Blogging for Thor: Halo There!

I had a lot of fun today playing salted paper prints, but that isn't what this blog is about. That's because I had this thing to talk about first, and also because the salt print blog is going to take a while to write and it's 10:45 right now, as I start this. I wouldn't make the midnight deadline if I did the salted print post. Plus, in all fairness to this post, I did have the idea for it first. Mostly.

You know what, spiders, just read the blog. This post is actually informative and useful, while the salt print one is just kinda cool and fun. So there's that, too. Not sure what else there was.

Pre-exposed print with emphasized halo

One of the really cool things about lumen prints is that if you use fresh plants to make your contact prints, there will often be a "halo" around your subject. The moisture in the fresh plant material sweats out under the sunlight and heat, soaking into the paper. The wet paper reacts differently to light than the dry paper does, creating a different hue or value depending on what kind of paper you're dealing with.

This week's fun fact is that you can dramatically enhance the appearance of such halos by leaving your lumen print out to "pre-expose" under indirect light or interior lights. The low amount of light is enough to begin the exposure of your paper, and start the moisture reaction, but not enough for a big dramatic tonal shift that will produce a vibrant lumen. So the halo has time to creep outward with the moisture while the exposure is still happening fairly slowly and subtly.

Once your halo has been established in a few minutes to a few hours, take your print outside and let it expose in direct sunlight. Now, all at once, the halo and the background will darken dramatically, creating a very stark, very visible halo in your image. That's because the low light allowed it to form first, then expose. When you just expose a lumen normally the halo is struggling to form while exposure is already happening all around it. The moisture doesn't have time to sink in and affect the paper as much, because more of the paper is being exposed before the moisture can spread out.

Regular print with faint halo

A pretty cool trick, and one I can't take credit for. I learned it from John Fobes, who is another enthusiastic lumen printer with far more experience than I have. He discusses the idea a little bit here, in this particular image. Here's the relevant quote:

Polycontrast is capable of producing a nice halo if you prepare the specimen [and] first let the prepared print sit for a few hours under weak room light before you expose it to sunlight.

Mr. Fobes is referring specifically to one type of paper (Kodak Polycontrast II), but it holds true for many types of papers since the underlying mechanic of the halos is the same. Note that this technique works best in hot places, because the heat will wither the plant material faster, releasing more of that lovely moisture onto and into your paper. That's another reason why spring and summer are the best times to work with lumen printing.


Whelp, that's all Spiders!