Grain Raising or Surface SwellingGrain raising is caused by moisture penetrating the phenolic surface film and causingswelling of the surface veneer.The causes of grain raising are: Severe weather exposureFailure to use release agent or form oilDamage to the phenolic surface film i.e. misuse of vibrators, handling damageetc.Faulty phenolic surface filmAs mentioned previously, the purpose of the phenolic surface film is …

How to identify rust stainsRust stains can look identical to tannin stains. However, there is a simple method toidentify stains associated with rust or oxidised iron. This involves applying “rust converter”to the stain. If the stain fades or disappears, the stain is caused by rust or oxidised iron. Ifthe stain is unaffected by the application of rust converter, the supplier …

Staining in FormplyThe most common stains associated with formply are: Rust stainingTannin stainingPinking – free phenol from the phenolic surface film.In the writer’s experience, most staining is due to rust deposits on the deck at the time ofpouring or iron in the aggregate. These stains appear red/brown and are often mistakenfor tannin staining.Tannin staining is the result of extractives from …