Ask three suppliers for "white mineral oil, 100#", and you can receive three quotes for three legally different substances. One is a direct food additive, permitted on rice grain at 0.08 percent. One is a technical oil permitted only as a component of food-contact articles. The third is not permitted anywhere near food at all. All three are 100 cSt at 40 degC, all three are water-white, and two of them may print the same CAS number on the label. That gap is what this guide is about. The viscosity side - which N-number suits which application - is covered in our earlier white mineral oil grades guide, and the two articles are written as a pair.
Two numbers in one product name, and only one of them is about purity
A white mineral oil name carries a viscosity number and a grade. The number describes the fraction. The grade is a statement about how deeply that fraction was refined, and therefore about which regulator will let you use it.
White mineral oil is a mixture of saturated liquid hydrocarbons, essentially paraffinic and naphthenic, obtained from petroleum and then pushed through solvent extraction, dewaxing and hydrotreating until the aromatics, sulphur and nitrogen are essentially gone. The refining train is the product. Three process depths produce the three commercial grades:
- Industrial (technical) - refined for colour, volatility and oxidation stability. Aromatics are reduced but not eliminated, and no pharmacopoeia impurity guarantee is offered. Appropriate for textiles, rubber, plastics, leather, inks, candles and general lubrication.
- Food grade - the same train pushed further and then documented against a food-additive monograph, so that the residual polynuclear aromatic content is low enough to be controlled by ultraviolet absorbance rather than by colour alone.
- Cosmetic and pharmaceutical grade - the deepest cut, meeting a pharmacopoeia monograph (USP/NF Mineral Oil, Ph.Eur. Paraffinum Liquidum) that adds the readily carbonizable substances test and a DMSO-extraction absorbance limit.
The commercial trap runs in both directions. Paying a food-grade price for an oil that will only ever lubricate a knitting machine is waste; buying an industrial grade to save cost on a bakery release agent is a recall waiting to happen. And because the two grades look and flow identically, the only thing standing between the two outcomes is the paperwork.
Ultraviolet absorbance: the test that cannot be bleached away
Colour tells you almost nothing about refining depth, because a lightly refined oil can be filtered and clay-treated to water-white while keeping its aromatics. Ultraviolet absorbance cannot be faked in the same way. It is measured on a dimethyl sulphoxide extract of the oil, and DMSO pulls out exactly the polynuclear aromatic species that colour hides. That is why UV absorbance, not Saybolt colour, is the specification that separates a legal food oil from a decorative one.
The clearest illustration is that the two governing clauses of the same United States regulation define two different substances, both legally called white mineral oil, whose absorbance limits differ by a factor of forty:
| Route | Citation | Ultraviolet absorbance limit | What it permits |
|---|---|---|---|
| White mineral oil as a direct food additive | 21 CFR 172.878 | Must meet the UV absorbance specification of JAOAC 45, 66 (1962). Suppliers of food-grade oil normally publish a single limit of 0.1 absorbance per centimetre across 260-350 nm, and a Saybolt colour of +30 | Use in or on food itself: release agent, glaze, protective coating, dust suppressant, defoamer |
| Technical white mineral oil as a component of food-contact articles | 21 CFR 178.3620(b) | 280-289 nm max 4.0; 290-299 nm max 3.3; 300-329 nm max 2.3; 330-350 nm max 0.8 absorbance per cm; Saybolt colour 20 minimum | Adhesives, paper and paperboard coatings, filters, rubber articles, textiles and fibres, surface lubricants, and lubricants with incidental food contact |
Read those two rows together and the purchasing rule falls out: a technical white oil can be up to forty times more UV-absorbing than a food-grade oil and still be legally sold into food-contact articles. Both are "white mineral oil". Both may carry CAS 8042-47-5. If your specification stops at "white mineral oil, food contact" without naming the clause, you have not specified anything.
The same logic explains why CAS numbers are a poor proxy for grade. In our own portfolio the split runs along the pharmaceutical boundary rather than the food boundary: the cosmetic grades we stock carry CAS 8012-95-1, while the food-grade and industrial grades both carry CAS 8042-47-5. The CAS identifies the substance family; only the compliance dossier identifies the grade. Treat the two as independent and ask for both.
Four COA numbers that actually expose refining depth
Grade is often sold as a word. These four measurements turn it into a number you can audit.
- Carbon-type analysis, ASTM D2140. This reports the oil as aromatic carbon (CA), naphthenic carbon (CN) and paraffinic carbon (CP). A genuinely food-grade white oil is defined by CA approaching zero. A typical food-grade 100# oil published by a major producer reads CA 0, CN 25 to 35 and CP 65 to 75 percent. If a supplier cannot provide a carbon-type breakdown, you are buying colour, not refining depth.
- Aniline point, ASTM D611. The lowest temperature at which equal volumes of oil and aniline stay miscible. Aromatics dissolve aniline readily and depress the aniline point; paraffins do not. Higher is therefore better, and one number on a COA separates a deeply hydrotreated oil from a lightly extracted one. One published food-grade 100# specification reads a minimum of 120 degC and a typical of 127 degC.
- The purity trio: readily carbonizable substances, solid paraffin, and sulphide. These are the classic pharmacopoeia screens. Readily carbonizable substances is a concentrated sulphuric acid test that must leave the acid layer essentially uncoloured; solid paraffin is a 0 degC chill test that must remain clear; sulphide is a lead-acetate test for reactive sulphur. All three are pass-fail, and all three are cheap. They catch the oil that was filtered rather than refined.
- Viscosity-gravity constant, ASTM D2501. A one-line composition screen for buyers who hold only a density and a viscosity. For an oil above 5.5 mm2/s at 40 degC, VGC is calculated from density at 15 degC and kinematic viscosity at 40 degC. ASTM D2501 bands the result as paraffinic near 0.800, naphthenic around 0.850 to 0.899, and aromatic above 0.950. Placing the sample at density 0.867 g/mL and viscosity 105 mm2/s returns a VGC of about 0.79, squarely paraffinic - which is what a white oil should be. The value is insensitive to molecular weight, so it compares fairly across viscosity grades.
Two further numbers belong on the specification because they control handling rather than chemistry: the flash point, which governs the maximum processing temperature you can expose the oil to, and the distillation data, which is discussed below.
The Chinese monograph: five grades and a carbon-number ladder
China regulates food-additive white oil under GB 1886.215-2016, and the standard is unusually informative for a buyer because it does not stop at viscosity. It defines five grades and, alongside each, a minimum carbon number for the five percent distillation point - in effect a statement about how heavy and how clean the fraction must be.
| Property | Grade 1 | Grade 2 | Grade 3 | Grade 4 | Grade 5 |
|---|---|---|---|---|---|
| Kinematic viscosity at 100 degC, mm2/s | 2.0-3.0 | 3.0-7.0 | 7.0-8.5 | 8.5-11 | 11 minimum |
| Initial boiling point, degC, min | 230 | 230 | 230 | 230 | 350 |
| Carbon number at 5 percent distillation, min | 14 | 17 | 22 | 25 | 28 |
| Temperature at 5 percent distillation, degC, min | 235 | 287 | 356 | 391 | 422 |
| Average relative molecular mass, min | 250 | 300 | 400 | 480 | 500 |
| Saybolt colour, min | +30 | +30 | +30 | +30 | +30 |
Every grade carries the same limits on the safety-critical items, which is the point: polynuclear aromatic ultraviolet absorbance at 260-420 nm not more than 0.1 per centimetre, lead not more than 1.0 mg/kg, arsenic not more than 1.0 mg/kg, heavy metals as lead not more than 10 mg/kg, readily carbonizable substances and solid paraffin by test, and water-soluble acids or alkalis not detectable. Grade is therefore not a purity ranking in China - it is a fraction selection, and the purity floor is common to all five.
The pharmacopoeia route goes one step further and adds a low-carbon cut-off. The Chinese Pharmacopoeia monograph for white oil sets relative density at 0.830 to 0.860, kinematic viscosity at 40 degC not less than 12 mm2/s, a DMSO-extraction absorbance at 260-350 nm of not more than 0.10, a limit on sodium hydroxide consumption in the acidity test, no brown-black colour in the sulphide test, heavy metals not more than 10 mg/kg and arsenic within a 0.0002 percent limit. Note the carbon-number logic: the pharmacopoeia excludes the light end outright, because a heavy, narrow, low-aromatic fraction is inherently the safest one to put on skin or in a sterile setting.
Going into a food plant: H1, ISO 21469 and the 10 mg/kg rule
White mineral oil is also the base fluid behind a category of product that buyers often do not connect to it at all - food-grade lubricants for the machinery that makes and packs food. That route is governed by a different test entirely, and it is the one place where a lubricant can legally end up in food.
- The regulatory basis. Lubricants with incidental food contact are assessed against 21 CFR 178.3570. NSF H1 registration is the widely used proof of compliance, and it sets a maximum incidental contact level of 10 mg of lubricant per kilogram of food.
- The categories, which are not interchangeable. H1 is incidental food contact - gearboxes above the line, hydraulic systems near product, chain lubricants. H2 covers equipment where food contact is impossible. H3 and 3H are direct-contact release agents for grills, pans and other hard surfaces.
- H1 is a formulation statement, not a manufacturing one. It confirms the raw materials are approved. It says nothing about whether the plant that blended them also runs industrial-grade stock on the same line. ISO 21469 closes that gap by requiring segregated or validated-cleaned production, a HACCP-based risk assessment, controlled raw-material sourcing and an annual third-party audit. For serious processors, H1 plus ISO 21469 is the floor.
- Where the documentation is mandatory rather than nice to have. Brazil requires ISO 21469 certification for food-grade lubricants manufactured, imported or exported. The European Union has taken no regulatory action on mineral oil saturated and aromatic hydrocarbons in this category, but titanium dioxide is not accepted as a food additive there and is consequently excluded from lubricants intended for the European market. China's food hygiene law has no specific provision for food-grade lubricants, which means export-facing producers are the ones who must carry H1 or ISO 21469 documentation.
There is a practical thread back to the oil itself. A food-grade white mineral oil that is already compliant with FDA 21 CFR 172.878 and the EU plastics regulation for food-contact materials, listed as FCM substance number 95 in Regulation 10/2011, is the natural base for H1 lubricant formulations. That is why the food-grade grades in our range carry the same CAS as the industrial grades but a completely different set of documents in the folder.
Matching the grade to the job
With the purity question settled, the family separates cleanly by viscosity band and grade. The light industrial grades are carriers and surface oils; the mid range is the workhorse band; the heavy end is for films that must stay put.
- 5#, 7# and 10# industrial grade - textile auxiliary oils such as coning and knitting oils, agricultural spray oils, aerosols and precision instrument lubrication, where a low-viscosity, non-staining carrier that evaporates or wicks away cleanly is what the process needs.
- 15#, 20#, 26#, 32# and 36# industrial grade - the general-purpose band for machinery lubrication, plastic processing aids in PE, PS and PU production, rubber extender oils and leather care. This is where most industrial volume sits.
- 40#, 50#, 70# and 100# industrial grade - heavy machinery lubrication, rubber softening, sealing and caulking compounds and rust-preventive oils, chosen when the oil has to form a persistent film rather than drain away.
- 10#, 15#, 26#, 32#, 36# and 100# food grade - release and anti-stick agents, protective glazes and coatings for fruit, eggs and confectionery, grain dust control, defoamers and food-plant machinery lubrication. The viscosity choice usually follows the food being coated: a light grade for a thin, even glaze that must drain completely, a heavy grade where the film has to survive handling and abrasion.
- 22# cosmetic grade - the USP-style cut, where the article being made is the one that touches skin, and the specification shifts to the pharmacopoeia items rather than the food items.
The dose limits that come with the food route are specific and worth knowing before a customer asks. Under 21 CFR 172.878, white mineral oil is permitted at not more than 0.15 percent of bakery products as a release agent and lubricant, 0.2 percent of confectionery as a release, sealing and polishing agent, 0.3 percent in moulding starch, 0.25 percent in sorbic acid as an antidusting agent, 0.1 percent of egg white solids, 0.02 percent of dehydrated fruits and vegetables, 0.095 percent of frozen meat as a component of hot-melt coating, 0.6 percent of capsules and tablets, and 0.02 percent by weight of wheat, corn, soybean, barley, rice, rye, oats and sorghum as a dust control agent. Rice dust control is singled out for an ISO 100 viscosity oil, which is precisely our 100# food grade, at not more than 0.08 percent of the grain.
The goods-in checklist
For a food-grade or cosmetic purchase, the following items should be on the certificate of analysis rather than promised in an email. Ask for them once and the supplier base sorts itself out.
| Item | Expect | What a failure tells you |
|---|---|---|
| UV absorbance, 260-350 nm, DMSO extract | Not more than 0.10 per cm for food and cosmetic grade; a technical oil for food-contact articles may be far higher and is the wrong material for direct contact | The oil was bleached rather than hydrotreated, or is a technical grade being sold as food grade |
| Carbon-type, ASTM D2140 | CA at or near zero, CP typically 65 to 75 percent | Light refining; expect odour, colour instability and a UV absorbance that will not hold |
| Aniline point, ASTM D611 | 120 degC or higher for a heavy food-grade oil | Residual aromatics, and a good reason to demand the carbon-type analysis |
| Saybolt colour, ASTM D156 | +30 for food and cosmetic grade; 20 is the floor for technical white oil under 178.3620 | Feedstock quality or a filtration problem rather than a refining problem |
| Readily carbonizable substances, solid paraffin | Pass | The single fastest way to detect a filtered oil posing as a refined one |
| Heavy metals and arsenic | Lead not more than 1.0 mg/kg, arsenic not more than 1.0 mg/kg, heavy metals as lead not more than 10 mg/kg | Catalyst residue or recycled feedstock |
| Flash point and distillation data | Flash point appropriate to the viscosity grade, and a five percent distillation carbon number matching the declared grade | Light ends present; the oil will volatilise in the oven or the extruder |
| Regulatory statement | Named clause, not a category: 21 CFR 172.878 for direct food use, 178.3620 for food-contact articles, GB 1886.215-2016, Regulation 10/2011 FCM 95, or H1 with ISO 21469 for lubrication | "Food grade" with no citation is not a specification |
Two related articles are worth reading alongside this one: the viscosity-number guide for the application mapping, and our guide to beeswax, trihydroxystearin and petrolatum, which covers the semi-solid end of the same petroleum hydrocarbon family and the pharmacopoeia structure it shares with these oils.
Tell us the application, whether the contact is direct or incidental, and the market you are selling into, and we will confirm the viscosity grade, the purity grade and the documentation package before you place the order.