Which Is The Best Bluestone?

Which Is The Best Bluestone?

An Overview

Which Is The Best Bluestone? This is a commonly asked question and the answer is not straightforward. Without going into the technical aspects of Bluestone, which this article does not attempt to do, I will try to give a summary of the situation in Victoria as it stands now. For those who like the science behind this summary, a good article to read is contained within Discovering Stone issue 22 2012.

Since the foundation of Melbourne City Bluestone, which has the geological name of Basalt, has featured strongly in our churches, walls, foundation stones and all aspects of building. Our local Bluestone responds well to traditional methods of fixing using mortar (a mix of sand and cement). As a result Bluestone had an excellent reputation as a building product.

In 2005 Edwards Slate & Stone imported a variety of Bluestone that closely resembled the Australian variety of Bluestone from a part of China in both colour, pore size and the distribution of larger holes which is locally called “cats paw”. This type of Bluestone was substantially cheaper than the Australian variety and as a result started the resurgence of Bluestone as a tile in the domestic housing sector. This type of Bluestone could be laid in the traditional manner using mortar, the only slight disadvantage was that it sometimes contained a minimal amount of iron than the locally quarried Bluestone and as a result an occasional tile could discolour slightly. This can be neutralised with certain easy to obtain chemicals.

In 2011 we became aware that there were a number of failures to do with fixing Bluestone in Brisbane and Sydney. Up until then we had not heard of any failures in Melbourne. In 2012, as best as we can tell, large volumes of Chinese fine pored Bluestone began to be imported into Melbourne and with this the number of failures to do with fixing began to rise. When we say Chinese Bluestone I should qualify what this means. The two main areas for quarrying Bluestone In China are around 1400kms apart, that is from about Melbourne to Coffs Harbour in distance. The nature and quality of the Bluestone pavers varies considerably depending on where it is quarried. On this basis it is impossible to say “All Chinese Bluestone is bad” or “All Chinese Bluestone is good”, it really depends on where it is quarried and other factors such as thickness and size, which this article does not attempt to discuss.

Between 2013 and the date of this article, very large volumes of a particular type of fine grained Chinese Bluestone has been imported into Victoria and the resulting failures during the fixing process has increased alarmingly when this stone was used.

So this leaves us with two questions. The first is why are importers choosing this new type of fine grained Chinese Bluestone and secondly how would it be laid successfully if you cannot use a traditional method?

The first is easy to answer. Originally I do not believe importers realised that they were importing a variety of Bluestone that could not be laid using traditional methods. And the price of the fine pored material was cheaper and could undercut the existing variety of bluestone on the market, so it was easy to gain considerable market share quickly.

Secondly the market demanded a consistent colour and fine grained finish, both of which this new variety of Bluestone displayed.

Unfortunately the results for the end user could be catastrophic when regularly the entire bond between the mortar and the tiles failed in the first few hours after fixing. We have also heard many reports that even if adhesive is spread onto the tile before fixing into mortar the bond still breaks.

What Is The Solution?

We suggest purchase from a well established company with a good reputation. Ask the supplier, “Is this Bluestone suitable for use using traditional fixing methods?’ And be wary, a substantially cheaper price may not always save money in the short and long term.

Conclusion

A good quality Bluestone from China will last a lifetime and provide an easy to care for and slip resistant surface. The colour never dates and compliments modern and traditional homes, and the range of complimentary bullnose and drop face for pool coping tiles is second to none. I have chosen Chinese Bluestone for my own home and the results have been outstanding.

Steven Edwards