(Quoted from Arlon Graphics and Sign & Digital Magazine. Full article here.)
The shelf life of vinyl film is primarily determined by a.) the amount of plasticizing oils which transfer into the adhesive coating, and b.) the sensitivity of the affected adhesive to plasticizer contamination when it is fully saturated or contaminated. To some extent, shelf life is dictated by product formula of film and adhesive but is also strongly affected by storage conditions at the distributor and end-user facility. A sign shop that keeps its film properly stored can expect to use it for significantly longer than the indicated shelf life with minimal risk, while an overheated or wet storage condition will invariably cause problems.

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