Apart from size, other factors include complexity, age, contamination and the amount of glass missing from the surface. Also the repair can only be made to the outside layer of glass. A laminated windscreen has two inside and out, if the inside layer is damaged then nothing can be done. Contamination is usually a result of the damage being wet, water carries contaminates into the damage and prevents an effective repair, and can leave a disappointing result. While the damage is wet it cannot be repaired, however after it has dried it may be possible to still repair the windscreen providing there is not too much contamination. The main objective is to fill the damage gluing the crack together preventing it from spreading.

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