Am I using foil the wrong way round?

I did think the other day, is this the right way up?

However, if it comes off the roll with the shiny side up, I would tend to put it over the food with the shiny side uppermost I think, that's the way it cuts easily on the sharp edge.

I've always used it shiny side up, too.

I've always used it shiny side in but have read somewhere recently that it doesn't matter. I'll still use it shiny side in!

Yep, shiny side up for me too. Surely if that's the way it comes off the roll, then that's the way it should be used? (Actually, does it really make any difference which way round it's used? )

I found this online, which seems pretty definitive to me.

americastestkitchen.tumblr.com/post/5546338699/foil-shiny-side-up-or-down

The reason for the different finish on each side is due to the production process, the last rolling is two thickness's, which enable then to make it thinner, when the two layers are separated the inside is matt. I doubt it makes much odds which way you use it.

Crossing posts. I got my ifno from "How it's made" on Quest last week.

Indinana - thanks, I'll now use it however is easiest as it comes off the roll!

Shiny side up for a joint in the oven to reflect the heat away from the surface so outside doesn't over cook. So I've been told, seems to work.

I have been buying non stick foil lately and it's labeled so you know which side is which. I quite like it.

Graham Kerr the Galloping Gourmet was asked this question by an audience member. He replied that he always put the shiny side on the inside. The reason was that the shiny side would reflect the camera lights!

In my freelance catering days, I used to be in partnership with a Cordon Bleu trained cook and she always used it shiny side in when cooking, so I did ( and still do) too. For storing leftovers in the fridge, I would use it shiny side out , but I doubt whether it makes any difference any way!

I can't believe it makes any discernable difference .... just do what you want.

Don't daughters just love telling you they know better than you?

Good question, good answers!
Indinana I now have peace of mind . I did wonder (not in a losing sleep way you understand), but good to know!

I have read Indinanas link. As it is just a very thin sheet of aluminium I would have doubted that there would be much difference in heat transmission.

There used to be a TV chef (can't remember which one) who said shiny side down and after several programmes and viewers questions admitted it was so it didn't dazzle the cameras and that it didn't make any difference which way you used it.

Morning everyone , the shiny side should be down as it conducts the heat better.

Like Imp27 I did wonder. Good to know I wasn't alone... thanks for posting the solution.

I've always put the shiny side towards the food to reflect the heat if hot, and outside, for the same reason, if cold. I thought it was obvious, till I saw professionals even doing it the other way round, covering a turkey on a buffet when they noticed that everyone was helping themselves to a salad or starter and not going for the main course first time round. They put the shiny side outwards. I told them off.

I'm pretty sure we're talking about reflecting the heat here. Conducting heat would take it away from the food inside.

Pompa has hit the nail on the head, the difference in finish is just a by-product of the way it's produced, not for any performance reason:

"Aluminium foil has a shiny side and a matte side. The shiny side is produced when the aluminium is rolled during the final pass. It is difficult to produce rollers with a gap fine enough to cope with the foil gauge, therefore, for the final pass, two sheets are rolled at the same time, doubling the thickness of the gauge at entry to the rollers. When the sheets are later separated, the inside surface is dull, and the outside surface is shiny. This difference in the finish has led to the perception that favouring a side has an effect when cooking. While many believe that the different properties keep heat out when wrapped with the shiny finish facing out, and keep heat in with the shiny finish facing inwards, the actual difference is imperceptible without instrumentation. "

According to Wiki, the purpose of foil is to keep moisture in, not for keeping heat in or out, which makes sense to me.

For the technically minded, there are three ways heat can transfer :-

Conduction -when you put your finger on a hot pan (ouch) that is conduction.
Convection - this is the transfer of heat through the air - an electric fire
Radiation - this is usually infrared radiation. This is a type electromagnetic radiation eg The Sun.

Foil is very good at conducting heat, either way hot>cold or cold>hot. It will prevent convection because it forms a barrier and it will reflect radiation. But an oven primarily works through convection so the silver/matt side will not make much difference.

A thermos Flask works because it prevents all three types of heat transfer.

Glass is a poor conductor of heat
The silvering reflects radiation
The vacuum prevents convection.

It is not supposed to matter which way around!

Yes that's what I mean silly me