Repair advice on 18th Cent piece...

[Dan Carroll]

I have been asked by a family member to repair this 18th Cent. South Carolina back woods table. I have questions about the screws used to attache the top. How do you ID 18th screws? I am using hide glue to fix the crack in the top. I am wondering about reattaching the top to the base. Should I open up the holes to allow expanision? SOme other method? If I just put the top back on with the existing screws, the top is going to crack again. Any advise or insights?

[george wilson]

Genuine 18th.C. screws have no points. Their ends are just forged off. The threads may be straight and not tapered. They were making screws on lathes that also cut the threads even in the 18th.C. in England. When the American Revolution broke out,the warehouses of the screw makers were very overstocked. The threading was done by dies which were attached to the lathes,rather than cut by leadscrews as modern lathes do.

Is that a tongue and groove joint? You could plug the screw holes on 1 side of the table and re locate them. Be sure to make the holes as large as the root diameter of the screws IF they are original,and have no points. Actually,you should do that in any case.

Hide glue is the way to go. It is reversible .

[Dan Carroll]

I think the screw were later. I will post some pictures, but they are tapered and look like they were just cut off on the end. There is evidence of pegs through the top and into the cleats. I will try to get some pictures. I have a feeling that some work has been done on this piece in say the 1950's or so by someone that had no idea what to do with it.

[Dan Carroll]

Here some pictures of the screws and the base a bit closer in. I have glued the top with hide glue.

[george wilson]

Those look authentic,except for the 2 pointed ones. Another thing to look for is off center slots where they were hand sawn. Those seem better than usual in that sense.

The way to tell wrought iron from steel is to file a spot bright. Put a drop of nitric acid on it. It will turn the metal gray if it's wrought iron,and brown if it's mild steel(or any carbon steel).

The heads of those screws are also different in diameter,though they seem to be the same size screw. That is from being hand cut off. I think they're real. I didn't mean to say they NEVER have taper.

[Dan Carroll]

Wish I could get better, clearer pictures to post. Sorry for the poor quality. The shinny spots on the end of the screws almost look like they have been cut off to me. I will see is I can locate some nitric acid and do the test you suggest.

[george wilson]

You seem to have the same problem as I do. Holding the camera still while you push that button. I wish the button on my little Canon wasn't so hard to push. I have posted plenty of bad pictures,but am going to use the tripod more often.:)

[Joseph Klosek]

Here is a study on wood screws from the MFA in Boston.

In regards to the table, the legs look a little odd. They look like rather crude replacements.

Are you going to try and remedy that as well?

http://cool.conservation-us.org/coolaic/sg/wag/Am_Wood_Screws.pdf

[george wilson]

The study you refer to is pretty lax in describing types of metal. It mentions STEEL where it should use Wrought iron,or at least iron. It mentions all steel lathes where it should say cast iron lathes. The cutting head has more the form of a die than the usual single point threading tool.

Probably written by weenies with insufficient knowledge of metals.

[Dan Carroll]

I don't think they are replacements. If they are they are pretty old replacements. Like I said, this was a back county table. My cousin can ID the maker, a farmer ancester that was pretty unskilled as a furniture maker. It could also have been a slave maker, but there is no indication any of his slaves had furniture making skills. He was also the sheriff of the county in the 1780's/1790's and likely saw something like it in Charleston and this was his attempt to make one for his home. (A two story log house) The legs are made of chestnut and have a bridle joint rather than a sliding dovetail. There is not indication that it ever had anything other than the 4 legs. The column looks to be out of pine and the top poplar. On the bottom of the top where the column plate (sp) rests it almost looks like it had a red wash of some kind on it.

[Joseph Klosek]

George,

I thought the visual clues mentioned were helpful for someone who may not have any metallurgy experience. The nitric acid test is good advise, however I am sure the conservator(weenies) would cringe. I will have to use that tip.

[Joseph Klosek]

Dan,

It looked as if there was some sort of glue staining(finish missing) where the legs go into the column. That is what made me think they could be replacements. It is pretty suprising that the bottom of the column is not all busted up with the legs going all the way through like they do.

Is the top 2 boards? The tongue and groove joint may not have been glued when it was made. Maybe the guy just nailed it to the stretchers and called it good. Then the screws were added later.

[george wilson]

They might cringe,having been around them for 39 years. But,they would have to use a test themselves if necessary. It is still only a screw,though,and there are plenty of them around. Not the same as refinishing a piece of furniture.

An extreme case of "Weennieism" ( a word I made up!:): They got an 18th.C. rifle whose barrel had fallen off,and was tied on with some GROCERY STRING. The particular curator wanted to leave the string(modern string) ON the gun "Because the string was part of its history!" The Master gunsmith laughingly related that story to me.

[Joseph Klosek]

Did you catch the part at the end of the report where the author stated that he ground a screwdriver to fit the slots exactly before removing the screws?

Was the gunsmith able to remove the string using appropriate techniques and replace it without any alteration?

I'm sure you could write another 4000 posts about conservators after dealing with them for close to 40 years.

[george wilson]

If the conservator knew enough to buy a set of Brownell's gunsmith screwdrivers,which come with MANY tips,he would not have had to resort to grinding them.

I did manage to introduce some beneficial technology to the furniture conservators,as well as learning from them.
I don't know how the string thing ever worked out.

Anther curator laid a very valuable rifle on TOP of his car. He had gone several blocks,and around some corners before he remembered that the rifle was STILL on top of his car. It was worth mid 5 figures in the 1980's.

[Erik Manchester]

George,

That kills me, but it sounds so true! Pity there wasn't a picture of the individuals face at the moment he realized the gun was (hopefully) still on top of he car :):)

Erik

[harry strasil]

I sincerely hope you marked which screw went where, it looks to my eye that they are a tad different in lengths as hand made screws and nails tend to be.

I learned the hard way to mark which saw handle screw went where and to make sure I screwed the mating nut onto its screw, when removing old saw handles to work on the plates.

[george wilson]

Yes,Probably too late,but at least try to feel when you hit the bottom of the hole and not force a long screw into a short hole.

Actually,I've changed my mind. I think Harry made those screws when he was young.:):):)

Truth is,Harry is younger than me.

P.S.,Harry,did you use the knurl yet?

[harry strasil]

Not yet George, I have to make a mounting for it first.

BTW, a few years ago at the request of a local upholster/furniture restorer friend, who has done quite a few restorations for our state capital, and also been asked to bid some work for the Smithsonian, asked me to make some replacement old style screws for a piece he was working on. After I inspected several of the original screws, I determined that they were hand forged and the threads were filed in. I made a set of swages and a header to forge the screws and used my little antique hand vise to hold them while I filed in the threads. I now know why the hardware of old days was so expensive. Luckily I only had to make 3 of the screws. The filing lessons I did during my apprenticeship paid off big time on that job.

Jr.

FWIW, our guild is having a fun raising benefit auction on Nov 6 at the guild shop and is open to the public, hopefully we will make enough to pay the rent on the large shop shared by the KC Woodworkers Guild/KC Wood Turners Club.

A partial list of items to be auctioned can be found at: http://www.kcwoodworkersguild.org/Auction%20Items.pdf with pictures of many items at:
http://www.kcwoodworkersguild.org/Auction.htm

[Derby Matthews]

To check for screw composition you can just touch it to a grinding wheel. Wrought Iron sparks will fly more or less in a fan shaped straight line, where mild steel sparks will "fork" into smaller bursts near the grinding wheel. The rule of thumb is that the closer to the wheel the sparks fork, the higher the carbon content of the steel. No Nitric acid is needed. The stuff is hard to store long-term safely anyway. It eats thru everything, including glass.

The screws used to make an early 18th century piece are easy to identify by comparing the the fineness depth, and lack of uniformity of the threads and slot compared to a more modern screw, which will have a coarser pitch, shallower and "flatter" minor diameter (not as vee shaped at the bottom), and thinner minor diameter/ major diameter ratio (the threads are deeper). The driving slot will also be narrower and deeper on an earlier screw.

Tea tables, candlestands and particularly tilt top tables almost always had screws connecting the battens to the underside of the top surface. It is very rare to see early ones connected with a sliding dovetail, and they are almost never simply glued. I've never even seen one myself. I expect any tables built that way would surely have stoked a fire a long time ago.

A split in the top is either a failing glue joint (newer revival tables with two or three-board tops) or checking, most likely started by one of the screws creating too much tension when the top contracted across it's grain as it aged. There's always a tug of war between the battens and the top. The battens almost always win. 'Ovaling' the screw holes and countersinks in the battens will relieve this tension without harming value in all but a curator's (or The Keno Brothers') mind (see above post for previous anecdotes on "weenieism")
A partial split can be left alone if the battens are well attached, with at least two screws in each of both halves. If not, then a partial can be correctly repaired with a butterfly if it cannot be coaxed closed and simply glued with hide glue. If it's a joint that has failed then it must be carefully cleaned and re-glued, taking care to register the top surface as well as you can. Inexperienced clamping of these glue ups can result in excessive cursing.

I've been a professional conservator / restorer since 1981, and have worked for Sotheby's in New York. Best to always follow the rule "less is more".PM me with any questions. Hope the above helps.

[george wilson]

I thought the acid test would be less destructive than a spark test. Threads cut on a lathe in the 18th.C. would still be uniform. They were mass produced even then,if you read the posts above,and the references.

[Derby Matthews]

One need only touch the tip of the screw to the grinding wheel. You have to remove oxidation anyway to get a new surface to acid test. This test eliminates that step.

Early screws are uniformly made as you say George, only noticably less so than those made on "modern" screw-making equipment. To a point, that is. Today's typical cad-plated wood screws have become more and more sloppily made (Chinafied) in recent decades. Guess you turn up the speed on the machine too much and they start looking like They came from an episode of "I love Lucy"...:D


To clarify, I should say that only true hand-filed screws from very early Continental/ British makers and later Colonial homemade / country pieces would be obviously non-uniform to a casual observer. We Americans have been making store-bought wrought nails since before the war of 1812, but I don't know when machine made screws first became widely available on this side of the pond.

[george wilson]

If you read my initial post,the company that was making them in England suffered a glut of screws in their warehouse after the revolution started. There is no doubt that country gunsmiths or other rural craftsmen filed their own screws out,though. They still file out their butt plate wooden screws in Colonial Williamsburg,along with all the other screws.

I have a large # of 1950's vintage wood screws. I bought out an OLD ship fitting co's. stock of wood screws at their closing down auction. Must have been 2000# of them.

They are SO much better than newer ones. They have sharp,not stamped threads,sharp edges on their heads,and sharp,sawn,not punched slots.

[harry strasil]

If I might correct you just a bit George, the screw slots are not sawn but milled. I have several of the thin milling cutters I got surplus, they do come in handy.

We think alike again, many years ago my main supplier was closing out their stock of rivets, I saw the writing on the wall and bought 500#'s of various sizes. Now they are very hard to find and people still come and ask me if I have a certain size of rivet. The same with the various and many different styles of plow bolts. I still have a decent supply, because I bought when they were being closed out by my suppliers. It turned out to be a good investment as the rivets and plow bolts are worth a lot more than even considering inflation and COL. I don't scalp people, just get what the going price is now.

[george wilson]

I meant sawn with thin milling type saws. That isn't sawn? Maybe milled 1/32" wide.

[Dan Carroll]

To check for screw composition you can just touch it to a grinding wheel. Wrought Iron sparks will fly more or less in a fan shaped straight line, where mild steel sparks will "fork" into smaller bursts near the grinding wheel. The rule of thumb is that the closer to the wheel the sparks fork, the higher the carbon content of the steel. No Nitric acid is needed. The stuff is hard to store long-term safely anyway. It eats thru everything, including glass.

The screws used to make an early 18th century piece are easy to identify by comparing the the fineness depth, and lack of uniformity of the threads and slot compared to a more modern screw, which will have a coarser pitch, shallower and "flatter" minor diameter (not as vee shaped at the bottom), and thinner minor diameter/ major diameter ratio (the threads are deeper). The driving slot will also be narrower and deeper on an earlier screw.

Tea tables, candlestands and particularly tilt top tables almost always had screws connecting the battens to the underside of the top surface. It is very rare to see early ones connected with a sliding dovetail, and they are almost never simply glued. I've never even seen one myself. I expect any tables built that way would surely have stoked a fire a long time ago.

A split in the top is either a failing glue joint (newer revival tables with two or three-board tops) or checking, most likely started by one of the screws creating too much tension when the top contracted across it's grain as it aged. There's always a tug of war between the battens and the top. The battens almost always win. 'Ovaling' the screw holes and countersinks in the battens will relieve this tension without harming value in all but a curator's (or The Keno Brothers') mind (see above post for previous anecdotes on "weenieism")
A partial split can be left alone if the battens are well attached, with at least two screws in each of both halves. If not, then a partial can be correctly repaired with a butterfly if it cannot be coaxed closed and simply glued with hide glue. If it's a joint that has failed then it must be carefully cleaned and re-glued, taking care to register the top surface as well as you can. Inexperienced clamping of these glue ups can result in excessive cursing.

I've been a professional conservator / restorer since 1981, and have worked for Sotheby's in New York. Best to always follow the rule "less is more".PM me with any questions. Hope the above helps.


I have got to top reglued without too much cursing!! The split opened up when the piece was moved from an unair conditioned house in Georgia to an apartment in Conn. It was dammaged in shipping. I cleaned up an much of the old glue as I could without impacting the surface. I used cull, clamps and bench dogs/ end vise on my work bench to get enough clamping force / hold down. Since it is going to live in up north of the Mason-Dixon and deal with greater changes in humidity than in the past, my concerns are more about keeping it from splitting again and doing injury to itself. I am thinking that the oveling as you say is the way to go.

[george wilson]

By the way,Southern furniture is relatively rare. Your table may have some extra value. You should conserve it with absolutely as few alterations as possible. Leave the original finish,too. Get a museum to look at it.

[Joseph Klosek]

Dan,

Is it possible to just put the screws back in the center and then loosely place the screws on the outside to allow for some movement. You may not need to change the size of the holes in the cleats that way. Also, there may be enough room in the holes that has occured over time.

It is hard to tell from the photos. Only you will know from having the piece in front of you.

I have glued together many tops like this with the same malady and put the screws back in the same holes with no issues. I am in central VA and the humidity swings widely here as well. I know of one cherry tilt top table that I repaired about 5 years ago and is still holding up.

Does the top sit flat on the cleats?

J.P.

[Derby Matthews]

If the shank holes are better than a one and a half the diameter of the screw shank I agree, no further widening should be necessary. Leaving the screws loose would bother me in that every time the table is lifted or moved it would permit shifting which almost always leads to eventual further loosening. It also invites warping, something the battens were designed to prevent in the first place. If indicated, precautionary ovaling of the shank holes in the batten can be done in a few minutes with a rat tail file. It's best to make the hole almost more of a slot (parallel the the sides of the batten!) at the surface where the batten mates with the table top. This allows the screw shank to "swing" minutely from the countersunk head with any expansion or contraction of the top. You don't really have to do anything to the countersunk (or counterbored) screw head area in the batten as long as the shank hole is relieved. When done this way and reassembled, not even a curator can tell the shank hole has been relaxed without taking the table apart again. Something no curator would dare do without lots of paperwork first.:D

I should add that shortening the screws a tiny bit by tipping them off on a grinder also helps prevent the dreaded " screw-tip eruption" AKA "blow-thru" or" OH-NO-MOMENT! :~O" on the top surface when reassembling the table. That alone would ruin your whole day.

[Dan Carroll]

Funny, i was thinking of using a rat tail fle and just getting a little extra play. I like the idea of going from the side where the cleat meets the to and doing them at a bit of an angle so it would not be visable from the underside of the table. I think I can make the take a thin straw and measure the holes to match up the screws to the holes they came from. Would you suggest a little wax to help the movement of the screws in the holes?

[Derby Matthews]

You can, just don't use soap. It will corrode the screws. I rub the screws against an old candle then put them in, being careful not to over-pressure them when tightening that last turn (that dreaded blow-thru issue) also make sure all any crap is out of the bottom of the screw holes before you install (same reason). Good luck, and hope my experiences - gained over decades of remembered frightening mishaps - helps