Take care when dissolving NaOH crystals in water – the reaction is strongly exothermic and the resulting solution may be hot enough to soften a plastic bucket and allow it to collapse (you may detect the voice of experience here – though it was more of a dustbin than a bucket).
Its best to use cold water, and add the NaOH gradually, with stirring.
It works a treat, and its cheaper than proprietary strippers.