Pewter

Pewter is a malleable metal alloy, traditionally 85-99% tin, with the remainder consisting of copper, antimony, bismuth and lead. Copper and antimony act as hardeners while lead is common in the lower grades of pewter, which have a bluish tint. It has a low melting point, around 170–230 °C, depending on the exact mixture of metals. The word pewter is probably a variation of the word spelter, a colloquial name for zinc.Today only leadless pewters are in use.

History
Pewter was first used around the beginning of the Bronze Age in the Near East. The earliest piece of pewter found is from an Egyptian tomb from 1450 BC.

Cleaning
1.Fresh common horsetail plant(Equisetum Arvense) can be used for cleaning of light corrosion.
 * Mechanical

2.Water and precipitated chalk paste can be used too.

1.Diluted hydrochloric acid
 * Chemical

5 % HCl

0,5% hexamethylene tetramine

Immerse object in solution,when it is clean rinse well with sodium bicarbonate solution(3 %),and after that with water. Do not use on archaeology objects!

2.Trisodium Phosphate Solution

150 gms trisodium phosphate

1 lit water

Immerse objects in boiling solution,after 10 minutes rinse well and repeat if needs.


 * Electrochemical

Electrolytic cleaning

2-5 % Na2CO3 solution

stainless steel anode

current density 1A/dm2,6-12 v

Object connected to negative terminal of current source must be immersed in solution, anode must be immersed before.


 * Ultrasonic


 * Laser

Clearcoats

 * Paraloid B 72
 * Paraloid B 67
 * Paraloid B 44
 * Paraloid B 48 N

Waxes

 * Renaissance Wax
 * Cosmolloid 80 H
 * Dinitrol 4010
 * DIY mixtures

Combinations

 * basecoat Paraloid B 72 + topcoat Renaissance Wax etc.