Knowledge · Method
What was in this tote?
Send us a photo and we'll tell you
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Seven checks
How to read a container you know nothing about.
This is what our intake team does on every unit that arrives, in about four minutes.
- 01
Ask for the declaration first
Everything below is a cross-check, not a substitute. A prior-contents declaration from the original filler is the primary evidence. If a seller cannot produce one, the correct decision has already been made for you.
- 02
Look for the original label ghost
Even where labels have been removed, the adhesive shadow and the UV-bleaching pattern around it usually survive. Photograph it at a raking angle and the outline of a hazard diamond or a brand block often reappears.
- 03
Read the interior staining
Colour, height and pattern all say something. A uniform tide line at 90% says a liquid stored full and still. Streaked staining down one wall says something viscous that was pumped. Crystalline deposits say a saturated solution or a fertiliser.
- 04
Smell the outlet, not the lid
The valve body holds residue longer than anywhere else in the container. Crack it and smell there. Solvent, ammonia, sour dairy and petroleum are all unmistakable months later.
- 05
Check the gasket material
A Viton gasket is a strong tell. Nobody pays for Viton unless they were handling aromatics, hydrocarbons or chlorinated solvents. An EPDM gasket suggests aqueous chemistry — acids, bases, water-based product.
- 06
Look at the bottle wall itself
Permanent cloudiness or a slight amber cast is permeation, and it means an organic compound has migrated into the polymer. That container is industrial for the rest of its life whatever anyone tells you.
- 07
Read the plate for context
The packing group letter narrows it. A Y or X marking tells you it was built for regulated dangerous goods; a container marked Z was only ever approved for minor-danger material. The date tells you which era of product formulations you are dealing with.
Field guide
What the evidence usually means.
Indicative, not diagnostic. Use it to form a question for the seller, not to convince yourself you already have the answer.
| What you see or smell | Usually means | Reuse implication |
|---|---|---|
| Clear bottle, faint sweet solvent smell at the valve | Alcohols, glycols, IPA | Industrial only. Permeation likely |
| Amber cast to the wall, no visible residue | Aromatic or chlorinated solvent | Industrial permanently. Never food |
| Heavy dark streaking, sticky to touch | Molasses, syrup, edible oil | Often excellent — food history, just filthy |
| White crystalline deposits at the base | Saturated salt solution or liquid fertiliser | Washes out. Check for scale in the valve |
| Uniform pale film, chalky | Latex or water-based paint | Washes with effort. Industrial |
| Green or blue tint to residue | Copper-based ag chemistry or coolant | Industrial. Declare it — some are regulated |
| Sharp ammoniacal smell | Cleaning concentrate or fertiliser | Washes well. Ventilate before entry |
| Viton gasket fitted | Hydrocarbons, aromatics, oils | Strong indicator of solvent service |
| No smell, no stain, cloudy wall | Solvent, long dwell | The dangerous one. Looks perfect, is not |
Why appearance and risk are uncorrelated
The instinct everyone brings to a used container is that dirty is bad and clean is good. In this trade it is close to backwards.
A tote that held molasses looks disgusting — dark, sticky, streaked to the roof — and is completely benign. It washes out, it has a food history, and it is often the most valuable container on the pallet. A tote that held a chlorinated solvent for eight months looks pristine, because solvents leave nothing behind on the surface. What they leave is in the wall, and it will migrate back out into whatever goes in next for years.
This is why we grade on documentation first and appearance second, and why food-grade status is a claim about history rather than a claim about cleanliness.
Permeation, in one paragraph
HDPE is a semi-crystalline polymer with amorphous regions that many organic molecules can enter. Given time and concentration, a solvent does not merely wet the inside surface — it dissolves into the polymer matrix and distributes through the wall thickness. Removing the liquid does not remove what is in the wall; it simply reverses the concentration gradient, and the compound begins slowly diffusing back out. No wash cycle reaches it because it is not a surface phenomenon. This is the entire reason a chemical tote can never legitimately be sold as food grade.
What we do with unknowns
They go to quarantine, which sits deliberately in everyone's way between intake and the wash bays. From there, one of three things happens: the seller produces documentation and it rejoins the queue; it is downgraded to Grade C for static non-food use and priced accordingly; or, if there is any reason to suspect something we cannot handle, it goes back. We have never regretted sending a container back.
Can I just wash a tote and not worry about what was in it?
No. Washing removes surface residue and does nothing about permeation, which is the compound that has migrated into the polymer wall and will leach back out for years. This is the single most important thing to understand about used containers.
What if the seller says they don't know?
Walk away, or buy it as a Grade C for static non-food, non-transport use only, and price it accordingly. An unknown container has one legitimate future: ballast, containment, or something structural. Never water you drink, never soil you grow in, never regulated transport.
Does a clean-looking interior mean it's safe?
Absolutely not, and this is the trap. Many of the worst contaminants — solvents in particular — leave a container looking spotless. Meanwhile a tote that held molasses looks appalling and is completely harmless. Appearance and risk are close to uncorrelated.
Send us four photos and we'll read it for you.
Plate, interior with a flash, valve and the outside. We do this several hundred times a month and we're happy to do it for containers you didn't buy from us.
