The requirements in 1.7.15 of UL 1950 are : - Compliance is checked by inspection and by rubbing the marking by hand for 15 s with a piece of cloth soaked with water and again for 15 s with a piece of cloth soaked with petroleum spirit. After this test, the marking shall be legible; it shall not be possible to remove marking plates easily and they shall show no curling. The petroleum spirit to be used for the test is aliphatic solvent hexane having a maximum aromatics content of 0.1% by volume, a kauri-butanol value of 29, an initial boiling point of approximately 65EC, a dry point of approximately 69EC and a mass per unit volume of approximately 0.7 kg/l.
My recollection is that the sentence beginning "the petroleum spirit" was added to CLARIFY exactly what should be used. It has been suggested to me that doing the test EXACTLY as specified is less severe than just rubbing with petrol (gas to you). i.e. rubbing with water leaves a film of water, followed by rubbing with petrol. We use a UL Recognized Printing Materials system (PGJI2), where the combination of label stock, ink ribbon, and printer gives you a label which satisfies UL requirements. We use a system from Donprint, which also is CSA Certified, and we have NEVER had UL or CSA carry out any tests. As an aside, one of the advantages of buying UL 1950 on disc is that you could copy the above extract and insert it in an e-mail such as this, rather than typing it out. John Crabb, Product Safety NCR Financial Solutions Group Ltd, Dundee, Scotland.
