I stretch my shawls a lot when I block them. Most shawls will shrink back a bit after they're dry and unpinned. The more wool content the shawl has the more it'll shrink back. Silk content helps the shawl to keep its blocked shape better which is why I love yarns with some silk in them. Having said that, the Botany Lace used in this shawl is pure merino and is gorgeous and actually feels very silky.
I stretch my shawls as much as I possibly can. With shawls you don't have to worry too much about blocking them to the exact size as listed in the pattern. Its better to block them to your tension. I stretch mine as much as I possibly can then I stretch them a bit more. Keep going around the shawl and adjust the pins and make sure it's the way you want it then leave the shawl to dry. I normally leave mine overnight although sometimes it'll take part of the next day too.
Yesterday before I took the shawl back to Spin A Yarn I took some pics of the blocked shawl. My shawl came to Coventry with me over the weekend and has been folded and stuffed in a carrier bag and as a result it has shrunk back a little. The pics below are not great. I took these pics about 9am yesterday and the light was appalling and it was wet outside so I had to do photos inside.
The Spin A Yarn shop sample is below my shawl in this pic and you can just see it peeking out underneath my shawl so the shop sample ended up being slightly bigger than mine.
Here's the shop sample on it's own. Excuse the poor pic but you can still see how much bigger and better it looks. I returned this sample to Spin A Yarn yesterday and I think Joyce and Ali were surprised to see how much bigger it looked and Joyce wore it for the rest of the morning.
If you're still unsure about whether it's worth taking the time and effort to block a shawl, try it on your next shawl. Take a pic and measure the shawl then block it and compare the results. I'm sure you'll agree it's worth it.
Has this made you want to knit Mar Menor? Pattern can be found here and here.