Frequently Asked Questions

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Is the bottle cap plastic?

No. The cap is stainless steel, with one food-grade silicone ring so it doesn't leak.

Almost every steel bottle on the market closes with plastic. Hydro Flask, in their own FAQ: "All of Hydro Flask's caps are made out of BPA/BPS free polypropylene." Chilly's, Stanley and Mepal are the same. Klean Kanteen — the most credible plastic-free brand in the category — ships polypropylene caps as standard and charges extra for one that isn't.

Ours is steel as standard, and it costs less than all of them.

So your containers aren't really plastic-free?

Correct — and we would never say they were.

There are two materials in everything we make: 304 food-grade stainless steel, and one food-grade silicone seal so it doesn't leak. That is the entire list, across the whole range, lids and bottle caps included.

What we will say is narrower and completely true: no plastic touches your food.

We say two, out loud, because nobody else in this category would ever volunteer a number greater than one. They all round down. We would rather you counted. If a third material ever appears, it goes on the page before it goes in the box.

Why we won't use the phrase "plastic-free".

Is silicone a plastic?

No, though we understand why the question comes up.

Silicone is a synthetic polymer, but it is built on a silicon–oxygen backbone rather than the carbon chains that define plastics. It behaves differently: it doesn't soften and warp with heat the way polypropylene does, it doesn't rely on plasticisers to stay flexible, and it stays inert across a much wider temperature range.

Regulators, chemists and most people treat it as its own category — and every serious plastic-free brand in this industry uses silicone somewhere and doesn't count it.

We could hide behind that. We would rather just tell you the seal is there, tell you why, and sell you a spare when it wears out.

More on why we use a silicone seal.

Is it BPA-free?

There is no plastic in our containers, so there is nothing here for BPA to be in.

But we won't print "BPA-free" on anything, and that is deliberate.

BPA was removed from plastics after concerns were raised — and in many cases replaced with another bisphenol (bisphenol S, bisphenol F), which is chemically related and far less studied. A product made with bisphenol S is, truthfully and legally, BPA-free. In 2024 the EU went after the substitutes too.

"BPA-free" is the incumbents' word, it describes an absence rather than a substance, and it is one substitution away from being the wrong reassurance again. We would rather tell you what is in the product.

The truth about "BPA-free".

What grade of stainless steel do you use?

304 — also written 18/8 — in every product, at every size and every price. Body, lid, divider, bottle cap.

This matters more than it sounds. "Food grade" is not a single standard: 201, 202, 304 and 316 all get sold under that phrase, and they are not the same material. 201 and 202 substitute cheaper manganese for some of the nickel, which makes them less resistant to corrosion — in exactly the conditions a food container lives in.

Some brands in this category use them. ECOlunchbox discloses 201 in its own FAQ; Onyx states 202 on its own product page. We print the number, because "food grade" is what you say when you would rather not.

Is "food grade" a real standard?

Does stainless steel leach nickel into food?

The honest answer, including the inconvenient parts.

Yes, trace amounts of nickel and chromium can migrate from stainless steel — this is real and published. But the research everyone cites (Kamerud et al., 2013) simmered tomato sauce at around 85°C for six to twenty hours. That is a study about cooking, not storing. Nobody simmers sauce in a lunchbox. Migration also drops sharply after the first few uses.

We are not going to tell you "steel doesn't leach" — no study of cold-storage migration from 304 exists, so nobody can honestly prove that negative.

And roughly 10–15% of people in Europe are nickel-sensitive. 304 steel contains nickel — it is in the name, 18/8. If you have a diagnosed nickel allergy and have been advised to limit dietary nickel, speak to your doctor before choosing steel food storage. Please don't just take our word for it; we sell the stuff.

The full answer.

Is stainless steel better for the environment?

Not automatically, and we are not going to claim otherwise.

In December 2023 the Consumentenbond published research concluding that stainless steel bottles are "veruit het slechtst voor het milieu" — by far the worst for the environment — and that you would need to use one for more than 36 years to match the impact of a reusable PE bottle. The reason is production: making steel is energy-intensive in a way that making plastic is not.

That footprint is paid once, up front. The only thing that can justify it is keeping the thing. Which is why we guarantee the steel for ten years and sell you a €4 seal instead of a new container.

If your current plastic containers are working fine, keep them. That is the environmentally correct answer, and we are not going to give you a different one.

The full, uncomfortable version.

Is the lid plastic?

No. The lid is 304 stainless steel, the same as the body.

This is unusual, and it is the single most important thing to know about us. Almost every food container you can buy — steel or glass, cheap or expensive — closes with a polypropylene lid. Chilly's, Stanley, Hydro Flask, Mepal, IKEA, Bentgo. And every glass container sold in the Netherlands, without exception.

Your food spends three days in the fridge pressed against the lid. It is the surface with the longest contact time and the least scrutiny. Ours is steel.

See the whole category, lid by lid.

Is stainless steel safe for food?

304 stainless steel has been the standard in professional kitchens, food processing and medical environments for decades — because it is stable, non-reactive and does not rely on coatings or additives.

We want to be precise about one thing, though: we are not claiming steel is "more regulated" than plastic. It isn't. Metals are one of the non-harmonised material groups in the EU — there is no EU-wide regulation specifically for stainless steel in food contact, only guidance.

The honest claim is simplicity, not superior oversight. A plastic container is a formulation — a polymer plus stabilisers, plasticisers, colourants and processing aids. A 304 container is an alloy of a handful of named elements. There is less to know, and less that can change without anyone telling you.

If you have a nickel allergy, see our answer on nickel above.

Can I put it in the freezer?

Yes. Steel handles cold without becoming brittle, and it will not crack the way glass can.

Two practical notes: leave a little headspace, because food expands as it freezes, and let the container come up to room temperature before you try to prise the lid off — a very cold seal is a stiff seal.

Can I put stainless steel containers in the microwave?

No. Metal does not go in a microwave — not ours, not anybody's.

This is a real disadvantage and the most common reason people decide not to buy from us. We are not going to spin it.

If reheating in the same container you stored it in is non-negotiable for you, buy glass — with our blessing. Just look at its lid first, because that is almost always polypropylene too.

And it is worth knowing what the label on your current container actually promised: "microwave-safe" only ever meant the box wouldn't melt. It never said anything about your food.

How to reheat without a microwave · What "microwave-safe" actually means

Can I put it in the oven?

We have not tested our containers for oven use, so we are not going to tell you it is fine.

The silicone seal is not designed for oven temperatures, and the lid should never go in. Use a dish you know is oven-safe.

This is the sort of question where most brands would give you a confident answer they hadn't earned. We would rather say we don't know.

Can I store acidic foods like tomato sauce?

Yes, for normal storage. Tomato, citrus and vinegar dressings in the fridge overnight or for a few days are fine.

What is different is cooking: simmering an acidic sauce in steel at temperature for many hours increases interaction with the metal. That is the condition the research on metal migration actually studied — and it is not what a food container does.

Store your ragù in it. Don't simmer your ragù in it.

Can stainless steel rust?

Rarely — but we are not going to say never.

304 stainless steel is highly corrosion-resistant thanks to a self-repairing chromium oxide layer on the surface. But it can pit if it is left wet, in prolonged contact with salt or bleach.

Rinse and dry after washing, and avoid aggressive cleaners.

And if it does rust, that is our problem, not yours. Our ten-year guarantee includes rust. Some brands in this category advertise a lifetime guarantee and quietly carve rust out in the small print — which tells you they expect it to happen. Read the guarantee.

Will it dent?

Yes, if you drop it on a hard floor. Steel dents where glass shatters and plastic cracks.

A dented container still closes, still seals, and is still exactly as safe to eat from — which is the part we actually guarantee. We are not promising your container will look new in ten years. We are promising it will still be steel, and still doing its job.

Dents are not covered by the guarantee. Rust, pitting, cracking and wearing through are.

Does stainless steel absorb smells or stains?

No. Steel is non-porous — it does not absorb odours or flavours the way plastic can. Sunday's ragù does not become Wednesday's smell.

If you notice residue from strong foods, wash with warm soapy water. For stubborn smells, a baking soda paste or a splash of vinegar helps.

The one part that can hold on to a smell is the silicone seal, because it sits in a channel. Take it out and wash it separately every so often.

Are your containers dishwasher safe?

Yes. Place lids on the top rack and let everything dry fully before storing.

Remove the silicone seal occasionally and rinse it separately — it is the one part where residue can collect, and it is designed to come out.

Dishwasher cycles are also what eventually wears the seal out, which is normal and not a defect. When it stops springing back, buy a new one rather than a new container.

Is it safe for children's lunches?

It is built for exactly that. The lids are steel, the bottle cap is steel, and the containers do not shatter when a school bag gets dropped.

We will not tell you that plastic is harming your children. Nobody can honestly tell you that, and brands that imply it are selling you fear at a markup.

What we will tell you is what is in the box: 304 stainless steel and one food-grade silicone seal. That is the entire list. You can decide what to do with it.

One practical note: steel is heavier than plastic, and for a small child a full 1400 ml container is a lot to carry. The 800 ml lunch box and the 480 ml snack pot are the sizes most parents end up using.

My lid has stopped sealing properly. What now?

It is almost certainly the silicone seal, and it is almost certainly not broken — just tired.

First, take the seal out and check it is seated correctly in the channel, all the way round. A seal that has been washed and refitted in a hurry is the most common cause.

If it is seated properly and still leaks, press it with a fingernail. If it does not spring back, it has compressed and needs replacing. That is normal after a few years of daily use.

Buy a replacement seal — choose the size that matches your container.

Can I buy a replacement seal?

Yes. Always, and for as long as you own the product.

Each seal is cut for one specific lid, so choose the size that matches what you own — a 480 ml seal will not fit a 1200 ml lid, and the bottle cap ring fits nothing else.

They fit The Stainless Co. products only. Seal geometry is specific to the lid it was designed for, and we would rather you bought nothing than bought something that doesn't seal.

For context on how unusual this is: Glasslock states on its own site that "the gaskets are not available as a separate replacement part." Pyrex's warranty excludes the lid entirely.

Replacement seals.

How do I claim on the guarantee?

Email hello@thestainless.co with your order number and a photo. That is the whole process.

If it is covered, we send you a new one.

Why doesn't the guarantee cover the silicone seal?

Because silicone wears out, and we would rather tell you than let you find out.

After a few years of dishwasher cycles it compresses, loses its spring, and stops sealing the way it did on day one. That is not a defect. It is what silicone does, and no guarantee on earth can stop it.

So we do not make a promise we cannot keep. We sell you a new one instead — a few euros, for as long as you own the product.

A company that sells you a €4 spare part is a company that expects you to still own the product in five years. We think that is worth more than a promise with a footnote.

Replacement seals.

What does the ten-year guarantee cover?

Ten years on the steel. Every 304 stainless steel part of everything we sell — body, lid, divider, bottle cap.

If it rusts, pits, cracks or wears through in normal domestic use within ten years of purchase, we replace it. No cost to you. Rust is included, not excluded.

Not covered: the silicone seal (it is a consumable — we sell you a new one instead), dents and cosmetic marks, and misuse such as bleach, abrasive cleaners or oven use.

This guarantee is offered in addition to your statutory rights under Dutch and EU consumer law. It does not replace them.

Read the full guarantee.

What is your return policy?

You can request a return within 30 days after receiving your order. Items must be unused, in original condition, and in the original packaging. To start a return, contact hello@thestainless.co with your order number.

My item arrived damaged or incorrect. What now?

Please contact us immediately at hello@thestainless.co and include your order number plus photos of the item and packaging. If the item is confirmed defective or incorrect, we will make it right and cover any necessary shipping costs.

Can I exchange a product?

The fastest way to get a different product is to return the item you have and place a new order once the return is approved. If you need help choosing the right item, contact hello@thestainless.co.

When will I receive my refund?

After we receive and inspect your return, we will notify you of the outcome. If approved, refunds are issued to your original payment method within 10 business days. Your bank or payment provider may take additional time to process the refund.

Who pays for return shipping?

Return shipping costs are the responsibility of the customer, unless the item is defective or you received the wrong product. We recommend using a trackable shipping method for your return.

Where can I find my invoice?

Your order confirmation email serves as proof of purchase and includes your order details. If you need an invoice for your administration, contact hello@thestainless.co with your order number and we will help.

How do I place an order?

Simply add your items to the cart and proceed to checkout. You will receive an order confirmation email right after payment. If you notice an error in your order details, contact us as soon as possible at hello@thestainless.co.

Can I change or cancel my order after placing it?

We process orders quickly, so changes or cancellations cannot be guaranteed once an order is confirmed. If you need help, email hello@thestainless.co immediately with your order number. If the order has not shipped yet, we will do our best to assist.

What payment methods do you accept?

Available payment methods are shown at checkout and may vary by country. We support common options such as card payments and local methods where available. If you are unable to complete payment, contact us at hello@thestainless.co.

How long does delivery take?

Delivery times are estimates and depend on your location. Typical delivery times are: Netherlands 1-3 business days, Belgium 2-4 business days, and other EU countries 3-7 business days. You will receive a tracking link as soon as your order ships.

How much does shipping cost?

Shipping costs are calculated at checkout and shown before you pay. We may offer free shipping promotions from time to time, which will be clearly communicated on the website and during checkout.

Do you ship internationally?

We currently ship within the European Union. If your country is not available at checkout, contact hello@thestainless.co and we will let you know if we can help.

How can I track my order?

When your order ships, you will receive an email with a tracking number and a direct tracking link. You can also view your order status by logging in with the email address you used to order, even if you did not create a password.

My tracking hasn't updated yet. What should I do?

Tracking updates can take up to 24 hours after you receive the shipping confirmation email. If nothing changes after 48 hours, contact hello@thestainless.co and we will check it for you.

What if my package is delayed or lost?

Delivery estimates can be affected by carriers, weather, or peak periods. If your order is significantly delayed, contact us and we will investigate with the carrier. If a shipment is confirmed lost, we will arrange a replacement or refund.