Should I cover meat with foil while it roasts?

Foil does one thing: it traps the moisture leaving the meat and holds it against the surface. Everything else follows from that. Wet surfaces cannot exceed 100°C, so they cannot brown, but they also cannot dry out and harden.

Step by step

1. Decide what you want from the surface.Crust, crackling and crisp skin are dehydration phenomena. They need dry air and a surface above 100°C. If the joint's appeal is its outside — a rib of beef, a pork joint with crackling, a roast chicken — do not cover it at any point except as a targeted shield.
2. Cover for long collagen cooks.A shoulder, a brisket or a rack of ribs is in the oven for four to six hours. Uncovered, the outer centimetre becomes leather long before the middle is ready. Foil keeps the surface humid so the whole joint arrives together, and you take the foil off for the last 30 minutes to build colour.
3. Use foil as a shield, not a lid, when something is running ahead.A loose piece over the breast of a turkey, or over the exposed bones of a rack, blocks radiant heat from the element without sealing in steam. This is the most useful application of foil in roasting and it can be applied mid-cook the moment you see a problem developing.
4. Understand that covering slows the cook down.A covered joint reaches a lower surface temperature, so heat moves into it more slowly. Expect a covered roast to take noticeably longer than an uncovered one at the same setting. Do not adjust upwards to compensate on a long cook — the point of covering is the gentle surface.
5. Cover loosely for resting, and only loosely.A tent of foil over resting meat holds warmth without sealing it. Wrapping tightly traps steam against crackling or crisp skin and destroys it in five minutes. If the meat has a crisp surface you care about, rest it uncovered somewhere warm instead.
6. Know the middle option.A lidded casserole does the same job as foil, more effectively, and gives you the juices in a usable form. A tin loosely covered with a sheet that is not sealed at the edges is somewhere between the two — some steam escapes, some browning happens. That halfway state suits joints like a turkey crown.

Tips

• Foil directly against a browning surface will pull skin off when you remove it. Tent it so it does not touch, or use a sheet of baking paper underneath.
• Salted, acidic liquids in prolonged contact with aluminium foil can pit it. For an overnight covered cook in a tomato or vinegar-heavy liquid, use a lid or baking paper under the foil.
• The 'Texas crutch' — wrapping a brisket or shoulder tightly in foil partway through — is the barbecue version of the same idea, used specifically to push through the temperature stall.
• Butcher's paper is the compromise barbecue cooks prefer: it holds some moisture but breathes, so bark survives better than under foil.

Common mistakes

• Covering a roast chicken or a pork joint for the whole cook — You are steaming it. The skin goes pale and rubbery, the crackling never happens, and the meat tastes boiled rather than roasted.
• Wrapping crackling in foil to rest — Trapped steam softens it within minutes. Rest crackling separately and uncovered, or on a rack in a warm place.
• Taking the foil off too late on a long cook — Colour and bark need real time at high heat. Thirty to forty-five minutes uncovered at the end is the minimum on a big joint.

Questions people ask