Tinplate is mainly used for canning of food and beverages. Tinplate producers are quite a handful compared to most other types of coated steel like HDG.
What is the main difference between tinplate, tin free steel and blackplate?
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Blackplate
Blackplate is a substrate/feedstock/raw materials used to make tinplate and tin free steel/ECCS.
Blackplate is a thin, low carbon and is in a cold reduced steel coil form.
Backplate is sometimes confused with a black coil which is a totally different form of steel. Black coil steel is actually an untreated hot rolled coil.
Blackplate can be available in single-reduced or double-reduced forms. The double reduced form is used for more hardness and strength.
Beside making tinplate, blackplate can be used as a substrate for many other applications such as enamelled hollowware, pre-painting (organic coated steel), dry battery jackets etc.
Tinplate
Tinplate is a type of cold rolled sheet which is coated with a thin layer of tin. Tinplate is resistant to corrosion and ideal for food packaging/canning.
It is estimated that nearly 90% of tinplate goes to the packaging industry. Food and beverage sectors account for the largest market share. Tinplate is also used in non-food packagings such as aerosols, home care, healthcare and chemicals.
The tinplate industry is highly concentrated with the top five tinplate producers account for around 50% of the global market.
During the tinplate making process, tin is applied on the blackplate (feedstock) in a continuous process where the decoiled steel passes through an electrolytic plating bath containing tin in solution.
There is a range of coating thickness depending on applications. The tin coating thicknesses can be applied on either side of the sheet. The typical thickness can be in the range of 0.13-0.49 mm. The coating on each side is typically in the range of 2.8-5.6 grams/sq metre but can be 1-14 g/m2.
Tin Free Steel/ECCS
Blackplate is also used to make tin-free steel. Tin free steel is also known as ECCS (electrolytic chromium coated steel). ECCS is cold rolled coil corrosion-resistant steel, but instead of tin, it is coated with a thin coating surface layer of metallic chromium and chromium hydroxide. Its main application is in the packaging sector, but can also be used in other applications such as electrical equipment.
ECCS is produced by applying a thin layer of chromium and chromium oxide coating on a cold-rolled, low-carbon steel coil substrate in a continuous electrolytic process using chromic acid.
One of the advantages of ECCS on tinplate is that ECCS can be recycled as tin is a contaminant in scrap.