Newsletter November 9, 2002

The time has come to finish the faux crackle finish. I imagine that a lot of you have forged ahead and have completed the project and have a nice crackle finish already. Our finish material to review this time is shellac. We've got information about how to cure sticking drawers and sticking fingers, as well as repairing chair joints and some more bits and pieces.

Email question

I would like to know what you consider a good glue to re-glue my chairs. The chairs have started to come apart due to their constant use. They do not have rollers on them, so my husband tells me that when someone scoots the chairs back that that process causes the glue to come apart. We have some "old" chairs that we have glued and they come apart. How do you take care of this.

Our dining room table is used every day, is over 100 years old, we need to reglue the chairs and put new fabric on the seats.

Thank You

Helen

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Reply

A yellow woodworking glue is best. The yellow glue is an aliphatic hydrocarbon glue. I read somewhere years ago that the molecules of the aliphatic hydrocarbon glue are shaped like little coil springs and they screw into each other and actually screw into the pores of the wood. The yellow glue will generally make a stronger bond than the wood around it.

Don't use glue gun glue, it's flexible and fills gaps, so if you get some at the end of the rung or tenon it won't permit the joint to go completely together and the joint will never be solid, because of the flexibility of the glue.

When you separate the joints, clean as much old glue out as you can, being very careful not to remove any wood. If wood is removed from the hole it will become larger, or if wood is removed from the rung or tenon it will make it smaller and cause the joint to be more loose.

Your husband is correct about the scooting the chairs making the joints loosen, especially on carpeting. Each time a chair is scooted the cells of the wood in the joint are compressed a little and after 100 years can be quite compressed. If the end of a rung is shiney, it's generally due to compression.

When you open the joints up pour boiling water in the hole and put the rung ends or tenons on end in a pan of boiling hot water, just enough to cover the raw wood ends, but not on the finished portion of the wood. You may have to make several applications of boiling water, but the cells of the wood which haven't been broken open should pop back out to their normal position. Let the wood dry completely and it should have swelled enough for a tight fit and with new glue should last quite a while before you have to repair again.

Assemble all of the lower joints at the same time and work on a flat surface like a table top to be sure that all joints are together equally to make all four legs make contact.

Clamping is necessary when repairing chair joints, or any other joint where something goes into a hole where there isn't any place for air to escape. A rung or tenon will act as a piston, compressing the air at the end, then the air will push the joint back out, but if it's clamped the air will slowly find it's way out. If you don't have regular clamps, use some rope or heavy twine wrapped around opposing legs. Leave a little slack in the rope and put a stick or pencil between the two sections of rope and twist the rope until it's tight and the chair joint is securely pulled together. Be sure to work on a flat surface.

Even though the glue bottle will probably say that the glue will set up in an hour, leave the joint clamped for at least 12 hours to let it cure and it will make a more secure joint.

If you end up with a chair that rocks on two legs, even though you took precautions, don't try to cut one leg off a little to even it up, add a glide to one of the shorter legs to make them even. If you use nylon glides you can sand them down a little if they're too long. Cutting a leg down never seems to work and after you've cut each leg several times you will usually end up with a very short chair that rocks on two legs.

We left off with the application of the base coat which should be pretty dry by now. You should give the base coat a light sanding to give the crackling medium a better chance to stick.

We'll just cover glue as a crackling medium, since the crackling kits and other commercial crackling medium have their own specific instruction with the product.

If you're using the old traditional glue pot and hide glue, now is the time to put the clothespin on your nose and heat the glue to spreading consistency. If you're using liquid hide glue let it sit in a bowl of warm water until it's thin enough to brush and if you're using white glue thin it with enough warm water to make it a good brushing consistency.

Brush the glue over the base coat. Try not to overbrush as the glue will start to form a skin as soon as it's exposed to the air and it might bunch up rather than spreading smoothly. If you brush the glue just back and forth in one direction the cracks will form in the same manner, but if you brush the glue randomly in all directions the cracks will form the same way in a random pattern. Let the glue dry thoroughly.

Next comes the top coat, which should be a water base paint. Latex paint is flexible and may not give the result you want, unless you're using a kit that specifically calls for latex paint.

Apply the paint with one stroke only, because it will soften the glue coat and if you overbrush you might remove the glue in places, so be sure to have plenty of paint in your brush. A heavy top coat will give larger cracks and a thin coat will give more delicate cracks.

The top coat of paint will soften the glue coat, then when paint and glue dry and cure they do it at a different rate which causes the cracking and separating of the top coat of paint.

To give an aged appearance to your crackle, let the whole thing dry thoroughly, at least overnight, then give an overwash of stain which has been thinned by about half. Remove the excess stain and let it dry.

The faux crackle finish will be kind of fragile in its natural state so it should be sealed with an oil base sealer to give it some protection. You can choose from satin, matte or gloss sealer, whichever effect you desire to have.

Next newsletter we'll have a different faux finish, but it's still undecided which one, since we're still receiving feedback with requests.

Our installment on finishes, paints and stains this time is about shellac.

Shellac is a natural element and as is generally the case with natural things, it's uses are almost unlimited. It is used pharmaceutically and in the food industry as well as a furniture finish.

M and M's used to be coated with shellac to make them firm and shiney.

DO NOT and I repeat, DO NOT use the shellac that you buy at the paint store to shine up your cinnamon rolls or something edible shellac is processed different than finish shellac.

Shellac has been around since a couple of centuries after the birth of Christ, but it was originally processed for the dye color and some time later someone discovered, lo and behold, that it would make a good finish for furniture.

Shellac is a secretion, called lac, from a little bug that sucks sap from trees indiginous to India and Thailand, then secrets the resinous substance which is processed to make shellac in it's various forms.

Shellac was a very popular furniture finish until the mid 1800's when someone came up with lacquer made from nitrocellulose. Shellac is hard, but fragile around water and it's dissolved by alcohol.

Wealthy people in bygone times would have french polishers come in once a year and french polish their furniture and shellac is the main ingredient in french polish. We'll cover french polish in another newsletter.

Shellac is a good finish still used by lots of craftsmen and is a must when restoring an antique that originally had a shellac finish.

It's always handy to have a good assortment of Dowel Pins handy when you're working on furniture. For who knows what reason dowel pins will break inside a joint and to have a good secure joint that will be trouble free for many years you will need to replace the broken pins. Lots of modern day joints are assembled with Biscuits, but I think dowel pins will always be with us.