This article is a follow-up to the one I wrote in September 2000. If you haven't already read that article, please do so.
The choice of glue has been the most debated issue with my original article. I've heard many people complain that ordinary white glue is too brittle and can easily crack. This has not been my experience as the product I use seems to have a little bit of give. You can get craft glue that is specifically formulated to be somewhat flexible. Rubber cement is also a possibility but I find it a bit too awkward to work with. Another recommendation is to use glue that is rated as "archival" and/or "pH Neutral". If you do, make sure that you use stuff that will cure completely—sticky corners will be less than useful.
Ultimately, you'll need to employ trial and error to find the glue that works best for you.
Another common recommendation has been the use of a hot glue gun rather than more conventional glues. These do have the advantage of being quite strong and setting very quickly. So quickly that you will not need to use braces and clips at all. Simply apply the glue, press the sides together for 5-10 seconds and you're done.
Despite this, it's not a method I can recommend because hot glue is very unforgiving when applied to cardboard. If you get it on the wrong spot, it may be impossible to remove without tearing the paper. If you do want to give it a try I'd suggest using one of the smaller "craft" glue guns rather than the larger variety. Either way, proceed with caution.
My original article was intended to detail a process that was as "invisible" as possible. Sometimes it's better to go with greater strength and in these cases I recommend using corner braces in addition to gluing the edges. You can buy these commercially but it's even better to make your own so that you can customize the size perfectly.
Get some heavyweight cardstock. You should be able to get 110# stock at any office supply store.
Cut strips. The height of the strip depends on the size of the box you're repairing. You want the brace to go from the bottom of the box to just below the paper that's folded around the box edge. (see photo below)
Cut the strip into individual braces. The length is not critical but 2" is a decent size.
Use a straightedge to crease the brace. The critical thing here is that you do not want to make this crease too sharp, if you do, it will decrease its strength.
Repair the corner as per my original method. Make sure to let everything dry before proceeding further. It's best to do this a previous day so that you're not tempted to continue before it's dry.
Apply a small bead of glue to the corner of the box.
Apply glue to the back of the corner brace, spreading it around with your finger.
Place the brace into the corner of the box. Use a sharp instrument (the dull side of a kitchen knife works well) to force the corner of the brace into the corner of the box. You want to make sure that it's nice and tight so that the top will still fit over the bottom. The edges of the brace may tend to curl up at first but if you hold them down for a few seconds they'll eventually hold.
- Let it dry overnight and you're done!
If you have multiple splits on a box on which you intend to apply braces, I'd advise doing them one at a time. This is because the brace will add a certain thickness to the inside of the box. If it's already a tight fit, adding a brace to each corner could result in a top that no longer fits the bottom.