Solid wood
What humidity the wood can have when coating is applied? While painting, coniferous wood in the external elements should have a humidity of max. 12%. When painting interior parts, the wood humidity may be max. 10%, and in rooms with central heating it should not …
Copper
How patina is formed on copper?
Firstly, the copper surface oxidizes in air, forming a brown layer of copper oxide. Then, under the action of carbonic acid contained in the air, a water-insoluble copper carbonate is formed, that is, a patina of green color.
Why in polluted by …
The alkaline reaction of the concrete protects the reinforcing steel against corrosion. Where does this alkaline reaction come from??
During the hydraulic hardening of cement, which is a binder in concrete, a significant amount of calcium hydroxide is formed (lime lye). It is calcium hydroxide that is the source of the alkaline reaction of concrete.
What value should …
Inside the room, on a brick wall, dark joints are marked between the wall blocks.
What is a cause of it?
There are so-called. thermal bridges. Due to the insufficient thermal insulation properties of the wall, mortar joints are visible on it. Due to increased flow …
On the smoothly blurred facade of the building, covered with plaster made of PIIa mortar, cracks of a dynamic nature and mesh cracks appeared on a large surface.
The old paint coating from dispersion paint shows no damage and sticks to the substrate well, but it is …
Cast
How does plaster bind?
Gypsum is chemically bonded by attaching water. The water lost during firing combines with the gypsum again during its setting after adding mixing water.
Please explain, why gypsum is not suitable for external use…
Please calculate the thickness of the thermal insulation layer made of expanded polystyrene, so that the partition analyzed above would reach the value of the k-factor below 0,40 W/(m2K). The influence of the adhesive layer and the protective coating on the thermal insulation layer can be neglected here. Thermal conductivity for polystyrene is 0,04 …
What is the recommended pretreatment of an aluminum substrate?
The aluminum substrate can be pretreated by:
1) manual cleaning with nitro thinner, and then wiping with an abrasive fleece;
2) manual cleaning with a cold preparation, then rinsing with hot water and wiping with an abrasive fleece;
3) manual cleaning …
Large areas of paint peeling off the hot-dip galvanized steel sheet roofing. It is necessary to paint the roof. Please list the necessary steps for painting the roofing. These steps are as follows:
1) complete removal of the old coating by scraping it off;…
What materials are recommended for coatings on a zinc substrate?
Dispersion paints are suitable for making coatings on a zinc substrate, dispersion varnishes, alkyd varnishes, PVC varnishes, made of chlorine sulphonated polyethylene, polyurethane and epoxy, asphalt, tar-epoxy and special paints with high …