Scrapers remove paint and dirt. Anyone can scrape, but a bad scraper choice ruins surface finishes or makes work difficult.
==Hardness=Scraper behaviour is all about relative hardness. When 2 materials scrape against each other, the softer one deforms, with little effect on the harder one. This means 2 things: * to be an effective cleaner the scraper must be harder than the dirt/ paint etc * to avoid risk of damage the scraper should be softer than the workpiece
Hardness is measured in mohs, a non-linear scale with with diamond at 10 mohs, and soft talc at just 1.
==Surface damage=With many surfaces, microscopic damage matters. It causes: * loss of gloss or shine * for see-through materials, complete loss of clarity * it makes cleaning rather harder, which is an issue in the kitchen, and with plastic surfaces * gradual wearing off of thin surface coatings
===Wood==For some surfaces, microscopic damage doesn't matter. This is true of wood, and thus metal scrapers are usually used. The tough hard steel is long lived and rarely needs its edge grinding. Wood is low on the mohs scale at under 2.5.
===Glass==Glass and see through plastic are especially vulnerable to scraper action, since the results of surface damage are so visible. Glass is a very hard material at 5.5 mohs, but steel scrapers can sometimes cause scratching and abrasion as they're just as hard. Where glass is puttied it doesn't matter, as its covered over, and tiny scratch marks are a very small matter. Where the effects are more noticeable, steel scrapers are better avoided. Copper and aluminium edges can remove paint and dirt, albeit with a fair bit of wear to the scraper edge.
===Plastic==Plastics vary significantly in hardness, and are softer than metals. Sometimes a thin softer plastic finish on a hard surface makes its softness non-obvious - non-stick cookware is an example. Plastics also frequently need to retain their shine to look good. For these reasons only the softest of scraper material should be used occasionally on plastic (eg wood & fingernails) with detergents & other chemical cleaning methods much preferred. Clear plastics should not be scraped at all, just one scraping session can ruin their appearance.
===Aluminium==Aluminium is a fairly soft material. It tends to become pitted in use, and loss of shine on such surfaces is a non-issue.
====Linished===Linished aluminium has very shallow scratch marks in precise alignment, and rearranging the pattern ruins the visual effect. Such decorative surfaces should not be scraped. If there is no other option for a one off situation, scraping should at least be done in accurate alignment with the existing linish lines. A straight guide edge can be used to help ensure aligned scraping.
====Polished====Polished aluminium should not be scraped at all. Any scraping can be expected to visibly affect the surface. Chemical methods should be used. In principle aluminium can be refinished after scraping, but such refinishing isn't normally worthwhile.
===Stainless steel==May be scraped with aluminium or copper, or softer plastic scrapers. Scraping with steel is ok where a fine finish isn't needed, but it ruins the finish on stainless steel splashbacks, polished cutlery etc. Copper scourers are a good general purpose cleaning scraper for steel.
===Plastic coated sinks==The surface is soft and should never be scraped. Chemical methods are available for all the usual typers of muck. See [[Cleaning Sinks]].
==Scraper Materials= ===Steel scraper==* tough * popular * good where a fine surface finish doesnt matter * available in various blade shapes for removing paint from wood. * 5.5 mohs
===Iron wool==* tends to cause rust staining where stored * splinters are a problem * too hard for almost all modern surfaces * 4-5 mohs
===Stainless steel scourer==* too hard for most modern surfaces * too weak a structure to get much pressure on the edges * 5.5 mohs
===copper scourer==* good for cleaning steel * can also be used for exfoliation * copper has some antibacterial effect * removes rust spots from steel * 3-3.5 mohs
===Plastic scourer=* The softest of all scrapers. * Useful for general purpose cleaning
===finger nail==* 2.5 mohs, a fairly soft scraper * always to hand!
===plastic scraper==* soft scraper * removes weaker/softer forms of dirt * always to hand: a cut edge on some plastic kitchen waste works if you run out
===Aluminium scraper==* Small pieces of scrap sheet aluminium are convenient * 2.5-3 mohs, softer than copper * Useful for surfaces that wont tolerate anything harder * the scraping edge wears quickly in use
==Scrapers available====Commercial== Putty knife
Blade scraper - large snapoff one, std stanley blade.
Plastic de-icer scraper - windscreen
Spoke/hook shave - no, wotsit called?
== hoc==Plastic: expired credit card, offcut of thermoplastic (eg from kitchen bin)
Aluminium: offcut of sheet material.
Ad hoc bladed scrapers are usually blade plus mole wrench, but these aren't recommended due to the ease of blade slippage and consequent damage or injury.
==Power scrapers=Power scrapers use a vibrating metal blade.
==See Also=* [[Special:Allpages|Wiki Contents]] * [[Special:Categories|Wiki Subject Categories]]
[[Category:Cleaning]] [[Category:Paint]] [[Category:Tools]]