HMG Heat and Waterproof Adhesive (also known as HMG or HMG adhesive) is a brand of cellulose nitrate adhesive manufactured by H Marcel Guest Ltd. It is one of the most popular cellulose nitrate adhesives used in conservation and restoration work, and is used on materials such as metal, wood, glass, and pottery.Шаблон:SfnШаблон:SfnШаблон:Sfn It is sometimes referred to as "the blue tube", in contrast to "the purple tube", the acrylic B72 Restoration Adhesive also manufactured by the company.Шаблон:Sfn
HMG was invented during World War II by the company's founder, Herbert Falder.Шаблон:Sfn Today it is broadly used, including by the British Museum and the York Archaeological Trust. In 1997, HMG was used to adhere pieces of the Anglo-SaxonPioneer helmet, which was found broken into between 100 and 200 fragments.Шаблон:SfnШаблон:Sfn Particularly fragile areas had their cracks injected with a solution of HMG diluted 50% with acetone, to consolidate them and prevent them from collapsing; holes made while cleaning away corrosion were likewise injected with pigmented HMG.Шаблон:SfnШаблон:Sfn Stronger areas, such as the sinister cheek guard, found in eighteen pieces, and the nasal, were joined directly with the adhesive.Шаблон:Sfn Finally, HMG was also used to adhere glass fibre matting on the inside of the helmet, strengthening weak joins and covering gaps, the latter to provide backing against which gapfill could be applied.Шаблон:SfnШаблон:Sfn
Technical properties
HMG is advertised with a Шаблон:Convertflash point, and a Шаблон:Convert temperature resistance.Шаблон:Sfn It is insoluble in water and soluble in acetone, and is composed of 70% amyl acetate solvent, 25% cellulose nitrate, approximately 5% of the plasticizer dibutyl phthalate,Шаблон:Sfn and a small amount of a phenolic resin leveling agent.Шаблон:Sfn The adhesive is touch dry in five minutes, and hard dry in ten.Шаблон:Sfn
