Just had a chat with the sister. She said Spanish slate was about £1.50, local Welsh about £3 when she had the roof done. Prices are similar now. The Spanish industry was (is?) heavily subsidised. It is one of the wonders of the EU that one nation can do that at the expense of another.

Sep 19, 2019 at 10:17 AM | Rhoda Klapp
Sep 19, 2019 at 10:42 AM | AK Thank you for the Geology!

The slate industry was hit by the artificial slate industry, ie thin bits of reinforced concrete, coloured to look like slate. Until the 1990s, the reinforcement used was a fibre containing asbestos fibres.

Artificial slates are still produced (without asbestos) and they look uniform initially. They then appear to bleach a bit, and some adopt a bit of "curvature".

Slate roofs fail over time, NOT because of the slate, but because of "nail sickness", which is a euphemism for rust.

The EEC ruling that "Welsh Slate" was not a superior product, and could not be "required" by National Parks, Listed Buildings, Historic Monuments, Planners etc, was one I was never comfortable about, given the protection provided to "Champagne" and other products.

"Even then there was talk of using the huge tips of mining waste. Has anything come of this?
Sep 19, 2019 at 10:42 AM | AK"

You can buy decorative slate chippings for landscape gardening .......

Rhoda. How very interesting. A near complete reversal of economic values. I suppose in part the original high value of Welsh slate was also due to a concentration of skilled slate splitters in the area. With increasing wages the product became uneconomic. I visited the mines when they were in sharp decline in the 1960s. Even then there was talk of using the huge tips of mining waste. Has anything come of this?

Teen climate activists attend a hearing to address the climate crisis and its traumatic effect on the younger generation"
https://www.theguardian.com/us-news/2019/sep/18/greta-thunberg-testimony-congress-climate-change-action
Sep 19, 2019 at 8:46 AM | Mark Hodgson
Sep 19, 2019 at 8:45 AM | Mark Hodgson

Our schools and universities are not preparing students for some of life's genuine hardships.

GC. North Welsh slate is genuinely world class and at one time was shipped world wide (I have seen it adorning roofs in New Zealand). I believe its perfection comes from two main features. Firstly its splitting (or cleavage) is near perfect (= flat) over large surface areas. In other slates the cleavage is not so perfect displaying flexures or interrupted by small folds. Secondly the original muds were laid down in a deep trench and were exceptionally fine-grained (mostly uniform clay, little silt). This meant that when the muds were subjected to tectonic pressure they developed their near-perfect cleavage. Its uniformity allows slates to be made to near-uniform thickness.
Welsh slates are an example of a commodity that broke most economic rules. Most earth materials (except gems) are expensive to transport and thus have limited geographic reach. Welsh slates were sent by ship worldwide such was their uniqueness.

I thought the NHS switched from using laughing gas as an anaesthetic a long time ago. But perhaps I am wrong.

https://www.nhs.uk/news/medical-practice/anaesthesia-with-laughing-gas/

GC, my sister lives within sight of the Blaenau Ffestiniog slate quarry. When she had her roof replaced she used Spanish slate, local just cost too much.

Sep 19, 2019 at 8:07 AM | AK
Sep 19, 2019 at 9:37 AM | It doesn't add up...

The Welsh Slate industry was hit by the EEC and Spanish Slate industry.
https://www.independent.co.uk/news/welsh-hillside-told-to-welcome-spanish-slate-1587299.html

Are there genuine geological reasons (or is it quarrying techniques?) that make Welsh Slate a superior product?