A putty knife or spackle knife (called a 'scraper' in British English, and also known as a spatula in American English) is used for scraping surfaces, or spreading material such as plaster in various construction trades. Widths from 1 1/4" to 5" or 6" are commonly available. Stiff-blade knives, typically 1 mm or .040" thick, are suitable for scraping. Flexible-blade knives, typically 0,5 mm or .020" thick, are suitable for spreading. Disposable knives, with handle and blade molded as a single piece of plastic, are suitable for occasional jobs such as spreading roof patching tar, where cleanup may involve hazardous solvents. Blade Types: Small blades from .5" up to 2" are generally used for Readypatch or similar products in filling small imperfections. Larger blades such as 5" to 12" are used for sheet rocking. Larger blades are made, but generally lack the stability of the smaller blades and do not make a perfectly flat surface. Blade Materials: Most blade material for these knives are made from low grade steel. Usually spring steel is employeed in this instance. Higher quality knives use better steel that is resistant to rusting easily. Some very high quality knives use Titanium as a blade material. Titanium blades are often expensive, but are better to make yourself if you are qualified. Handle Materials: Wood is usually the best choice in handle material. It usually is only used on more expensive knives. Plastic handles are more wide spread than the wood handles due to low manufacturing costs. It is uncommon to have exotic woods as a handle material.
