Knowledge · G-04
Food grade
vs industrial.
Short answer
- Verify with the prior-contents affidavit — no affidavit, no claim
- Food lines run hot water only; caustic disqualifies
- Odour inside = permeation = disqualified regardless of paperwork
- Industrial grade is genuinely fine for non-food duty
Check a grade with us
Side by side
What actually differs
| Food grade | Industrial (reconditioned) | |
|---|---|---|
| Bottle resin | Virgin HDPE, FDA 21 CFR 177.1520 | Usually the same resin — compliance is not the differentiator |
| Prior contents | Food-contact only, documented | Non-food; disclosed in writing |
| Documentation required | Affidavit from the original filler | Prior-contents disclosure |
| Wash chemistry | Hot water only, 82 °C | Caustic, hot water or solvent as matched |
| Wash line | Physically separated bay, own lances and drain | General wash bays |
| Base type | Plastic or composite, never bare wood | Usually steel |
| Gasket | Food-grade EPDM or platinum-cure silicone | EPDM or Viton as matched to product |
| Interior odour tolerance | Zero — odour is disqualifying | Faint residual odour acceptable |
| Price band, 275 gal | $185 – $340 | $120 – $225 |
| Can be regraded downward | Yes, to industrial | Yes, to rinsed or as-is |
| Can be regraded upward | N/A | Never |
Note the first row. The resin is frequently identical — most IBC bottles are moulded from compliant virgin HDPE regardless of intended service. What you are paying the premium for is the documented history and the segregated wash line, which are harder to obtain than the plastic.
The science
Why permeation makes this permanent
This is the one paragraph that resolves most arguments in this trade, so it is worth being precise.
High-density polyethylene is a semi-crystalline polymer with amorphous regions between the crystalline domains. Small organic molecules — solvents, fragrance compounds, some surfactants, many aromatics — diffuse into those amorphous regions over time. The driving force is a concentration gradient, and the process takes days to weeks depending on temperature, concentration and the molecule’s size and polarity.
Once absorbed, those molecules are inside the wall rather than on it. A hot caustic wash acts on the surface: it removes the residue layer and any film, and it does essentially nothing to the absorbed fraction. When the container is then filled with a new product, the gradient reverses and the absorbed molecules migrate back out over the following weeks.
This is why a washed fragrance tote still smells six months later, why solvent totes are permanently restricted to solvent duty, and why no quantity of chemistry, temperature or dwell time restores food grade. If you can smell it, it is coming out of the wall.
What this means practically
- Grade moves downward freely and upward never.
- Odour is a disqualifying observation, not a cosmetic one.
- If a bottle is permeated and you need a clean one, the answer is rebottling — a new bottle in the existing cage — not a harder wash.
- Any supplier offering to “convert” a chemical tote to food grade is selling a liability.
Four-question verification
- 1. Can you send the prior-contents affidavit?
- 2. Which wash chemistry was used?
- 3. Is the food line physically separate from caustic?
- 4. May I smell the inside before I accept it?
A supplier who cannot answer all four has not got a food-grade container. These are the questions our own customers ask us, and we would be concerned if they stopped.
Short answer
Choosing
When each grade is correct
Over-specifying food grade is the single most expensive habit in this market. It is also, occasionally, exactly right.
| Application | Grade needed | Why |
|---|---|---|
| Drinking water storage | Food grade | Direct human consumption |
| Edible crop irrigation (contact) | Food grade | Water contacts produce |
| Syrup, brine, juice, edible oil | Food grade | Food contact, and your auditor will ask |
| Brewing liquor and wort | Food grade | Food contact |
| Livestock drinking water | Food grade or rinsed | Lower risk, but avoid chemical history |
| Compost tea / worm leachate | Food grade | Output goes on food |
| Ornamental irrigation | Rinsed | No food contact anywhere in the chain |
| CIP caustic, plant chemistry | Reconditioned industrial | Not food contact — keep it a separate fleet |
| Ag chemical, fertiliser | Reconditioned industrial | Correct grade; food grade is a waste of money |
| Dust control, jobsite water | As-is or rinsed | Buy the cheapest sound unit |
| Ballast, counterweight | As-is | Grade is irrelevant |
Questions
Grade verification questions
What makes an IBC tote food grade?
Two conditions, both required. The bottle must be moulded from HDPE conforming to FDA 21 CFR 177.1520, and the container must have a documented history of food-contact use only. Compliant resin with an undocumented history is not food grade, and no wash process creates the documentation retroactively.
Can an industrial tote be washed to food grade?
No. HDPE is semi-permeable: over weeks of contact, organic molecules migrate into the polymer wall rather than merely sitting on its surface. A hot caustic wash removes surface residue and leaves the absorbed fraction, which then migrates slowly back out into whatever you put in next. The limit is material science, not effort.
How do I verify a food-grade claim?
Ask for the prior-contents affidavit from the original filler, and ask which wash chemistry was used. If the supplier cannot produce the affidavit, the claim is unsupported. If they mention caustic, the claim is wrong — food lines run hot water only. Then smell the inside: odour is permeation, and permeation disqualifies regardless of paperwork.
Is industrial grade safe to use?
Entirely, for what it is for. Non-food industrial liquids, ag chemicals, soaps, coolants, admixtures, dust control, non-potable water storage. Reconditioned industrial units are washed, tested and documented. They are simply not food-contact containers, and that is a statement about history rather than quality.
Does food grade mean the tote is sterile?
No. It means the materials and the history are acceptable. The container still needs sanitising before first use with a food-safe procedure — a tote that has sat dry for a season is not clean, whatever its grade.
Regulatory context
What the regulation actually says, and what it does not
FDA 21 CFR 177.1520 gets cited constantly and read rarely. Here is what it covers and the three things people wrongly believe it covers.
| Covers | Does not cover |
|---|---|
| The composition of olefin polymers used in food-contact articles | What the container subsequently held |
| Permitted monomers, additives and extractives limits | Whether a used container is fit for food service |
| The material as manufactured | Cleaning, sanitising or reconditioning processes |
| Suitability of the polymer for food contact | Chain of custody or prior-contents history |
That right-hand column is the whole argument. A bottle can be entirely compliant with the regulation and still be unsuitable for food service, because the regulation governs the material and says nothing about what the material has been used for. That gap is exactly where “FDA compliant resin” marketing lives.
Industry language
Terms used in place of food grade, and what each actually commits to
These phrases appear in listings constantly. None of them is a lie and none of them means food grade.
| Phrase | What it commits to | What it leaves out |
|---|---|---|
| "Food grade" | Compliant resin AND documented food-only history | Nothing — this is the full claim |
| "Food safe" | Nothing specific; no regulatory definition | Everything |
| "FDA compliant resin" | The polymer meets 21 CFR 177.1520 | The entire use history |
| "Suitable for food contact" | An opinion | Any evidence for the opinion |
| "Previously held food products" | Some fills were food | Whether all of them were |
| "Clean" | Nothing | Everything |
| "Washed" | A wash happened | Which chemistry, and whether it was the right one |
| "Triple rinsed" | Three water flushes | Whether anything was verified afterwards |
Short answer
- Only the first row is a complete claim
- "Food safe" has no regulatory definition at all
- Ask for the affidavit, not for reassurance
- If a supplier avoids the word "grade", notice that
From the Yard Journal
Longer pieces from the people who run the wash line, the test bay and the trading desk.
8 May 2025 · 4 min
Reading prior-contents affidavits like an auditor
Most affidavits are honest and useless. The difference between a document that protects you and one that does not comes down to four specific fields.
Nina Caldwell · Trading desk
Read27 February 2024 · 4 min
Why food-grade supply collapses every August
It is not demand. Documented food-contact stock depends on affidavits, and affidavits depend on somebody at a beverage plant having time to sign one.
Nina Caldwell · Trading desk
Read28 August 2025 · 4 min
Rain barrels, food grade, and the conversation we have every spring
Somebody wants one tote for a vegetable garden. The honest answer takes four questions and occasionally costs us the sale.
Marcus Vreeland · Founder
Read
Next move
Tell us what goes in it and we will tell you the grade.
Including when food grade is not required — which is more often than people expect, and saves real money. We would rather sell you the cheaper grade that works.