The original raw material is parge, a mixture of sand and lime with a binder like hair, traditionally used for parging flues and underlining roof tiles to reduce drafts. Many additional ingredients are recorded, including stable urine, loam, soot, tallow, road scrapings, cheese, dung, blood and salt, the aim being to produce a viscous material slowly curing to something leather hard. If it cured too quickly it would be difficult to work up a complex pattern; if it cured too slowly the frost might catch it. Traditional mixes might be applied in two or three layers finished with a limewash sheltercoat (repeated layers may obscure the design); later pargeting often contains cement, sometimes in sufficiently high proportions for the ornamentation to appear harsh, with a greater risk of cracking.