The best open-access publishers make their articles open from the get-go, and leave them that way forever. (That’s part of what makes them best.) But it’s not unusual to find articles which either start out free to access, then go behind a paywall; or that start out paywalled but are later released; or that live behind a paywall but peek out for a limited period.
Let’s talk about these.
Initial “open access”
You’ll sometimes come across journals where articles are free to read for some initial period after their publication. For example, the announcement of the Journal of Photonics for Energy says “The journal will be available as open access for the first year”; and the 2008/9 progress report for the Journal of Nutrition says “We will continue to restrict open access for one year, as per current procedure”.
Despite the good intentions of the journals, these articles are not open access in any useful sense. The point of an open-access article is that it’s there when you need it. If it’s there this week, but I need to read and cite it next week when I can’t get it any more, then that’s no good.
Of course, this doesn’t mean that publishers have a mandate to keep articles up on their web-sites forever (although we would prefer that they do). What it means is that, if they want to be open access, they can’t prohibit others from mirroring and archiving those papers, and continuing to make them available after they’ve disappeared from the publisher’s site.
Note that any article published with a Creative Commons licence — even the most restrictive of those licences — is safe from this kind of disappearance. Those licences guarantee third parties’ rights to archive, replicate and redistribute the articles.
Delayed open access
it’s probably more common to take the opposite approach. Some journals, including Science and Proceedings B, make articles free to read, and so “gratis open access”, after an embargo period during which they are available only to subscribers. This period is one year in the case of both these journals; that seems to be typical.
Are such journals open access? I would say that the journals themselves are not open access, but that the articles become open access once they cross the release line. So for example, Raichlen and Polk’s new neurobiology paper in Proc B. is not open access, but Anderson et al.’s seed-dispersal paper (which is a year older) is. On that basis you might choose to refer to Proc B. as a “delayed open access” journal.
[Unfortunately, Science is not truly open access even for older articles such as Stevens and Parrish's DinoMorph. That's because it requires registration/login before you can get to the papers. The BOAI FAQ does not accept registration-required content as open access, specifying "without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself".]
Transitory “open access”
And then you have the worst of both worlds. Every now an then a journal or a publisher has a special offer where they open up access to their articles for a limited period — for example, this one where the Royal Society opened up all their content for two weeks, or this where an issue of European Physical Journal D was opened for a week.
It seems churlish to criticise a generous action like this, but I find it close to useless, and I think most other researchers will, too. When I am working on a paper, I don’t choose what to cite based on which journal or publisher the papers are from: I would never think, “Oh, let’s see, European Physical Journal D is open at the moment, I’ll cite something from there”. I cite what’s relevant and appropriate, irrespective of its source; and if I can’t get the papers I need at that time there’s a problem.
I sometimes wonder what publishers think will be the result of this kind of limited-time-only offer. One obvious outcome is that people will batch-download the transitorily available content — either to store up for themselves in case they even happen to need it (which is wasteful of both bandwidth and storage); or to post openly elsewhere for permanence (which is usually a violation of copyright).
To summarise: I think that making articles open access after a delay is a good thing (though obviously not as good as making them open access immediately!). But that making them free to read for a limited time — either when first published or as part of some special event later — is of very limited value, and can’t really be described as open access.
