. Where the cut is taken decides which commercial product comes out:
The table explains why the tall oil line is a product family rather than a single product. These items all come from the same CTO stream but they are not interchangeable: moving the cut changes both fatty acid purity and the residual rosin acid share, and each fraction goes to a different application group.
How does the sharpness of the cut show up in the specification?
Fractional separation is never ideal: some rosin acid and some neutral matter stay in the fatty acid fraction. The two upper limits in the TOFA specification measure exactly that carry-over, which makes them the measurable answer to how sharply the distillation was run:
- Rosin acid content (ASTM D1240): abietic-type rosin acids carried into the fatty acid fraction. Max 2% in TOFA 185, max 3% in TOFA 180.
- Unsaponifiables (ASTM D1065): neutral residue that does not enter the saponification reaction. Max 4% in TOFA 185, max 6% in TOFA 180.
- Acid value (ASTM D1980): the free acid density of the separated fatty acid fraction. Min 185 in TOFA 185, min 180 in TOFA 180.
- Appearance: the visible consequence of the cut. TOFA 185 is a light yellow to amber liquid, TOFA 180 an amber to dark amber liquid.
The same logic applies across the rest of the family. In the DTO grades fatty acids and rosin acids are deliberately left together, so the rosin acid limit is far higher: max 40% in the industrial grade and max 30% in the mid-high and premium grades. Premium DTO carries a tighter unsaponifiables limit of max 6% against max 7% in the other two DTO grades, and appears as a light amber, clear and bright liquid.
BİO BAZLI ÜRÜNLERTall Oil Fatty Acids 185 (TOFA)The grade that comes out of the sharpest cut: TOFA 185, with rosin acid max 2% and unsaponifiables max 4%, is routed to alkyd resin, printing ink and dimer acid lines. Request a sample, the CoA and a quote from the product page.How does knowing the process change your buying decision?
Understanding the process has three practical consequences. First: because TOFA supply sits on a pulp side stream, this family is structurally sourced away from the food chain if you want your fatty acid demand decoupled from edible feedstocks. Second: grade selection is not a brand preference but a choice of cut point; if your tolerance for rosin acid is low the sharper fraction is right, if it is high the more economical fraction is.
Third: an intermediate from the same process is sometimes the better match. If your formulation tolerates a defined level of rosin acid, TOFA Rich Distillate (acid number 178.5, total rosin acids 20.4) or one of the DTO grades may be a more accurate input than the pure fatty acid fraction. To run that comparison you need more than a product name from your supplier: ask for the per-lot certificate of analysis (CoA).
How is TOFA produced, in short?
In kraft pulping the resinous wood extractives collect in black liquor as a soap; that soap is skimmed and acidulated into crude tall oil (CTO), and the CTO goes to fractional distillation. The fatty acid fraction of that distillation is TOFA.
Are CTO and TOFA the same product?
No. CTO is the distillation feedstock and a mixture of rosin acids, fatty acids and neutral matter. TOFA is the fatty acid fraction separated out of it by distillation. CTO carries CAS 8002-26-4 and TOFA carries CAS 61790-12-3.
What else comes out of the distillation?
A rosin acid fraction, a fatty-acid-rich intermediate distillate (TOFA Rich Distillate), the DTO grades that contain fatty acids and rosin acids together, and pitch as the bottoms product (Ecophalt). At the cooking stage the volatile terpene fraction is also recovered as crude sulfate turpentine (CST).
What is the difference between softwood and hardwood CTO?
Softwood CTO is positioned as distillation feedstock for TOFA, rosin and pitch. Hardwood CTO goes to direct use instead: flotation collector and modifier, asphalt binder modifier, briquetting binder. Its specification reflects that, for example acid value min 96 and viscosity at 40 °C of 100-200.
Why does the rosin acid limit indicate distillation quality?
Rosin acids are unwanted carry-over into the fatty acid fraction. Measured by ASTM D1240, that share is limited to max 2% in TOFA 185 and max 3% in TOFA 180; the tighter the limit, the sharper the cut. The unsaponifiables limit (ASTM D1065, max 4% and max 6% respectively) is the second measure of the same question.
How does the production route affect supply security?
TOFA is not an agricultural product but a side stream of kraft pulping, so volume follows pulp production and is structurally decoupled from edible vegetable oil feedstocks. To settle the right grade for your own line, request a sample and a per-lot CoA from KORKİMYA.