The sheet can be smaller than the frame.
Do magnets stick to sheet metal.
The academic term for materials that do not attract magnets is diamagnetic.
Galvanized steel is made by dipping steel into molten zinc.
Wood and metal frames are not necessary.
We use inexpensive plastic frames.
Iron is found in steel so steel attracts a magnet and sticks to it.
Magnets do not stick to non metal materials.
Magnet sheets with adhesive 8 x 10 inch magicfly pack of 15 flexible sticky magnet sheet crafts photos and more easy peel and stick by magicfly 4 6 489.
The weaker metal will not attract the magnet but the addition will.
Finally make sure that when you order your item you tell the provider you are making a magnetic board and that you require the material to be flat and free of any surface imperfections or dents.
Most people know from experience that magnets do not stick to non metal materials such as wood plastic fiberglass and textile.
However the cost will be higher do not use pre painted aluminum sheet as it does not have any magnetic properties.
30 gauge sheet can usually be found at building supply stores in sections that carry heat ventilation and air conditioning ducting.
Magnets will not stick to aluminum copper brass etc.
Even though the galvanization process involves coating the steel with zinc a nonmagnetic metal the magnetic properties of the steel are not hindered by the zinc coating.
Iron or steel are often added to other metals to make them stronger.
About the tin sheet.
Steel is an alloy of iron and carbon which makes it ferromagnetic due to its high iron content.