We had our Victorian internal doors "dipped" to remove the paint. The rest of the woodwork we stripped with a blow torch. The stripped doors stood in the garden shed for several months, but we have now brought a few of them in and rehung them. In many cases the wood panels split from shrinkage in the hot dry house.
So the question is: has the dipping (in caustic soda I guess) made them more vulnerable to splitting? and is there anything we can do to reduce the risk, such as applying oil or something?
Is it the "inset" panels ( sometimes surrounded by mouldings,particularly on the "good" side ) that have split? I think only one of mine had this happen but as they were being painted it didn't really matter . I suspect that part is made of an inferior wood so maybe that is why it happens .....can't see any way of replacing it either due to the way the door is constructed .
It's caused by the panels not being able to slide in the groves in the timbers, so when the panel shrinks, it splits rather than pulling out slightly from the surrounding timbers.
This is often due to painting or varnishing in the edges of the panels, which has effectively glued the panel edges. If you want painted panel doors, you would do much better to get modern molded ones to start with. If you want to see the timber, then you should probably wax them rather than varnish them.
I can't see how the dipping would cause this, unless it perhaps expanded the panels more than they normally would, and they got stuck in the expanded position in the side timbers, so they couldn't shrink as they dried.
No, it was dipping them for too long in weak caustic soda that did this, i.e. an exhausted or an unheated bath, where they were left in too long to compensate.
There's little you can do about this. The real fix is to be more careful about using a competent stripper.
A general problem with old doors is that they were built for higher humidity than today, and better room sealing and lower humidity are making them suffer. A good frame & panel construction survives this (the panel can float free in the frame). If the panel is stuck in the frame (nailed, or jammed with ancient paint) it can stress the panel enough to crack it. Those cracks may be gluable, so long as you don't glue the panel into the frame as well, "to fix it".
Bringing doors in from a cold, damp shed in this weather directly into the house is pretty much calculated to split them. It would even have been better to leave them in the shed until Spring.
Oiling and surface coatings won't do anything over a 3 month cycle, such as winter weather. They'll reduce moisture movement over a daily cycle, but over the whole season duration, nothing is going to seal it for that long.
Thank you all. This is interesting. We can certainly leave the remaining doors in the shed until spring if it would help to dry them out slowly. We want to keep the mas bare wood so filling is not really an option.
We have upgraded the heating, so the hous eis probably hotter than it was ever been which would make it dryer as well.
Also, every door is different. As someone else pointed out, they have mouldings sometimes only on one side, just as the house boasts different styles of skirting boards in differernt rooms. this, along with the presence/absence of picture rail and corniceing, seems to be all arranged to mark out the 'owner' and 'servants' domains of the house. As soon as you get through the kitchen door, for example, all the skirting is small, there is no picture rail and the doors have no moundings.
I think you've subjected the doors to a series of shocking environmental changes, and each one would've caused some movement. Once they're acclimatised to the final, indoor location you should have any further problems.
To reduce splitting during that transition, you can pace it more slowly (eg bring the doors in during the warmer months, or wrap them in polythene and allow them to gradually adapt over a few weeks before unwrapping and hanging them).
As I understand it, it depends on what day of the week they are dunked. On a Monday morning the tank may have cooled down quite a bit having been off heat for the weekend. Hot dipping is better. I did my doors with Danish oil, just wiped it on with a rag.
Yes the dipping or stripping will have made the wood more susceptible to splitting. Paint and varnish has a protective effect, stopping water from getting in to the wood. If you leave the bare wood open to the elements it will absorb water and swell. When you bring the wood back into the house the wood dries and shrinks again, but unevenly. You might be able to prevent this by either oiling the wood immediately after dipping/stripping or by drying the doors slowly.
One of the problems is that caustic penetrates deeply into old timber, and no amount of rinsing/hosing gets rid of it all. The residue is hygroscopic, with the result that parts of the wood may never dry out completely. Grey streaks on panels are common, the darker bits usually being sapwood. Hydrogen peroxide will make them paler, but doesn't address the drying out issue. Neutralising the caustic residue with vinegar achieves little because the resulting salts are equally hygroscopic. I think you have to accept the splits, and any other distortion, as a feature. A couple of my doors are split, and banana shaped to boot. The Victorians didn't allow for central heating.
What I found with the cooler dips is that the doors came back furry, that is, the surface of the wood wasn't smooth. Maybe it was just those particular doors I guess it is difficult to determine which is the best temp. unless one is present with a thermometer when the doors are dipped.
Dear Robert I used sodium and potassium hydroxide to extract hemicelluoses (five carbon sugars) from timber in doing my thesis. It was necessary to make the timber into sawdust in order to do so as the material had such limited penetration into the side grain of whole wood so I would take with a pinch of salt (absent any scientific paper or evidence to the contrary being supplied) assertions that caustic soda has deeply penetrative powers. If that were the case we would not have used OS to "treat" wood under pressure in plants. It all depends on the porosity and permeability of the wood and I guess it is likely to be in the order of magnitude of one or so mm. What might make a timber split is moisture content - water getting in Dependent on the time heat and duration of the dip that might well be a considerable distance (steam was used to bend planks in ship building) That is you likely candidate for splitting
How to reduce risk?
limit dip time to that just for paint use an organic stripper do all the other sensible things mentioned by others such as not having panels too fixed in grooves above all keep out the water
Grain raising can happen hot or cold. It's partly to do with the species of timber and sometimes what was on there in the first place. For some reason the old spirit varnishes don't dissolve cleanly. I had my own tank for years but never really discovered why.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.