PageRank Sculpting is, essentially, the practice of targeting PR by limiting link flow to other pages within a website. Adding a nofollow attribute to one link so that it will not take value away from other links on the page.
In a recent interview, Matt Cutts professed that PR sculpting was simply not worth the time, and here’s why: if there are 5 links leaving a site, each link is portioned about 1/5 of the link value. Preventing the 1/5 from flowing through one link does not necessarily re-distribute that share of the value to the other 4 links; therefore, that 1/5 is wasted. In addition to this, search engines want to follow the same path as a person navigating your site. If you’re sending a visitor to a page, a search engine wants to go there, too – not be sidelined by a nofollow attribute.
Instead of focusing your efforts on condensing PR, there are other ways to emphasize pages on your site. The starting point is your site architecture. Often, your homepage is the strongest page on your site and has the highest PR; therefore, the pages closest to the root (and to the homepage) will receive the most subsequent PR.
Using this principle, design your site in tiers: the most important pages are at the top (closest to the root) and link down to pages of secondary and tertiary importance. This organizes the priority of your pages and value is passed down accordingly.
Once your site architecture is organized, you can use link building to give emphasis to specific pages. The more incoming links a page has the more value a search engine perceives. Think of a bucket of water. Each outgoing link is like a tiny hole in the bottom of the bucket, leaking link flow.
Each incoming link (in SEO terms) is like a tiny stream of water pouring in link flow. If you can pour in linkflow faster than it is leaving, you’ll start retaining value and filling your bucket. By thoughtfully building the link flow on a page, you’re able to make the page noticeable to the search engines and thus, you’ve reached your goal.
As I’ve said before. It takes a combined effort of on-page and off-page optimization to make a site work. Molding linkflow is a perfect example of the symbiosis between the dual forms of optimization. Rather than trying to manipulate a search engine with PR sculpting, try to impress it with carefully planned linkflow design. The results will be stronger and the efficiency will be greater.