A practical guide to solid-grade polyethylene glycol, why viscosity is how you verify the grade, and how PEG 3350, 6000, and 8000 differ, from a US-based distributor.
Polyethylene glycol (PEG, CAS 25322-68-3) is a water-soluble polymer sold by nominal molecular weight. The solid grades — PEG 3350, 6000, and 8000 — are waxy white flakes or powders used as thickeners, lubricants, binders, and excipients. The number is the approximate molecular weight, and viscosity is what actually distinguishes one grade from another. Stratus Chemical supplies these grades in bags and drums across the United States.
| Property | Value |
|---|---|
| Chemical name | Polyethylene glycol |
| Synonyms | PEG, polyoxyethylene, polyethylene oxide, macrogol |
| CAS number | 25322-68-3 |
| Molecular formula | H(OCH2CH2)nOH |
| Appearance | White waxy flake or powder |
| Water solubility | Freely soluble |
| Grades supplied | PEG 3350, 6000, 8000 (technical / NF, subject to availability) |
| Packaging | Bags, drums |
| Documentation | COA & SDS provided on request |
The figures below are representative of industrial grade material. They are indicative rather than guaranteed: specifications vary by source and by lot, and the certificate of analysis for your material governs.
| Determination | Specification |
|---|---|
| pH (5% aqueous) | 4.5 – 7.5 |
| Color, alpha (25% aqueous) | 20 max |
| Viscosity at 210 °F | 85.0 – 115 |
| Determination | Specification |
|---|---|
| pH (5% aqueous) | 4.5 – 7.5 |
| Color, alpha (25% aqueous) | 20 max |
| Viscosity at 210 °F | 700 – 900 |
PEG 6000 sits between these two. Ask us for the current specification for that grade rather than interpolating from the tables.
Polyethylene glycol is a polymer of ethylene oxide, and the number after the name is its approximate average molecular weight. That single figure governs almost everything about how the material behaves.
Below roughly 600 the polymer is a clear liquid. Above about 1000 it becomes a waxy solid, and the higher the molecular weight the harder, higher-melting, and more viscous it becomes in solution. PEG 3350, 6000, and 8000 are all solids, supplied as flake or powder.
What does not change across the range is the chemistry. Every grade is freely soluble in water, non-volatile, chemically inert toward most materials, and low in toxicity. Choosing a grade is a physical decision, not a chemical one.
This is the practical point worth taking from the specification table, and it is why the viscosity line matters more than it looks.
PEG 3350 and PEG 8000 have identical pH and colour limits. Side by side as white flake they are hard to tell apart. But viscosity at 210 °F runs 85 to 115 for the 3350 grade and 700 to 900 for the 8000 — roughly an eightfold difference.
That gap is the fingerprint. If a delivery is labelled PEG 8000 and the certificate shows viscosity near 100, you have received the wrong grade, and no other line on the certificate would have told you. In a formulation built around a target viscosity, substituting one for the other changes the product completely.
Solid PEG grades thicken and stabilise creams, lotions, and cleansing bars, add body and slip, and serve as the base for stick and solid formats. They are also used as humectants and as carriers for actives.
PEG is a standard excipient, used as a tablet binder and lubricant, in film coatings, and as an ointment and suppository base. NF grade material is required for these uses, so specify it explicitly.
PEG works as a lubricant and mould release, a dispersant and binder in ceramics and metal powder processing, an antistatic agent in plastics, and a plasticiser. Its water solubility is often the deciding property: a PEG binder can simply be washed out in a later stage.
Used as a softener and lubricant in textile processing, a plasticiser in paper coatings, and a levelling and flow aid in water-based coating systems.
| Grade | How it behaves | Where it fits |
|---|---|---|
| PEG 3350 | Softer solid, lower solution viscosity, dissolves readily | Formulations needing solubility and moderate body without heavy thickening |
| PEG 6000 | Intermediate hardness and viscosity | General-purpose binder and thickener; the usual middle option |
| PEG 8000 | Hardest of the three, highest viscosity, highest melting range | Where structure, hardness, or strong viscosity build is the objective |
How to choose: start from the physical property you need. If the requirement is thickening or structure, move up in molecular weight. If it is fast dissolution or a softer feel, move down. Because the chemistry does not change across the range, grades can often be blended to hit a target between them, which is worth considering before paying for a custom specification.
Store PEG dry in closed original packaging in a cool place, off damp floors. The material is hygroscopic and will pick up moisture from humid air, which causes flake to clump and complicates handling and metering.
Keep it below its melting range in storage. Solid grades that soften and re-solidify form a fused mass that is difficult to break out of a bag or drum.
PEG is stable and presents a low hazard in normal handling. Molten PEG causes thermal burns, and spilled material is extremely slippery underfoot. Follow the Safety Data Sheet for the specific grade.
Polyethylene glycol is used as a thickener, lubricant, binder, and excipient. Solid grades such as PEG 3350, 6000, and 8000 appear in creams, lotions, and cleansing bars in personal care; as tablet binders, lubricants, and ointment bases in pharmaceutical manufacture; and industrially as mould releases, dispersants, antistatic agents, and plasticisers. Stratus Chemical supplies these grades in bags and drums across the United States.
It is the approximate average molecular weight of the polymer. PEG 3350 has an average molecular weight near 3350 and PEG 8000 near 8000. The number is the single most important thing about the grade, because it determines whether the material is a liquid or a solid, how hard it is, its melting range, and how much viscosity it builds in solution. The underlying chemistry is the same across the range.
Molecular weight, and therefore physical behaviour. Both share the same pH and colour specifications, but viscosity at 210 degrees Fahrenheit runs roughly 85 to 115 for PEG 3350 against 700 to 900 for PEG 8000. PEG 8000 is harder, melts higher, and builds far more viscosity; PEG 3350 is softer and dissolves more readily. They are not interchangeable in a formulation built around viscosity.
Check the viscosity figure on the certificate of analysis. Solid PEG grades look nearly identical as white flake or powder, and pH and colour limits are the same across grades, so those lines will not distinguish them. Viscosity differs by roughly eight times between PEG 3350 and PEG 8000, which makes it the practical fingerprint for verifying the grade you were shipped.
NF grade is available subject to availability, and it should be specified explicitly at the enquiry stage if your application requires it. Pharmaceutical, nutraceutical, and many personal care applications call for compendial grade material, which is a different product from technical grade and is documented differently. Tell us the grade and the documentation you need when you request a quote.
Store PEG dry in closed original packaging in a cool place, off damp floors. It is hygroscopic and will take up moisture from humid air, causing flake to clump. Keep it below its melting range, since material that softens and re-solidifies fuses into a mass that is difficult to remove from the bag or drum. Spilled PEG is very slippery underfoot.
Stratus Chemical supplies polyethylene glycol in bags and drums, in PEG 3350, 6000, and 8000 grades, with a certificate of analysis provided for each shipment. Tell us the grade, the specification you are working to, and the volume, and we will confirm pricing and availability within one business day.
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