Rel=Canonical for filter pages

[LukeyB30]

Hi folks,

I have a bit of a dilemma that I'd appreciate some advice on. We'll just use the solid wood flooring of our website as an example in this case. We use the rel=canonical tag on the solid wood flooring listings pages where the listings get sorted alphabetically, by price etc.
e.g. http://www.kensyard.co.uk/products/category/solid-wood-flooring/?orderBy=highestprice  uses the canonical tag to point to http://www.kensyard.co.uk/products/category/solid-wood-flooring/ as the main page.

However, we also uses filters on our site which allows users to filter their search by more specific product features e.g.
http://www.kensyard.co.uk/products/category/solid-wood-flooring/f/18mm/
http://www.kensyard.co.uk/products/category/solid-wood-flooring/f/natural-lacquered/

We don't use the canonical tag on these pages because they are great long-tail keyword targeted pages so I want them to rank for phrases like "18mm solid wood flooring".

But, in not using the canonical tag, I'm finding google is getting confused and ranking the wrong page as the filters mean there is a huge number of possible URLs for a given list of products. For example, Google ranks this page for the phrase "18mm solid wood flooring"

http://www.kensyard.co.uk/products/category/solid-wood-flooring/f/18mm,116mm/

This is no good. This is a combination of two filters and so the listings are very refined, so if someone types the above phrase into Google and lands on this page their first reaction will be "there are not many products here". Google should be ranking the page with only the 18mm filter applied: http://www.kensyard.co.uk/products/category/solid-wood-flooring/f/18mm

How would you recommend I go about rectifying this situation?
Thanks, Luke

[TopFloor]

Depending on the CMS you are using, you may be able to add a dynamic element to the URL when more than one filter is being used, for example noidx=true. Then utilize your robots.txt file to disallow all URLs with noidx=true. This should allow pages with one filter to get indexed and crawled, but when a user (or Googlebot) enables another filter, that page would not be entered into the index.