Cyclic ethers obtainable by the condensation of a trihydroxy alcohol with a di- or tri-hydroxy alcohol or an aliphatic ketone are used as solvents or softeners in the production or treatment of dopes, varnishes, plastic masses, moulding powders, films, foils, &c., containing lacquer bases, particularly natural and artificial resins and cellulose esters and ethers. The cyclic ethers containing free hydroxy groups may be esterified or etherified. They may be used in connection with cellulose derivatives of high ester or ether content, e.g. cellulose acetate of acetyl content of 52-6,25 per cent. Other known low, medium, or high boiling solvents and/or diluents may be present, as well as substances such as dyestuffs, pigments, fillers, or substances reducing flammability. In the production of films and foils from solutions containing the cyclic ethers other volatile liquids are normally present, particularly in evaporative processes. In wet processes, the cyclic ethers may be present in the solution, or in the coagulating or after-treatment bath, for example, in the manner described in Specifications 179,234, [Class 2 (ii), Cellulose &c.], 340,324, 340,325, 340,436, and 340,437. The solvents are also used in the treatment of films in processes involving absorption by the film of various liquid and solid materials, e.g. in processes for dyeing, printing, loading, mordanting, and delustring. The more volatile cyclic ethers, e.g. di-glycerine tri-ether, are preferably used for this purpose. The following examples are given. (1) Mono-methyl ether of di-glycerine di-ether, or the mono-acetate thereof, and benzene-alcohol are incorporated with acetone-soluble cellulose acetate. (2) A lacquer comprises cellulose acetate, polyvinyl acetate, di-glycerine tri-ether, acetone, alcohol, and benzene. (3) A lacquer comprises nitrocellulose, diphenylol - propane - formaldehyde resin, di-acetate of di-glycerine di-ether, triphenyl phosphate, acetone, butyl acetate, and alcohol. (4) A lacquer comprises cellulose acetate, diphenylol-propane-formaldehyde resin, dibutyl tartrate, acetone, dioxane, and di-acetate of di-glycerine di-ether. Cyclic ethers are obtained by condensing a tri-hydroxy alcohol with a di- or tri-hydroxy alcohol or an aliphatic ketone in the presence of a dehydrating agent, e.g. sulphuric acid, phosphoric acid, zinc chloride, benzene sulphonic acid, or calcium chloride. Glycerol will condense with itself to form a cyclic di-ether or tri-ether, which may be separated from the non-cyclic di- and poly-glycerines, and from one another, by distillation. Glycerol may be condensed also with glycols or aliphatic ketones, e.g. ethylene glycol, propylene glycol, 1, 2- or 2, 3-butylene glycol, iso-butylene glycol, and acetone. Cyclic ethers which still contain free hydroxy groups may be esterified or etherified, e.g. they may be methylated, ethylated, acetylated, lactylated, and formylated. The Provisional Specification refers also to the production and treatment of filaments, yarns, fabrics, and the like, and includes the use of cyclic ethers as solvents or softeners in spinning solutions for dry or wet spinning processes, and as additions to coagulating or after-treatment baths. The ethers may be used to reduce the tendency of fabrics to split, slip, or ladder, as is described in Specification 280,990, [Class 2 (ii), Cellulose &c.]; to improve the pliability and knotting properties of filaments or threads; to improve the extension of filaments and threads, e.g. by the shrinking process of Specification 389,823; to improve the tenacity of filaments &c. by stretching processes as in Specifications 277,089, 323,790, [both in Class 2 (ii), Cellulose &c.], and 370,430. The cyclic ethers may be present in sizes for textile materials, and may be used as solvents or softening agents in processes involving absorption of various liquid and solid substances as is described above in connection with films. A further application of the ethers is for relustring cellulose derivative fabrics or other materials which have been delustred, e.g. by the process of Specification 259,265, [Class 2 (ii), Cellulose &c.]. The cyclic ethers are those obtainable by the condensation of a tri-hydroxy alcohol with a di- or tri-hydroxy alcohol and/or an aldehyde or ketone, as well as their esterification or etherification products.ALSO:Cyclic ethers obtainable by the condensation of a trihydroxy alcohol with a di- or trihydroxy alcohol or an aliphatic ketone are used as solvents or softeners in the production of dopes, varnishes, &c. containing lacquer bases, particularly natural or artificial resins and cellulose esters and ethers. The cyclic ethers containing free hydroxy groups may be esterified or etherified. Other known low, medium or high-boiling solvents and/or diluents may be present, as well as substances such as dyestuffs, pigments, fillers, or substances reducing flammability. The following examples of lacquers are included, (1) cellulose acetate, polyvinyl acetate, diglycerine tri-ether, acetone, alcohol, and benzene; (2) nitrocellulose, diphenylol-propaneformaldehyde resin, di-acetate of di-glycerine di-ether, triphenyl phosphate, acetone, butyl acetate, and alcohol; (3) cellulose acetate, diphenylol-propane-formaldehyde resin, dibutyl tartrate, acetone, dioxane, and di-acetate of di-glycerine di-ether. The Provisional Specification refers to the use, as solvents or softeners for lacquer bases, of the cyclic condensation products obtainable from tri-hydroxy alcohols and di- or tri-hydroxy alcohols, aldehydes, or ketones, as well as their esterification and etherification products.ALSO:Cyclic ethers obtainable by the condensation of a tri-hydroxy alcohol with a di- or tri-hydroxy alcohol or an aliphatic ketone are used as solvents or softeners in the production or treatment of plastic masses, moulding powders, films, &c. containing lacquer bases, particularly natural and artificial resins and cellulose esters and ethers. The cyclic ethers containing free hydroxy groups may be esterified or etherified. Other known low, medium or high boiling solvents and/or diluents may be present, as well as substances such as dyestuffs, pigments fillers, or substances reducing flammability. The following example is included : Monomethyl ether of di-glycerine di-ether, or the mono-acetate thereof, and benzene-alcohol are incorporated with acetone-soluble cellulose acetate. Other specified cyclic ethers are di-glycerine tri-ether and di-acetate of di-glycerine di-ether. The Provisional Specification refers to the use, as solvents or softeners for lacquer bases, of the cyclic condensation product obtainable from tri-hydroxy alcohols with di- or tri-hydroxy alcohols, aldehydes or ketones, as well as their esterification and etherification products.