Preserving and presenting your seaweeds

In the name of educational advancement, I hope the University of British Columbia Herbarium don't mind me showing you this beautiful example of a seaweed herbarium sheet to inspire you.

Larger sturdier specimens can be pressed immediately between newspaper in a botanical press - remember to lay them out in the arrangement you'll want for the final display. You might need to check and change the paper more often than for less soggy plants - you don't want your specimens to go mouldy. Some herbaria recommend cutting the biggest stipes or structures in half if you want to press them. (Peter Mcinnis suggests that they can be encouraged to press by being soaked in hot seawater - I guess, bring some home with you and heat it up!)

The specimen in the photo at the top will have been 'floated'. For this you'll need a tray of water. If your seaweed is rather delicate, it's likely to end up stuck to the paper you use now - so herbarium paper or artists' paper is good (we have some you can use). Put the paper in the tray (possibly with something as a firm layer behind it) and spread your specimen out on top, so the water helps you arrange the delicate structures with forceps or a paint brush. With really bushy specimens (eg. the calcareous red species) you might want to prune some areas so the branching patterns of a single layer are more easily seen. Grattan describes the process in detail (he does suggest you need a porcupine quill and an ivory paper knife, but you can probably manage without those, thank goodness).

Image by Peter Mcinnis (public domain)

Remove the paper carefully from the water, blot it as much as you can, and then transfer to it to your press, layering with newspaper.  Don't forget a label!  Tighten your stack of specimens really firmly and put it in a warm pace to dry. When you reopen the press to change the paper, I've read that you should allow the papers to cool first or the specimens may curl.

W H Grattan's seaweed press

I've written some advice about making and using your own press here.

And what I've written here about mounting specimens will also have a lot of relevance for your seaweed collection - some you might want to tie on, or you might use glue.

Update: I've found this rather comprehensive guide to preserving your seaweed here, at the Cryptogamic Botany Company. It's easy to read and has lots of photos.