How to identify rust stains
Rust stains can look identical to tannin stains. However, there is a simple method to
identify 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. If
the stain is unaffected by the application of rust converter, the supplier of the formply
should be contacted.
Grain Raising or Surface Swelling
Grain raising is caused by moisture penetrating the phenolic surface film and causing
swelling of the surface veneer.
The causes of grain raising are:
- Severe weather exposure
- Failure to use release agent or form oil
- Damage to the phenolic surface film i.e. misuse of vibrators, handling damage
etc. - Faulty phenolic surface film
As mentioned previously, the purpose of the phenolic surface film is to minimise moisture
penetration of the surface veneer.
Note that the phenolic surface film is not “water proof” and only slows the penetration of
moisture to an extent that grain raising becomes manageable.
The use of form oil and release agent is critical to prevent grain raising.
No formply manufacturer guarantees a Class 2 surface finish where a release agent has
not been used.
The effectiveness of the phenolic surface film is greatly enhanced by the application of
form oil.
