A METHOD FOR THE PREVENTION OR REMOVAL OF GROWTH OF ALGAE AND LICHENS ON POROUS BUILDING MATERIALS

Abstract: Porous building materials are protected against growth of algae and lichens by treating first with a solution of a copper salt and then with a soap solution.

Description: A Method for the Prevention or Removal of Growth of Algae and Lichens on Porous ' Building Materials- Technical Field The present invention relates to a method for the pre- vention of growth of algae and lichens on porous build¬ ing materials such as wood, concrete, tile and eternite by first treating the building materials with an aque¬ ous solution of copper salt and then with a binder which binds copper compounds in the building materials. Background Art It is well known that copper compounds are toxic to algae and lichens and can be used to protect building materials against growth of algae and lichens- Thus, it is known to impregnate porous building materials with copper sulphate and to impregnate building materials first with a soluble copper salt and then with a binder which precipitates insoluble or sparingly soluble cop¬ per compounds in the building materials . However, the effect of the known methods is poor or relatively short-lived and for that reason there is a need for methods which can give a prolonged effect. Disclosure of Invention It has now turned out that a desirable prolonged effect is obtained by the method according to the invention the characteristic feature of which is that a soap solution is used as the binder. It is assumed that hereby is caused a formation of copper compounds of such moderate solubility that"the toxic effect maintains for a long period of time as distinct from the situation when in- soluble copper compounds are precipitated. The method of the invention is efficient when the treat¬ ment solutions are applied by simple coating, and it is therefore applicable to existing structures but may of course also be carried out by immersion of the indivi^ dual pieces of building material in the treatment solu¬ tions prior to the use of the materials. The method does not result in formation of dark coloured copper compounds and is therefore also applicable to light coloured building materials such as concrete surfaces . When the method is used for removal of existing growth of algae and lichens the treatment solutions are ap¬ plied in the same way as when new building materials are treated. Hereby the growth is killed and loses its grip in the building materials and falls off so that the original colour of the building material is re¬ created. In the case of outdoor structures rain assists in washing off the killed growth. The method according to the invention is preferably car- ried out with concentrated solutions of the copper salt and the soap, respectively, seeing that a single treat¬ ment with each solution is then sufficient to give a prolonged effect. The invention is further illustrated by the following examples. « Example 1 Eternite sheets for roofing were first treated by coat¬ ing with a concentrated aqueous solution of copper sul¬ phate and then, also by coating, with a concentrated solution of soft soap (potassium soap) . The eternite sheets were placed as a roofing on a dwelling house in 1960 and in 1979 it was ascertained that the roof was practically free from lichen and had retained the nat-. ural colour of the eternite sheets almost unchanged. This means a very much prolonged growth preventing ef¬ fect compared to known methods where the duration of the effect is measured in months or very few years. Example 2 An eternite roof made in 1962 and which in 1972 was dark from growth of lichen was treated by coating first with a concentrated solution of copper sulphate and subsequently with a concentrated solution of soft soap. After the treatment the lichens died and were gradual¬ ly washed off by the rain, and at a judgment in 1979 the roof had still the natural grey colour of the e- ternite sheets and was without growth. Example 3 A vertical surface of an old concrete bridge carrying a growth of black, brown and yellow algae and lichens was 2 treated by coating within an area of about 1 m first with a concentrated solution of copper sulphate and then with a concentrated solution of soft soap. The growth was killed and washed off so that the natural grey white colour of the concrete reappeared. A year after the treatment the concrete surface had retained its natural colour and no invasion of growth to the cleaned area from the surrounding uncleaned surface had taken place.

Claims: Claims : 1. A method for the prevention or removal of growth of algae and lichens on porous building materials by first treating the building materials with an aqueous solution of a copper salt and then with a binder which binds copper compounds in the building materials, c h a r a c t e r i s e d by the use of a soap solu¬ tion as the binder. 2. A method as claimed in claim 1, c h a r a c ¬ t e r i s e d in that the treatment is carried out by applying the solution by coating. 3. A method as claimed in claims 1 and 2, c h a r a c t e r i s e d by the use of concentrated solutions of the copper salt and the soap, respectively.

Inventors: KURE V
Applicants: KURE V
Application year: 1981
Main classification: B27K3
IPC codes: A01N59, B27K3, C04B41