I managed to get out and epoxy that mystery crack today, and I thought it would be a good opportunity to discuss how to work with this LiquidWood I talk so much about. On the one hand, it's just another two-part epoxy like the stuff you've all used before, but on the other hand it's just different enough from what you're likely used to that if you just go grab some and start using it without reading the voluminous directions you may be disappointed in your results. As always, Dear Reader, I am here to try to give you the benefit of my own drats.
This LiquidWood is specifically designed to be used with wood. It has a consistency somewhat thicker than corn syrup, but not as thick as honey. It sets relatively slowly, in order to give it plenty of time to flow through the wood beforehand; in fact, there is as a practical matter no fixed set time. This is where LiquidWood gets tricky, and this is where I had difficulty in my first uses of it.
The reaction between the two parts of epoxy generates heat, and heat accelerates the reaction. Moreover, there must be a certain temperature reached before the reaction gets underway successfully. With the usual fast-setting epoxies one uses, this is not an issue, but it is crucial with a slow-setter like LiquidWood. Without going any further into the theory, here are some practical rules to follow when using it.
Whatever volume you mix up, always start with a container that holds that volume in a shape that is taller than it is wide. Here, I am using one ounce (one-half ounce of each part); I took the picture before I mixed them just because it looks rather nifty that way.
Mix them thoroughly, so the mix appears entirely uniform throughout, and let the mix sit for ten minutes. This gets the reaction going sufficiently to ensure full curing once it is dissipated within the wood.
While I was letting the mix sit, I prepared the crack for gluing. First, I marked it with a pen so that I had a more visible target to work with.
At this point, I realized that the crack was too tight to allow sufficient penetration of the epoxy without some help. Because of the location within the triple-bead profile, I didn't want to use my usual method of drilling holes along the crack on both sides, so I decided to drill a few strategically-placed holes directly on the crack. This was a delicate operation, because the wood along a crack is naturally quite fragile, and I had to be very careful not to splinter the wood as I drilled (which is why I usually don't do it).
So far, so good. In order to get the epoxy as far into the crack as possible, I poured it into a small squeeze bottle with a conical tip sized to fit snugly into the holes, and squeezed it in slowly and repeatedly until it would take no more.
At this point, I knew I could rely upon capillary action to carry the epoxy all along the crack in sufficient volume to keep the wood stable. Fortunately, the crack was pretty stable to begin with, and it should not be subject to any particular stress. I then applied a clamp as close to the crack as I could without damaging the splintered area I have yet to repair; this eliminated any remaining air pockets and maybe even generated a bit more heat to aid curing.
As remote as the clamping location appears, it nonetheless closed the crack tightly along its entire length. This suggests to me that there is a lot going on inside the wood that we don't see here, i.e., this crack may go rather further down the piece along the back side.
This brings up one of the differences between renovation and restoration. If I were working on a forty-year-old ranch house and I had a crack like this in a window casing, if I wanted to do a truly thorough job I'd pull this piece of wood off the house completely at this point, and fix this crack from both sides. I might even decide that the best course of action was simply to replace this piece. That would be renovation, and from the standpoint of effecting the best, most long-lasting repair possible, it is undoubtedly the best course.
But we're not renovating here. One does not renovate a 125-year-old house, at least not in Bungalow Heaven. One restores it. When restoring a house, one retains as much of the original building material as possible without compromising the health and structural soundness of the house. It's not compromising anything to leave this crack incompletely discovered; at worst, it just means that it may need further repairs sooner than it would otherwise. Moreover, if I were to take this old, brittle piece off with the full intention of re-attaching it, I would almost certainly damage the piece further, and might well end up damaging it so much that I'd have to replace it after all. I'd probably end up cracking some of the siding as well.
Thus, as much as I'd love to make the Farm House perfect, I have to stop fussing when the risks incurred in going further outweigh the benefits. I'm also in a bit of a hurry as well.
To finish the discussion of the use of LiquidWood, count on waiting overnight for it to harden sufficiently to remove any clamps, and depending upon the weather, at least 24 hours for curing. Heat and low humidity speed this process. If for some reason you end up with LiquidWood that refuses to cure fully (i.e., it remains sticky), get it good and hot with a hair dryer and keep it that way for at least ten minutes. That should do the trick, although you may have to do it a few times.
Oh, and one other thing: while epoxy is extremely low in toxicity, one can develop an allergy to it with repeated skin contact, and from then on working with epoxy becomes unpleasant, For that reason, always wear gloves when handling epoxy. If you should get it on your skin, clean it off with alcohol immediately. Alcohol is great for cleaning un-set epoxy off of tools and containers as well; I use the denatured alcohol readily available at any hardware store (even in California, at least for now).