itna dry nahi karna hain. then, wet sponge, sqeeeze out all the water, wipe a small portion, again dip, and squeeze out all the putty by dipping the sponge, as you would for mopping the floor, then dip in clean water again, squeeze out all the water and repeat this process. aap ko a-xacto knife se scraping karna nahi parega. hope this helps someone. I learnt this the hard way.