NL8100706A - PAINT REMOVERS. - Google Patents

Description

-1-

Reg.nr. 115.366 / Bnt / RB

t

Paint removers.

The invention relates to paint removers, in particular on an alkali basis.

When refinishing woodwork, it is often desirable to remove old layers of paint, either to provide a good base for new paint or to expose the underlying surface. Until now, a blow lamp has been used to soften the old paint, which is then removed with a scraper. However, this requires considerable dexterity, and even experienced house painters can blacken the underlying surface. This does not have to be a serious drawback when the surface has to be painted again, but when, for example, a cleaned wooden surface has to remain unpainted, shadings are hideous.

The amateur painter will therefore generally avoid a blow-lamp 15 and instead rely on chemical paint removers. Generally, such paint removers are applied to the painted surface, left for some time to soften the paint, then paint and remover are removed together with a scraper. Paint removers fall into two major categories: organic solvent based removers and aqueous alkaline removers.

Organic solvents are used as the basis for the first category of conventional removers, often together with an alkali. These are very effective but extremely unpleasant to use due to the presence of the solvent, and the (thin) nature of the composition, which results in 81 0070 6 i -2- dripping and running off.

Instead of the organic carrier, sheet has also been used more widely to form aqueous compositions, which usually contain {an alkali as the active paint removal ingredient. Here again, the thin nature of such compositions makes them uncomfortable to use and also the tendency of the composition to thin and run off vertical surfaces does not allow the active ingredient to remain in contact with the paint ji long enough to lead to efficient disposal. j l 10 A recent improvement in aqueous removers has recently been achieved by including a gelling agent and a filler such as lime in the composition to give a paste-like consistency. This makes application of the remover to a painted surface easier and eliminates the problem of dripping while removing the remover and softened paint from flat surfaces is greatly facilitated since the paint is practically from it; surface can be sealed with a paint scraper. However, the combined remover / paint layer does not have lateral cohesion, so it is necessary to remove hair by passing the scraper over the entire area between the layer and the underlying surface. This does not present any difficulty on flat surfaces, but on compound curves, such as chair legs or cornices, removal is not easy with a scraper. !

It has now been found that remarkably good paint removal can be obtained, especially on surfaces that carry oil-based paint, with a remover that forms a peelable skin over the painted surface. The alkali is contacted with the paint to be removed, which is then softened sufficiently, and subsequent removal of the remover / paint layer is greatly facilitated, especially in complex shapes.

According to one aspect of the invention there is therefore provided: a spreadable aqueous paint removal composition consisting of an alkali in such an amount that the composition is able to remove paint together with one or more skin-promoting promoter components, so that when the composition is applied as a layer over a painted surface from which the paint is to be removed, it forms a peelable skin over the surface which has sufficient tear strength to be separated and removed from the underlying surface and an adhesive strength sufficient to be separated from and removed from the underlying surface. surface paint, softened by contact with the composition. The composition according to the invention is layered over the surface to be cleaned and forms a peelable skin over it. The peelable skin has a tear strength sufficient to be separated from the underlying surface as an integral gel. The composition layer thus develops a lateral strength, which makes it possible to remove hair like intact skin. However, the lateral strength does not have to be high to obtain the advantages according to the invention, and the skin does not, for example, have to have lateral elastic properties.

The manner in which the strippability property of the skin formed using the composition of the invention can be provided can take a number of forms. According to a first embodiment, the composition may consist of fibrous material as a skin enhancement promoting component, which holds the aqueous alkaline composition together to form a peelable skin. Such compositions generally contain a gelling agent as a skin formation promoting component in addition to the fiber. According to a modification of this embodiment, the composition may contain a filler as an additional skin-promoting promoter to thicken the composition and increase the absorbent properties of the peelable skin.

In another embodiment, no fibrous material is used, but the strippability property is obtained by thickening the composition with filler and by using a certain combination of gelling agents.

81 00 70 6 -k-

Thus, according to the broadest aspect, the first embodiment of the above invention is a spreading; bare aqueous composition containing an alkali and a suitable amount of fibrous material, which composition 5 is alkaline enough to remove paint. j

The alkali is most suitably an alkali metal hydroxide since it gives a highly alkaline composition and is readily available and inexpensive. Sodium and potassium hydroxide are preferred. However, it is possible to use other alkalis

.... I

Use 10 with a pH m aqueous solution of more than 10, such as | alkali metal silicates, for example sodium metasilicate, and phosphates for example trisodium phosphate. Other highly alkaline materials, preferably with a pH of more than 12 and most preferably more than 13, are well known in the art and can be used in the composition of the invention. Sodium hydroxide is generally most preferred for use as the | alkali, as other compounds are more expensive and milder or slower in action. If desired, sodium hydroxide can be provided by using a mixture of sodium; Carbonate and calcium hydroxide. i

In some applications, such as where a hazard may exist exist for staining the surface under the paint, it may be desirable to choose a milder alkali, in which case one could use trisodium phosphate.

The concentration of alkali in the composition would be chosen according to known criteria, and it is believed that this choice is within the competence of one skilled in the art. When using sodium hydroxide as the alkali, it is possible to use concentrations of 25% by weight. or more. However, it is preferable to use no more than 12 / ¾ sodium hydroxide; since this does not conflict with the rules set up in England for handling poisons. The lower concentration limit is determined by the paint removal job for which the composition is intended, and can '35 minimum 1? or even less. The usual concentration for sodium hydroxide is from 3-12?, Preferably 3-7 ?.

8 1 00 70 6 -5-

Within these preferred ranges, the particular concentration is chosen in view of the removal rate required, relative to the effect on the cost of the removal agent.

With other alkalis, preferred concentrations will be assessed on such a basis. Potassium hydroxide can be used in concentrations up to Y% without special treatment being required under the English poison rules, so that this alkali may be preferable when a higher concentration is needed. One such concentration step for the alkali salts mentioned above is from 30% to 0%.

The compositions preferably contain a gelling agent, as an additional skin-promoting promoter, and this may be a natural or synthetic water-soluble polymer. Such gelling agents are well known in the art.

Examples of suitable agents are polyacrylic acid and its esters, starch, natural gums such as gum tragacanth or;

British gum, cellulose ethers, hydroxyethyl cellulose, xanthan gums and synthetic clays such as montmorillonite clays. Preferred gelling agents are the xanthan gums and 20 synthetic clays. An example of a commercially available xanthan gum is Kelzan, a high molecular natural ** polysaccharide produced in a pure culture fermentation process by the microorganism Xanthomonas campestris and available from Kelco, a division of Merck & Co.Ine .. A 25 preferred synthetic clay is Laponite, which is a synthetic hectorite, a magnesium silicate, containing lithium and fluorine or hydroxy groups in a layered structure. This clay is supplied by Laporte Industries Limited.

The amount of gelling agent used is selected based on the thickness required for the composition in view of the properties of a particular gelling agent used. It is not possible to indicate preferred ranges for gelling agents in general, since different agents are used at different concentrations to achieve the same degree of gelling. It is believed, however, that it is within the competence of one skilled in the art to choose an appropriate gelling agent concentration. It can only be said by way of illustration that it is unlikely to be

i I

gelling agent will be used in concentrations greater than 10 wt%, while a suitable lower limit is 0.156. Further examples will be given below, further illustrating suitable concentrations of gelling agents in certain compositions.

The fibrous material in the first embodiment j! of the invention functions while holding the gelled j; t l 10 layer of composition on the painted surface, thus making ί, "" the layer peelable. One can find a wide variety of "organic and inorganic" natural and synthetic fibers; use to contribute to the strippability of the composition, provided that the fiber does not deteriorate due to the other components of the composition at the concentrations used. The fibers can be, for example, ground paper, paper flakes, paper punches, wool, textile fibers, asbestos, wood pulp or plastic material fiber such as viscose fiber or ground synthetic leather. These fiber forms are relatively inexpensive there; They are derived from waste materials, and ground paper is in particular an inexpensive source of fiber and is therefore preferred,

The fiber used is preferably in the form of.

relatively short individual fibers, meaning i ...

ί 25 that the fibers are no longer than 10 mm. A preferred form of haphazardly ground paper fiber has fibers with lengths of at most; 2 mm.

The fiber content of the composition is chosen so that the desired degree of strippability is obtained! 30 in conjunction with the selected gelling agent. Typically, the fiber will form no more than 25 weight percent of the composition, and generally, compositions will contain no more than 15/6 fiber and preferably no more than 12 # fiber. Too much fiber can cause the composition to become too thick to be applied to the surface to be stripped. A preferred bottom; limit is approximately% fiber, while excellent strippability; 81 00 70 6 -7- is obtained at fiber contents of not less than 8%.

The fiber-containing compositions of the invention may also contain a filler, that is, a solid particulate component which is substantially inert to the other components of the composition and to paint, spring as an additional skin-promoting component. This filler resists the mass of the composition and increases its thickness. In use, the filler additionally absorbs the liquefied: paint, which is attacked by the alkali, and helps to run away; 10. Suitable fillers that can be used; include powdered lime, clay, fly ash, vermiculite and sawdust. Of these, powdered lime is most preferred for use in the invention.

The filler must not be used at a concentration, the composition becoming too thick to be spread, and it will be appreciated that the amount of filler that can be used to give a spreadable composition is affected by the amount of fiber fiber . When filler is present, the amount of fiber can generally decrease. It has been found to be advantageous to use up to 6b% filler together with up to 20% fiber and effective compositions can be obtained with filler and fiber even if the amount of fiber is below 3%, the preferred lower limit being fiber content in the absence of filler. It has been found that the filler to fiber ratio is most suitably in a range of 6: 1 to 1: 1 and most preferably in the range of U: 1.

It has also been found that peelable compositions can be obtained without the use of fiber using filler together with a specific combination of gelling agents. According to another embodiment, the invention therefore provides a spreadable composition consisting of an alkali, filler, a xanthan gum and a synthetic hectorite clay, each composition being sufficiently alkaline to allow paint stripping.

The alkali used in this embodiment is selected according to the criteria set forth above and uses rS & r ·.

81 00 70 6 -8- at the concentrations proposed above.

The filler can be selected from the materials previously mentioned, but is generally used in '; somewhat higher concentrations. The filler will generally be present in an amount of at least 25% by weight, preferably at most 75% by weight. Most preferably, the amount of filler is in a range of 50 - 70 # in the fiber-free compositions. The. 1 Actual amount of filler used is determined by the rheological properties of the compositions, which in turn are determined by the nature and concentrations of the gelling agent. In qualitative terms, the amount of filler 'Ί should not be so low that it leads to a slurry, which would tend to run off a surface to be stripped, but should be present in enough filler that the composition is not easily | 15 on a surface, can be spread. j

In a preferred embodiment, the composition is thixotropic, but even when exhibited, it must, of course, be sufficiently mobile to allow spreading upon processing.

It has been found that a certain combination of gelling agents is required to obtain strippability in a composition containing filler and no fiber. The xanthan gum is preferably Kelzan gum, and the clay is preferably Laponite. These gelling agents are preferably used in concentrates; 25 ratios of 0.2 - k% Kelzan and 0 - 2.0 # Laponite, the ratio of Kelzan to Laponite being in the range of 5: 1 to 1: 1.

Both types of compositions of the invention, whether they contain this fiber or not, may also include other standard ingredients for paint removal compositions, such as wetting agents, dyes, preservatives and water-miscible organic solvents. All these additives must, of course, be compatible with the other ingredients, and in particular with the alkalinity of the compositions, and must also be miscible with water The choice of these, conventional ingredients and suitable concentrations are 81 00 70 6-9 within the competence of the expert.

By including a bleaching agent in each of the compositions of the invention, it is possible to provide a paint remover which simultaneously bleaches the underlying surface. Conventional bleaching agents such as sodium chlorate or hydrogen peroxide can be used, typically at a concentration of 0-10% by weight of the composition.

In use, the compositions of the invention are applied to a painted surface typically as a layer of up to 3 mm thick. It is suitable to spread the composition on the surface with a trowel or the like spreader. The composition is then left to sit until the paint has softened. This will typically take 1 - 6 hours 15, although longer contact times may be desirable when many layers of paint have to be removed. When the composition layer dries out during this time, it can be sprayed with water to moisten it and ensure maximum contact of the alkali with the paint.

The layer of composition is then removed as a peelable skin using a scraper or similar tool, although actual surface scraping will not be necessary. The skin is lifted off the surface along with the softened paint, and complex shapes can be easily peeled off without scratching the paint from any nook or cranny.

According to a second aspect, the invention includes a method for stripping a paint layer from an underlying surface, wherein an effective amount of a composition, as described above, is applied to the paint layer to form the peelable skin together with the paint, which has been plasticized by the action of the composition, after which the formed skin is lifted and stripped from the underlying surface to remove its paint.

The compositions of the invention have been described above in ready-to-use form. However, it will be appreciated that the compositions of the invention can be produced for distribution and sale in dry powder form. | In another aspect, the invention therefore provides a dry powder form composition which, when mixed with water, can form a spreadable aqueous paint stripper composition as described above. j

The dry powder composition can be the same as the spreadable aqueous composition, except for the incorporation of water into it. However, since at least some of the alkali materials described above cannot be handled appropriately in dry form, it is preferable to formulate the dry composition with a mixture of calcium hydroxide (lime) and an alkali salt, the anion of which is insoluble salt forms with calcium. The ingredients of such a mixture, when mixed with water, will provide an alkali metal hydroxide, eg sodium hydroxide, but in dry form they will be handled more easily than the corresponding alkali metal hydroxide.

Preferably, the alkali salt and the calcium hydroxide are used in substantially stoichiometric amounts, the percentage of each in the dry composition being such as to provide a corresponding percentage of the alkali metal hydroxide.

. . ,,,, f I

m in accordance with the description above, preferably

3-12% by weight of hydroxide. I

Since the dry powder is particularly useful as a do-it-yourself product, it may be formulated with an increased amount of filler (where present) to facilitate mixing with water, if necessary. For example, when a filler and a fiber are used simultaneously, the ratio of! Filler to fiber may be up to about Ti1.

The invention will now be illustrated in a non-limiting manner with the following examples, which show aspects of the invention in more detail.

Example I; Paint remover containing fiber and filler 35 A composition is prepared from the following ingredients: 1 81 00 70 6 -11-

Gram Kelzan 26.2 Sodium Hydroxide Solution (^ 8 wt%) 10¾, 6! Ground paper ιοί », 6 5 Lime 10¾» 6 Water 66o, o • 1000.0 Example II: Paint remover containing fiber 10 A composition is prepared. the following ingredients: Gram Kelzan 26.2 Laponite S 10.7 15 Sodium hydroxide solution (1 * 6 pounds) 10¾.6 Ground paper 10¾.6 Water 753.9 1000.0 20 Example III: Paint remover containing filler contains A composition is prepared from the following ingredients: Gram Kelzan 10.5 25 Laponite S Sodium hydroxide solution (U6 found #) 83.3 Lime 6ko, o Water 261.9 1000.0 30 Example IV: Paint remover containing filler and fiber

A thixotrope is prepared. composition of the following ingredients: 81 00 70 6 -12- iS £ Kèlzan 1.00 II Laponite S 0.50 I Sodium hydroxide solution (1 * 6% by weight) 10.1 * 5 i 5 Lime 3 **, 83 Ground paper from 1.56 mm TM Water. 1 * 5.77 100.01 Example V: Paint verifier containing filler and fiber 10 A composition is prepared from the following ingredients: Kelzan 0.871 15 Laponite S 0.1 * 35 Sodium hydroxide solution (1 * 6%) ,%) 10.1 * 5 Lime 37.31 3.125 mm paper flakes 8.71 Water 1 * 2.226 20 100.00 Example VI: Paint remover containing filler and fiber A composition is prepared from the following ingredients: Gev. % 25 Kelzan 2.6 Sodium Hydroxide 5.0 Crushed 3.125 mm Paper 10.5 • 0.053 mm Sawdust 10.5 Water 71.1 * 30 Example VII: Paint Convergent Containing Filler and Fiber Preparation is Prepared the following ingredients:% by weight Kelzan 2.6 35 Sodium Hydroxide 5.0 0.032 mm Vermiculite 10.5 8100706

-13- Density% 3 * 125 mm milled paper 10.5 Water 71, U Example VIII: Paint remover. containing filler and fiber 5 A composition is prepared from the following ingredients:% by weight Kelzan 2.0 Laponite 0.8 10 Sodium hydroxide 5.0 Lime 21.0 Vermucilite of 0.032 mm 10.5 Ground paper of 1.56 mm 5.0 Water 55.7 Example IX: Paint Removal Containing Filler and Fiber A composition is prepared from the following ingredients:% by weight Kelzan 1.0 - 20 Laponite 0.5 Potassium Hydroxide 5, 0 Lime 35.0 Paper flakes of 3.125 mm 7.5 Water 51.0 Example X: Paint verifier containing filler and fiber A composition is prepared from the following entry <ty Λ * -.

V; f -'IJ * 'm φ. «.R-p dients:

Found%. Kelzan 2.6 Sodium hydroxide 5.0 Lime 10.5 Viscose fiber 10.5 Water 71. EXAMPLE XI: Removal remover containing filler and fiber. A composition is prepared from ingredients: the following ingredients:

81 00 70 6 -ii * - Gqv.% Water 58.2 Lime 15.7 6.25 mm paper flakes 15.7 Sodium hydroxide (U8 wt%) 100.0

The pH of the compositions of Examples I - XI are within the range of 13 - 1¾.

Example XII: Paint remover containing filler and fiber 10 A composition is prepared from the following ingredients: Part% Kelzan 1.0 Laponite S 0.5 15 Sodium Phosphate 10.0 Lime 3M 1.56 mm milled paper 7.5. Water 1 * 6.2 The pH of the composition is 11.8. Example XIII: Paint remover. containing filler and fiber A composition is prepared from the following ingredients:% by weight Kelzan 1.0 25 Laponite S 0.5 Sodium metasilicate 10.0 Lime 3M Paper flakes 3.125 mm 7.5 'Water 1 * 6.2 30 The pH of the composition is 12.7. The invention will now be illustrated in a non-limiting manner with the following examples, which show the results obtained in. stripping paint with a known composition and with the compositions according to the invention.

81 00 70 6

Trial results

Method

Paint removers are tested for their effectiveness in removing four coats of oil-based paint from a wooden surface. The painted surface is divided into test areas of 15 x 10 cm using pieces of self-adhesive plastic tape. A paint removal composition to be tested is applied to a test area with a trowel or spatula to a thickness of about 3 µm estimated on the eye. Men. leave the composition in contact with the test area for a time and then remove with a spatula. The nature of the composition at the time of removal, the ease of removal and the amount of stripped paint are determined. The results are set out below.

Results

To provide a comparison, a known paint remover is also being tested. The composition of this is:

Found%

Gelling agent (Viscalex HV30 - an acrylic copolymer emulsion from Allied Colloids Ltd) 3.0 Sodium hydroxide M Lime 66.5 Anti-foaming agent 0.2 Water 26.2

In individual experiments, this known composition is left in contact with the experimental areas for 2/3 hours and 2 hours. The results are shown in the following Table A:

Table A

Composition Contact duration (hours) Nature during stripping removal to be painted According to the state of the art 2/3 paste B0% According to the state of the art 2 paste 100 £ -16-

In any case, the paint removal composition is removed as a paste. It shows no cohesion and is not peelable. Consequently, it was necessary the. scrape paste off the surface to be cleaned which is a dirty and time consuming job. After 2/3 hours, a removal of 8058 has been achieved, ie all four layers of paint have been removed over 80% of the test area. After 2 hours 10058 removal is obtained and all four layers of paint are scraped from the test area.

The results obtained when testing compositions of the invention are set forth in the following Table B, in which the compositions are identified by referring to the example in which the recipe details are given.

i

Table B ί

Composition Contact duration (hours) Nature during removal Stripped paint 1 1 peelable skin 10058 2 1 Vt 10058 3 1 ff 10058 1 »1 ff 10058 k 2/3 ff 1005» 5 1 ff 10058 6 1 ff 10058 7 1 ff 10058 8 1 ff 10058 9 1 ff 10058 10 1 ff 10058 11 10 dry peelable skin 100J8 12 5 peelable skin * 13 5 tsp ** 30 *

One layer completely removed, a second layer removable with scraping.

** Approximately 9058 with scraping removal.

β 1 00 70 6 5 -17- 5 -17- ίο 15 20 25 30

In any case, the tested composition forms a peelable skin, which can be removed from the test area at one time along with the paint which has been fattened by the alkali. In the compositions containing sodium hydroxide or potassium hydroxide! 1005% removal is obtained without scraping. It was only necessary to wash off the stripped area after removing the skin leaving a clean stripped wood surface. The compositions containing trisodium phosphate and sodium metasilicate are intended to be milder so that they can be used on fine workpieces or where selective removal of only top coats of paint is required. Thus, in the tests complete removal of all four layers of paint is not achieved with these alkalis, but the compositions do demonstrate the advantage of the invention in that they form a peelable skin which facilitates the cleaning operation.

Example XIV: Paint remover containing fiber and filler in dry powder form

A dry powder composition is prepared from the following ingredients:

Parts

Sodium carbonate 5.0

Calcium hydroxide 3.5

Lime 3M

Paper granules of 3.125 mm 5.0

Kelzan 0.75

Laponite S. 0.38

This composition is suitable for transport, storage and sale in dry powder form and when mixed with water up to 100 wt. parts it forms a spreadable aqueous paint remover composition, which forms a peelable skin in use and provides 00% paint removal without scraping, as with the compositions containing sodium hydroxide.

81 00 70 6 -18-

Example XV: Paint remover. containing fiber and filler, in dry powder form

The compositions described in Examples XII and XIII are formulated without water in dry powder form. If required for use, the compositions are mixed with water up to 100% by weight and then behave as described above.

1 00 70 6

Claims (22)

1. Spreadable aqueous paint remover composition containing an alkali in an amount such that the composition is able to remove paint, characterized in that the composition further comprises one or more skin-forming promoting components, whereby when the composition is applied as a layer over a painted surface to be cleaned, forming a peelable skin over the surface which has a tear strength sufficient to be able to handle it. 10 separating and removing the underlying surface and an adhesive strength sufficient to separate and remove hair from the underlying surface paint plasticized by contact with the composition. 2. A composition according to claim 1, characterized in that it has a pH of at least about 12. Composition according to claim 1 or 2, characterized in that. that the alkali is an alkali metal hydroxide. The composition according to any one of the preceding claims, characterized in that it contains 3-12% by weight of sodium hydroxide. Composition according to any one of the preceding claims, characterized in that the composition comprises a fibrous material as a skin-promoting promoter, 6. A composition according to any one of the preceding claims, characterized in that it comprises a gelling agent as an additional skin formation promoting component. Composition according to claim 6, characterized in. that the gelling agent is polyacrylic acid or an ester thereof, a starch, a natural gum, a cellulose ether, a hydroxyethyl cellulose, a xanthan gum or a synthetic clay. Composition according to claim 7, characterized in that the xanthan gum is obtained in a pure culture fermentation process by the microorganism Xanthomonas camnestris. 9. A composition according to any one of claims 6-8, characterized in that it contains about 0.1-10% gelling agent. Composition according to any one of claims 6-9, 81 00 70 6 -20- characterized in that the fibrous material consists of ground paper, paper flakes, paper sponges, wool, textile fibers, asbestos, sawdust or a fiber of plastic material . 11. A composition according to any one of claims 5-10 5 characterized in that the fibrous material consists of fibers no longer than about 10 mm. 12. A composition according to any one of claims 5-11, characterized in that it contains about 5-15 wt. Fibrous material. 13. A composition according to any one of claims 1-11, characterized in that it comprises a substantially inert particulate filler as an additional skin-promoting promoter. lit. Composition according to claim 13, characterized in that the filler is powdered lime, clay, fly ash, vermiculite or sawdust. Composition according to claim 13 or ih, characterized in that it contains up to about 6U by weight of $ 5 filler, and wherein a fibrous material is also present up to about 20 wt.% fibrous material, the filler to fibrous weight by weight ratio being in the range of 6: 1 to 1: 1. 16. Composition according to any one of claims 1 - * or any of claims 6-9, 13 or 1U, insofar as dependent on any one of claims 1-1 *, characterized in that the composition. ; 25 contains a filler, a xanthan gum and a synthetic hectorite clay as said skin-promoting promoter components. A composition according to claim 16, characterized in that it contains 25-75% filler. 18. A composition according to claim 16 or 17, characterized in. that this is thixotropic, A composition according to any one of claims 16-18, characterized in that it contains 0.2-h wt. Xanthan gum and up to 2 wt. : 1 to 1: 1. 81 00 70 6 -21- 20. Method for stripping a paint layer from an underlying surface, applying an effective amount of a spreadable aqueous paint remover composition to the paint layer and the remover and removing the softened layer, characterized in that a composition according to any one of the preceding claims, which composition is allowed to form a peelable skin together with the paint, which has been plasticized by the action of the composition, and lightens and dries the formed skin from the underlying surface to remove the paint thereof . 21. A composition according to any one of the preceding claims, characterized in that it is in a dry powder form which, when mixed with water, can form a spreadable aqueous paint removal composition according to any one of the preceding claims 1 - 19. 22. A composition according to claim 21, characterized in that it comprises calcium hydroxide and an alkali salt, the anion of the alkali salt being one which forms a water-insoluble salt with calcium to provide alkali in such a form. amount that the aqueous stripper is able to remove paint along with 44n or more skin-promoting promoter components, so that when the aqueous stripper is applied as a layer over a painted surface to be cleaned, it over the surface peelable skin that tends to have a tear sufficient to handle it. separating and removing the underlying surface and an adhesive strength sufficient to separate and remove hair from the underlying surface paint which has been plasticized by contact with the composition. Composition according to claim 22, characterized in that the metal salt is sodium carbonate. 2k. Composition according to claim 22 or 23, characterized in that the calcium hydroxide and the alkali salt together provide 3 to 12% by weight of alkali hydroxide in the aqueous remover. A composition according to any one of claims 22-2U, characterized in that the ingredients and / or their percentages and / or 81 00 70 6 '22' are their amounts as specified in the preceding claims. 1 l A composition according to any one of claims 21 or 22, substantially as described above in Examples XIV or XV. A spreadable aqueous paint remover, characterized in that it consists of a composition according to any one of claims 22 to 26 mixed with water. »