Slow Cooker Liners and Instant Pots
why the bag that saves your Crock-Pot will not save your pressure cooker
And what actually works instead

Reynolds Kitchens sells hundreds of millions of slow cooker liners every year, and for good reason — they turn a baked-on chili nightmare into a two-second bag-and-toss. So it's a perfectly logical leap to wonder whether the same trick works in an Instant Pot. The short answer is no, and the reason matters more than just "the manufacturer says so."

This article explains the actual physics of why those liners are incompatible with pressure cooking, what specific risks you'd be taking, and — because the underlying problem is real — the options that genuinely do make Instant Pot cleanup easier without compromising safety.

What slow cooker liners are actually made of, and what they're rated for

Reynolds Kitchens Slow Cooker Liners, the dominant brand in the US market, are made from BPA-free nylon resin. Reynolds rates them for temperatures up to 400°F (204°C) in dry heat and specifies they are designed for slow cooker use only. That 400°F ceiling sounds generous until you understand what happens inside an Instant Pot.

A standard slow cooker operates at roughly 190–210°F on its high setting, with the lid sitting loosely on top and steam escaping freely. There is no meaningful pressure buildup. The liner just sits there, keeping the ceramic insert clean, and the temperature never challenges the nylon.

Other brands — including the store-brand versions sold by Walmart and Target — use similar nylon or polyester formulations. None of them are rated for pressurized environments. The rating is always for atmospheric pressure at a specified temperature, not for sealed, pressurized steam.

It's also worth noting that Reynolds explicitly states on the packaging: "Not for use in pressure cookers." That's not legal boilerplate. It reflects a real engineering limit of the material under combined heat and pressure conditions.

The actual risks inside a pressurized environment

An Instant Pot Duo (one of the most common models) reaches roughly 239–245°F (115–118°C) at its standard high-pressure setting, with internal pressure around 10.2–11.6 psi above atmospheric. That combination — elevated temperature and pressure — is categorically different from what a slow cooker liner is built to handle.

Here is what can go wrong, in order of likelihood:

1. The liner deforms and blocks the steam vent or float valve. The inner pot's steam vent and float valve are at the top of the cooking chamber. A liner that shifts, bubbles, or partially melts can send material toward those openings. A blocked float valve means the lid cannot confirm the pot has depressurized, and a blocked steam vent is the setup for a dangerous over-pressure event.
2. The liner partially melts and leaches material into food. Even if the nylon stays structurally intact, heating nylon beyond its design parameters under pressure can accelerate the migration of oligomers and other compounds into food. This is genuinely uncertain territory — no one has published a rigorous study on exactly what transfers — but the uncertainty itself is the problem.
3. The seal fails and the pot cannot reach pressure. A liner that traps air between itself and the inner pot wall can prevent the liquid from circulating properly, causing the Instant Pot to display a "burn" warning or simply never reach pressure. This is the least dangerous outcome, but it still means a failed meal and a messy cleanup anyway.
4. The liner fragments under steam pressure. Sustained pressure cycling degrades polymer materials faster than steady heat. Tiny fragments in your food are not a hypothetical — this is exactly why pressure-rated cookware uses stainless steel, silicone, and tempered glass rather than nylon.

Why this confusion is so understandable — and how Instant Pot marketing made it worse

Instant Pot's own branding leans hard into the slow cooker comparison. The Instant Pot Duo 7-in-1 markets itself as a slow cooker replacement, and many people buy it specifically to replace a Crock-Pot. The inner pot even looks vaguely similar — a round metal container that sits inside an outer housing. If you've been using slow cooker liners in one appliance, the visual similarity makes it feel like the same solution should apply.

There's also a real and valid underlying frustration. Instant Pot's stainless steel inner pot is genuinely hard to clean after anything with dairy, tomato paste, or sugars that caramelize under pressure. The burn layer that forms on the bottom after a pressure cycle with thick sauce is stubborn in a way that a slow cooker's ceramic insert usually isn't. The desire for an easy-cleanup solution isn't irrational.

Instant Pot (now owned by Instant Brands) has also sold silicone accessories through its own store, which muddies the water. Some third-party sellers on Amazon have listed nylon-style accessories that look like liner bags without clearly stating they are pressure-rated. Reading reviews, you'll find people who tried it once, had no visible problem, and wrote a five-star review — which is exactly how dangerous shortcuts get normalized before the failure case shows up.

The short version: the appliances look related, the problem they solve feels identical, and the market has not done a great job distinguishing them. That's why this question gets typed into Google thousands of times a month.

What you can safely use instead

There are several genuinely effective alternatives for making Instant Pot cleanup easier. They vary by cooking style and what you're making.

Silicone liners made specifically for Instant Pot

Several manufacturers make silicone pot liners sized for 6-quart and 8-quart Instant Pots. Silicone is rated for temperatures well above what an Instant Pot reaches — food-grade silicone typically tolerates up to 450–500°F — and it has no issue with the pressure involved. Brands like Baking With Butter and OXO make Instant Pot-specific silicone inserts. These are genuinely useful for things like oatmeal, yogurt, and soups where the cleanup is the worst part.

The tradeoff: silicone conducts heat less efficiently than stainless steel, which can affect sautéing. For recipes where you're browning meat first using the Sauté function, the silicone liner will underperform. Pull it out for the sauté step, then drop it back in for pressure cooking — or just accept that silicone liners are best for liquid-heavy recipes where sautéing isn't involved.

Parchment paper for specific applications

Parchment paper is FDA-approved for temperatures up to around 425°F and does not have the pressure sensitivity that nylon does. In an Instant Pot used for steaming or pot-in-pot cooking (where the parchment never touches pressurized liquid), it can work. It is not a substitute for a liner in the main cooking chamber — you can't line the inner pot with parchment the way you'd line a slow cooker. But for making steamed dumplings on a trivet, for example, parchment placed on the trivet works fine.

Pot-in-pot cooking

This is probably the most underused technique for Instant Pot cleanup. You add water to the main inner pot, set a trivet inside, and place a separate oven-safe bowl or pan on the trivet. Your food goes in that secondary vessel. The main pot only ever has water in it, which is trivial to clean. Pyrex dishes, Instant Pot's own ceramic nesting bowls, and Fat Daddio's anodized aluminum pans all work well for this. For cheesecakes, rice dishes, and egg bites, pot-in-pot is the professional solution.

Soaking immediately after cooking

Not glamorous, but effective: fill the inner pot with warm water as soon as you've served the food. The residual heat from the pot helps loosen anything stuck. Ten minutes of soaking does the work that half an hour of scrubbing otherwise requires. For anything with tomato or dairy, add a squirt of dish soap to the soak water. This costs nothing and has no safety implications.

The inner pot itself is dishwasher safe

Instant Pot's stainless steel inner pot is rated dishwasher safe. This doesn't help with the scrubbing required to get the pot into a state where the dishwasher can finish the job, but it means you're not hand-washing the whole thing — just the pre-treatment.

The Instant Pot slow cooker mode is a separate question

Here's a wrinkle worth addressing directly: the Instant Pot has a dedicated slow cooker function. When you use that mode, the lid is on, but there's no pressure seal — you're supposed to use the Instant Pot tempered glass lid (sold separately) rather than the locking pressure lid. The float valve is not engaged. Does that change things for slow cooker liners?

Technically, the temperature profile is closer to what the liner is rated for. The Instant Pot's slow cooker mode runs at around 190–210°F on the "More" setting, similar to a traditional slow cooker's high setting. The pressure argument goes away because the pot isn't sealed.

However, Reynolds still rates their liners specifically for ceramic and porcelain slow cooker inserts, not for stainless steel pressure cooker pots. The fit is wrong — slow cooker liners are sized for oval ceramic Crock-Pot inserts, not round stainless steel Instant Pot inserts. A loose, ill-fitting liner in a slow cooker mode Instant Pot is a folding, bunching mess that can easily touch the heating element or get caught in the lid mechanism.

More practically: the Instant Pot's slow cooker function is widely regarded as inferior to a dedicated slow cooker. Consumer Reports and serious home cooks like J. Kenji López-Alt have noted that the Instant Pot runs hotter and less evenly in slow cooker mode compared to a real Crock-Pot. Most people who care about slow cooker results keep their Crock-Pot. If you're using the Instant Pot's slow cooker mode, you're likely already compromising on results — adding an ill-fitting liner to that doesn't improve the situation.

Bottom line: even in slow cooker mode, the case for using a slow cooker liner in an Instant Pot is weak. The physical fit is poor, and the silicone alternatives work better for both pressure cooking and slow cooker mode.

What to do with the box of slow cooker liners already in your cupboard

They work exactly as advertised in any traditional slow cooker — a Crock-Pot, a Hamilton Beach, a KitchenAid slow cooker, any of them. Reynolds liners fit most standard 3–8 quart oval slow cookers well. If you still own a slow cooker or cook for anyone who does, the liners are genuinely useful there.

They also work as a mess-reduction tool for marinating. Place your meat and marinade in the liner inside a bowl, tie the top, and refrigerate. You get the benefit of the bag without dirtying the bowl. It's a small thing, but it's legitimate.

Some people use them to line large serving bowls at parties when they want the food kept warm in a slow cooker at the table. That is exactly the use case they're designed for.

What they are not: a pressure cooker accessory, a reusable bag, a sous vide pouch, or a safe steaming vessel. Nylon is not rated for submersion in boiling water under pressure. Use them in their intended domain and they're excellent. Ask them to do something they were never designed for, and the result ranges from a failed meal to an actual safety hazard.

How to choose the right silicone liner for your specific Instant Pot

If you decide to go the silicone liner route — which is the most direct functional replacement for what you'd be trying to do with a slow cooker liner — the key specifications to match are pot size and shape.

The most common Instant Pot sizes are 3-quart, 6-quart, and 8-quart. Silicone liners are sold by pot size. A 6-quart liner will not fit properly in an 8-quart, and using an oversized liner creates the same bunching and fit problems as using a slow cooker liner. Check the dimensions of your inner pot and match them to the liner's listed dimensions, not just the quart size — third-party liners sometimes use quart sizing loosely.

Look for liners rated at food-grade silicone (usually labeled FDA-approved or LFGB-compliant, the European food-safety standard). Cheaper silicone products sometimes use fillers that compromise heat resistance. A simple test: pinch and twist an unheated silicone product sharply — if white shows in the fold, there's likely filler material present. Pure silicone stays the same color when deformed.

Silicone liners with handles are meaningfully easier to work with. Lifting a silicone pot full of hot soup out of an Instant Pot is awkward, and handles give you control. It sounds like a minor feature; it isn't.

Expect to pay $10–20 for a decent silicone liner. At that price, it's worth having two: one in use, one clean. The ones I'd actually buy are the OXO Good Grips Silicone Pressure Cooker Liner (available for 6 and 8 quart models) and any LFGB-certified insert from a brand that lists its silicone grade. Generic Amazon listings with no material certification are not worth the uncertainty.