Good Slate Or Bad Slate – How to Tell The Difference
All slates are not created equal and as we mentioned in a previous blog, slate can vary a lot in quality depending on where it is sourced from.
One of the major problems with poor quality slate is tendency to change colour when it is exposed to the elements.
Minerals within the slate can react to rain and change colour which can be undesirable and in the worst cases it may not even be waterproof after a time. So it is wise to spot the good slate from the bad slate to prevent either of these troublesome issues from happening on your roof!
The first thing to look for is that it meets the EN 12326 standard. While this should by no means be taken as a mark of quality it does ensure that the slate conforms to minimum standards of quality.
To really look at the quality of slate you need to look carefully at things like colour. Welsh blue grey and heather purple slate are regarded as the best types of slate but this is now expensive with demand high and only a limited number of quarries supplying it.
Next you can tap the slate to listen for what type of sound it makes. If the slate makes a dull or rattling sound rather than a ringing sound then it is likely to be poor quality. Testing slate for brittleness is also a reliable indicator of quality. Good quality slate isn’t brittle and won’t shatter.