You proposed solution might buy you some time and your description sounds like you'be caught it in the early stages. The antifreeze method can be quite effective.
FREEZE WOOD MOTION WITH ANTIFREEZE
Ethylene glycol, or glycol, readily available as permanent auto antifreeze is the most versatile and effective treating agent for stabilizing wood against the dimensional changes caused by variations in water content. Glycerol and sugar solutions act similarly to glycol, but nowhere near as rapidly. Polyethylene glycol (PEG) can be used to stabilize wood, but operates by a different mechanism and requires a lengthy treatment process which can be used only on green or water-soaked wood.
Wood is a high-performance, low-cost, easily-worked material. Its principal disadvantage is that it absorbs water to a high degree and its water content changes when the humidity of its environment changes. Wood shrinks as it dries and swells as it picks up water. Sticking doors and drawers; loose furniture joints; cracking furniture, carvings, and woodwork; and boats that leak after they have been hauled out are common manifestations of the dynamic wood-water relationship.
Bruce Hoadley's book "Understanding Wood" has the most thorough exposition of the wood-water interaction I have
read. He says "Someone once quipped that more than 90% of all problems with wood involve moisture. For those who ignore basic wood-moisture relationships, that is probably a conservative estimate." A piece of green wood freshly cut from a log is like a sponge; its cell cavities are filled with water (free water) and the cell walls are saturated with water (bound water). There is commonly more water than wood in the piece. As the wood dries, the free water evaporates and leaves the cells empty. This does not shrink the wood, but after all the free water has evaporated the water in the cell walls begins to evaporate, the cell walls shrink, and the whole piece shrinks. Wood shrinks very little longitudinally, but shrinks considerably radially and tangentially; the resulting changes in the width and thickness of a piece of wood cause all the problems.
Common manifestations of wood shrinkage besides the changes in the dimensions of boards are warping, checking, and cracking. Furniture pieces open up gaps in the winter while doors and drawers stick shut in summer. Carvers and bowl turners working with massive pieces of green wood have their work ruined by gaping cracks as the wood dries out. Wooden boats hauled out for the winter open up the seams between their planks. All of these events are the results of water evaporating from wood or being reabsorbed by it as the relative humidity of the environment changes.
The ideal compound to treat wood to stabilize it would replace water in the cell walls, interact with cellulose as water does, and not evaporate - a "nonvolatile water". Glycol, available everywhere as auto antifreeze, approaches the ideal most closely.
Glycerol is the next best treating agent, but it acts much more slowly than glycol because it is less hygroscopic (less strongly attracted to water), is a larger molecule, and is much more viscous. Glycerol has been used commercially to stabilize wood and has been shown to be more effective than PEG in stabilizing wood.
Sugar solutions have been known to stabilize wood since the early 1900s. They have been used commercially and repeated scientific investigations have demonstrated their ability to stabilize wood. Sugars are quite large molecules, and since they are solids, have to be used as solutions in water. Sugars do interact with cellulose because they have similar chemical structures.
Polyethylene glycol (PEG) does not interact with cellulose. It is not very hygroscopic. It has to be used as water solutions which will penetrate only green or water-soaked wood, and that very slowly at room temperature. It stabilizes wood by filling the cell cavities and propping them up. After treatment, the piece has to be dried, and even after drying treated pieces are often difficult to glue or finish.
The discovery that polyethylene glycol with a molecular weight of l000 (PEG-1000) can stabilize wood against dimensional changes was made by A. J. Stamm at the Forest Products Laboratory. He published his first paper on laboratory results in 1956 and a paper on practical tests with green pine logs in 1959. Mitchell and other workers at the Forest Products Laboratory have published papers on developing recipes for treating various wood articles. Though Hoadley wrote "Antifreeze has no stabilizing effect on wood, so don't bother trying it." (FWW #19) and Spielman repeats the mythology in his book "Treating Green Wood With PEG", neither had tried antifreeze; the only factual statement they could make is that glycol antifreeze is different than PEG.
The spark that set off my investigation of glycol for stabilizing wood came from Stamm's original 1956 paper. In that paper he tested glycerol as well as PEG. He found that glycerol stabilized wood as well as PEG-1000, but he never did any more work with glycerol. After 40 years in industrial chemical research, I recognize the uncertainties of second-guessing another researcher, but I think Stamm ignored his own results on glycerol because he was biased toward large molecules as "bulking agents" for wood, a term he used frequently. Glycerol was just too small a molecule to fit his theory. I extrapolated from his results with glycerol to the idea that glycol should be better than glycerol because it is a smaller, more hygroscopic molecule. The wood technologist tests for wood stabilization by soaking a piece of green wood in the treating liquid or solution and then drying the piece in an oven at over the boiling point of water (100 C. or 212 F.) until it stops losing weight. Measurements of the piece before and after drying establish whether dimensional stabilization occurred. If you test glycol by this test or any variation which includes drying at over 100 C., in a completely dry atmosphere you will not see any stabilization because the glycol will all be evaporated. Wood articles in common use are always in an atmosphere containing some water, however, and under such conditions, glycol will not evaporate.
Even after I had obtained encouraging results in the stabilization of wood with glycol, I was concerned about the permanence of the treatment. Glycol has a vapor pressure of about 0.1mm of mercury at room temperature. This is very low, but I set out to determine how rapidly glycol would evaporate by exposing a shallow pan of glycol in my shop and weighing it at intervals. Instead of losing weight, the pan gained weight rapidly until the weight of liquid in the pan was about 75% more than at the start; the glycol was rapidly absorbing water from the air, not evaporating. Some literature search turned up the interesting items that glycol has been used to dehumidify air in air conditioning systems and a test of glycol as a laboratory dessicant (drying agent) which showed it as effective as 100% sulfuric acid and phosphorus pentoxide, two of the most common dessicants.
In 1978, I cut one-inch thick slabs from a 4-inch diameter green black locust log and soaked them in glycol for four days at room temperature or at about 200 F. for four hours in a slow cooker pot. I laid them out in the sun along with untreated controls; the controls cracked badly in a couple of days while the treated samples were sound after two weeks.
In 1981, my wife was carving a wood sculpture of red cedar. Her instructor told her if she kept it wet with antifreeze it would not crack. This rekindled my interest in stabilizing wood with glycol and I have carried out a variety of experiments and practical test which demonstrate that antifreeze is a very effective treatment for stabilizing wood.
I ran comparative tests of undiluted glycol, 40% sugar solution, and 50% PEG-1000 solution on one-inch thick slabs cut from freshly-cut longleaf yellow pine and live oak logs. Untreated controls were compared with samples soaked in antifreeze, 50% PEG-1000 solution, and 40% cane sugar solution. The untreated controls cracked radially; esp., the live oak pieces. All three kinds of treated samples stayed sound. From the same logs I cut pairs of 9" billets; one control and one treated with glycol by standing on end in a shallow pan of antifreeze and turning end for end for 16 days. The billets then air-dried for 4 1/2 months before they were photographed. Figure 1 shows the live oak samples. The untreated piece on the left is badly cracked and has shrunk so that the bark is coming loose. The treated piece is sound with tight bark; the rays are quite prominent. In Figure 2, the untreated pine on the left has two prominent cracks and a network of finer ones over the whole end; the wood has shrunk so that the bark is very loose. The treated pine has no cracks at all and the bark is tight, indicating no significant shrinkage. The photographs of Figure 3 show another effect of antifreeze on dried wood. A billet of live oak on my wood pile had been drying for about a year and both ends were badly cracked. After standing on end in a shallow pan of antifreeze for a month, I cut the billet in half for simultaneous photographing of the ends. The treated end has its cracks closed nearly completely; originally it looked like the untreated end.
I cut 3" by 1" by 1" pieces longitudinally, radially, and tangentially from a live longleaf pine log. The samples were treated with glycol by painting them 3-4 times with antifreeze; they air-dried to stable weights in about six weeks with no shrinkage. Untreated controls dried in about two weeks and shrank 2% radially and 3% tangentially.
A common woodworking problem is cupping of boards. Thin mahogany (3/8") I had planed for a table shelf cupped badly. I painted the concave surface with antifreeze and the next morning the board was flat; glued up into the shelf it is still flat three years later.
A 26' reproduction surfboat at New Hanover County Museum was taken out of the water and put in dry inside storage. Within two months all of the lapstrake planking joints had opened, as shown by the broken paint film on the outside. The curator agreed to my suggestion that I treat it with antifreeze. The boat had an oil finish inside and oil-based enamel outside. I loaded a garden sprayer with antifreeze and wet down the inside. Every plank joint dripped on the floor. After three more treatments 1-2 weeks apart, not a joint leaked and all of the breaks in the outside paint had disappeared as the juniper boards swelled back together. I was surprised that less than two gallons of antifreeze were needed for the successful treatment. The boat has stayed tight for over two years. If we put the boat back in the water, the glycol will probably leach out fairly rapidly and we would have to retreat the boat. After I reported this at the Small Craft Curators Conference in 1986, George Surgent at Calvert Maritime Museum reported that he had used antifreeze to swell hull planking.
Going from boats to archaeology, Leslie Bright at the North Carolina Underwater Archeology Unit gave me a musket butt recovered from a Civil War blockade runner. The century-plus old piece had been stored in a tank of fresh water since it came out of the sea. I soaked it in antifreeze for three months and then let it air dry. Without treatment it would have fallen apart on drying, but my piece was in the same condition as when I got it; even the tool marks where a metal plate had benn inlet were still intact.
My dining room chair squeaked with every fork motion. My wife said I should fix all of the chairs. I took them out to the shop, set them upside down and used a dropper to put antifreeze in every joint. By the next morning they were tight. Some time later a syndicated newspaper columnist (Bruce Johnson, "Knock on Wood") wrote that products advertised to tighten chair joints do not work because they are mostly water. I wrote him and suggested he try antifreeze. A later column reported that my suggestion worked.
Recently a local lumber company had a sale to clear out their leftover half whiskey barrel planters. I brought three home which had dried out so that the staves were rattling. I sprayed the insides and the end grain exposed on the tops with antifreeze. The next morning they were all tight enough so that they no longer rattled and in a couple of days you could not get a knife blade through any of the joints. They could have held Jack Daniels again.
In the fall of 1986, I had some yellow pine plywood sheets that had been used outside for lofting a boat; they had two coats of white latex house paint on them and had checked badly. I cut two adjacent pieces and treated one by painting it with antifreeze a couple of times; all of its checks closed up and are still tight.
I have collected experiences with antifreeze from others. Bob Pickett, Flounder Bay Boat Lumber, Anacortes, WA, wrote me that they use antifreeze to prevent checking on the flat grain surfaces of large fir timbers. James Marsh, Marblehead, MA, wrote in Small Boat Journal that he carved a large dugout canoe from a cottonwood log and used antifreeze to prevent cracking. I asked him for details and he also told me he had heard of elm slabs in Maine kept from cracking with antifreeze and walnut baulks for gunstocks treated with antifreeze in Massachusetts during World War II. In Haines, AK, in 1987 I asked an Indian carver of totem poles if he had ever considered using antifreeze to prevent cracking; he told me he knew it would work, but preferred to let his work crack naturally. When I told the boatbuilder who built the surfboat mentioned above what I had done to his creation, he said that explained why he had seen large redwood slabs being soaked in a tank of antifreeze in California in the 1960s.
Though Stamm neglected glycerol, there has been interesting work with it by others. Leffingwell and Lesser reported in 1941 that undiluted glycerol was being used commercially in the furniture industry to flexibilize and stabilize veneers and as an additive to water-based glues to prevent their drying out; the authors recognized that glycerol (like glycol) was effective because it is very hygroscopic and does not evaporate. In 1968, Pankevicius in Australia tested glycerol and PEGs with molecular weights of 200, 555, and 1000 for stabilizing five varieties of Australian timbers. He got significantly better results with glycerol in all his tests and concluded "Glycerol, having the lowest molecular weight, has proved to be the best dimensional stabilizer." (Glycol is even lower.)
Glycol antifreeze is best used undiluted; it acts more rapidly and no subsequent drying step is needed. Not only can glycol be used on dry wood, but it can penetrate many finishes without damaging them. I have treated pieces that were finished with oil, oil-based enamel, latex paint, spar varnish, or lacquer without staining or lifting the finish. Glycol does not penetrate polyurethane or epoxy coatings. The dyes in antifreeze are so weak that they do not discolor even the lightest colored wood. I started out soaking pieces as you would for peg, but that is generally more treatment than is needed. I spray or paint the antifreeze on with special attention to the end grain. Once the piece is dry to touch, it can be glued or finished.
Glycol antifreeze is toxic if taken internally; animals like its sweet taste, so do not leave it out for them or children to get into. I use only coarse sprays to avoid inhaling fine mists.
Try antifreeze for all your problems with wood motion. Paint it on the concave surfaces of cupped boards. Use a medicine dropper to get it into loose joints, For a cracked panel, remember that the crack occurred because the whole panel shrank, so paint the whole surface on both sides. Dip, paint, or spray a pieces you are carving or turning to prevent cracking, or to cure cracks which have already occurred. Keep your antifreeze in closed containers to avoid picking up water from the atmosphere and slowing down the action. As in any other process with as many variables, each problem is different and you may have to experiment to get the optimum treatment. Pass on your experiences so that we all can learn from them.
David W. Carnell
322 Pages Creek Drive
Wilmington, NC 28411 July 21, 1989
