Principles to minimise potential problems with Class2 and Class 3 off form Surface FinishesPrinciple One: Most issues with off form surface finishes are associated with moisture.Wherever possible protect the formwork from weather. This includestarping where practical.Principle Two: The phenolic surface film used on formwork plywood is not impermeableto moisture. To ensure that moisture penetration is minimised, releaseagent and form oils …

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 …