Page 127 - 20250602 EEA QM Edition 6.0

Quality Requirements Edition 6.0 European Enamel Association

8.7.4 Valuation of pores in enamellings Consideration and Description

The judgement of damage by pores is performed by naked eye. One differentiates:
Definition and cause

Following the definition of DIN 50903: Pores are locally limited interruptions in the a. open, pulling through pores
enamel- ling. Pores are caused by gas reactions during the firing process. Their b. open not pulling through pores
largest extent is mostly found vertically to the enamel surface. Pores are often -
especially in light coloured direct-on enamellings - connected with black specks. In Open, pulling through pores are interruptions in the enamelling down to the metal
these cases, gas reactions during firing convey the adhesive layer, being rich in iron substrate. They can be made visible by physical (e.g. electrostatic) or chemical methods.
oxides, towards the surface.
Open, not pulling through pores cease in the enamel layer. They cannot be made visible
by such method, as there is no prerequisite reaction with the metal substrate.

Test report
In the test report to be mentioned:
kind and origin of the test piece
place and date of testing
description of defect, number and size

Direct-on enamelling / pore with black speck (enlargement 200 : 1)

Conventional enamelling with a pore not pulling through (enlargement 200 : 1)

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