Both blockout constructions stop light show-through for double-sided printing, but the core colour changes how the banner handles, ages and prints. Here is the practical difference.
Why a blockout core exists
A standard frontlit or backlit flex is translucent enough that artwork printed on one face can ghost through to the other. For a double-sided banner — a pole sign, a hanging mall graphic, a stage backdrop — that show-through ruins both images. A blockout banner inserts an opaque core layer between two printable faces so each side carries a clean, independent image.
Black back — maximum opacity
A black-core blockout delivers the highest light blocking. It is the safe choice for double-sided banners installed in or near lightboxes, or anywhere strong backlighting could still ghost through a grey core. The trade-off is a slightly stiffer hand and a heavier weight, typically 440–510 gsm.
Grey back — lighter and more supple
A grey-core blockout blocks enough light for the vast majority of front-lit double-sided installs while remaining lighter and more supple than a black core. It drapes more easily on hanging banners and puts less load on pole hardware. For street-pole banners and suspended indoor graphics lit only from the front, grey back is usually the better fit.
Double-printing banner — the lighter alternative
If your double-sided display tolerates some light transmission — festival banners, street decoration, retail windows — a double-printing banner skips the heavy blockout core entirely. It accepts independent artwork on each face at a much lower weight (280–340 gsm), which keeps freight and hardware costs down.
Choosing between the three
Use black back when backlighting is present or maximum opacity is non-negotiable. Use grey back for front-lit double-sided banners where weight and drape matter. Use double-printing banner for lightweight double-sided display where some translucency is acceptable. If you are unsure, describe the install and we will pick the construction for you.
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Hangzhou Nuclear Coating Fabric Co., Ltd.
