Wool or wool-containing textile material is treated to reduce its shrinking tendencies by pretreating the material with an alkaline solution of a peroxy compound containing the group -O-O and then impregnating the material with a solution or dispersion of a curable aminoplast. Examples of peroxy compounds which may be employed are hydrogen peroxide, sodium, potassium, and other alkalimetal peroxides; organic peroxides such as benzoyl peroxide, acetyl peroxide, lauroyl peroxide, succinyl peroxide, and tertiary-butyl hydroperoxide; per-salts such as the alkali metal and ammonium perphosphates, persulphonates, perborates and percarbonates; organic peracids such as peracetic and perbenzoic acids and the alkali-metal and ammonium salts of such acids, and organic and organometallic salts of hydrogen peroxide such as tetramethyl, tetraethyl and other tetraalkyl ammonium peroxides and triethyl tin peroxide. In general the peroxy compound is used in an amount chemically equivalent (oxidation equivalency) to at least about 0.05 per cent by weight of hydrogen peroxide based on the weight of the alkaline solution and preferably the concentration of the peroxy compound on the above basis is at least 0.5-0.6 per cent. The preferred peroxy compound is hydrogen peroxide and the preferred concentration is 0.5-2.5 per cent by weight of an aqueous alkaline solution. Alternatively the solvent may be an alcohol such as ethanol, propanol, or butanol, or a mixture of water and an alcohol. The alkalinity of the bath may be such that the pH value is about 8-12, particularly 9-11, and the necessary degree of alkalinity may be imparted to the bath by the addition of alkali metal hydroxides, acetates, carbonates and bicarbonates, ammonium hydroxide, amines such as triethanolamine, borax, guanidine carbonate, disodium phosphate, sodium silicates, or soap. The time of treatment of the wool-containing textile with the preconditioning solution is usually about 15-30 minutes and the temperature of the solution is usually about 110-160 DEG F., preferably about 125 DEG F. After treating the textile material with the alkaline solution of the peroxy compound, it is washed, for example with water alone or with water followed by dilute acid and a final water wash to remove the excess alkali. The pretreatment is applicable to both undyed and dyed wool-containing textiles, and the pretreated material may be dyed without undoing the effects of the peroxy treatment. The heat-curable aminoplasts used, more particularly heat-curable amino-aldehyde reaction products, are preferably those which are at least partly soluble in water. For example, the aminoplast may be a substantially monomeric reaction product or a relatively low molecular weight intermediate reaction product of an aldehyde, e.g. formaldehyde, with a compound containing two or more -NH2 groups, e.g. urea, melamine, or mixtures of urea and melamine. Alkylated (e.g. methylated, ethylated, propylated, or butylated) reaction products of an amino-compound and an aldehyde may be employed, e.g. a methanol- or other alkanol-reacted urea-formaldehyde or melamine-formaldehyde, reaction product. It is preferred to use methylated trimethylol melamine. The heat-curable aminoplast usually constitutes about 3 to 15 per cent by weight of the liquid finishing composition and may be dissolved or dispersed in water or a mixture of water and an alcohol such as ethyl alcohol. The curing of the aminoplast may be speeded up by the addition to the finishing composition of 0.5-5 per cent by weight (based on the aminoplast) of a catalyst such as oxalic acid, acetic acid, phosphoric acid, diammonium hydrogen phosphate, diammonium ethyl phosphate, diammonium phthalate, ammonium chloride, ammonium silicofluoride or zinc chloride. The pick-up of the liquid finishing composition by the material may be such that the finished material contains from about 1 to 8 per cent, particularly about 3-5 per cent, of the cured aminoplast, based on the weight of the dry material. In some cases the percentage may be as high as 15 per cent. The wet, impregnated material is finally dried and cured. The curing temperature may be about 250 DEG to about 400 DEG F., applied for a few seconds to a few minutes. The material may be unwoven wool yarns, or fabrics composed entirely of wool or of mixtures of wool with cotton, silk, any of the rayons, nylon, polyacrylonitrile, or with fibres produced from casein or from soya beans. In an example, undyed all-wool flannel is immersed for 30 minutes in an aqueous solution at a temperature of about 125 DEG F. and pH about 10 containing sodium silicate and 0.6 per cent by weight of hydrogen peroxide. The treated flannel is removed from the bath, rinsed in water, padded and dried in a frame for 10 minutes of 240 DEG F. while held to its original size. The flannel is then immersed for one minute in an aqueous solution containing about 5 per cent by weight of trimethylol melamine (in which an average of two methylol groups have been methylated), 0.155 per cent of diammonium hydrogen phosphate, and 0.03 per cent of a wetting agent (dioctyl sodium sulpho-succinate). The flannel is then padded to a wet pick-up of about 100 per cent by weight of the dry flannel, framed to size and heated for 9 minutes at 290 DEG F. After cooling to room temperature the treated flannel is soaped. Other examples are given, in some of which sodium perborate is used instead of hydrogen peroxide, in others the nature of the alkali of the preconditioning bath is varied and in others a substantially unpolymerized reaction product of formaldehyde and urea is used instead of methylated trimethylol melamine for the second treatment bath. In a modification, the aminoplast is cationic, is in the form of an aqueous colloidal solution and may be the product obtained by reacting, in an acid medium, an aminotriazine, e.g. melamine, ammeline, guanamine, or acetoguanamine and an aldehyde such as formaldehyde. Alternatively the cationic aminoplast may be the reaction product in an acid medium of ingredients comprising (1) an aminotriazine, e.g. melamine; (2) urea, or a monohydric alcohol such as methanol or ethanol, or both urea and an alcohol; and (3) an aldehyde such as formaldehyde. Ordinarily an aqueous colloidal solution of a cationic partially polymerized reaction product of melamine and formaldehyde is used, a 6 per cent colloidal solution of the product having a pH of about 0.25-4.0. Methods for preparing suitable colloidal solutions of aminoplasts are described in U.S. Specifications 2,345,543, 2,356,718, 2,394,009, 2,417,014 and 2,423,428. The concentration of the colloidal aminoplast may be about 1-20 (usually 3-12) per cent by weight of the aqueous finishing composition which may also contain an alcohol such as ethanol or glycerol. The use of cationic instead of non-cationic aminoplasts permits the employment of lower drying and curing temperatures. Examples are given of treatments employing cationic aminoplasts. Specifications 553,923, 564,958, 569,730 and 579,584 and U.S.A. Specification 2,395,791 and U.S.A. Reissue Specification 22566 also are referred to. Specifications 623,355, 623,361 and 623,362, [all in Group IV (a)], also are referred to.