Moulthrop Family Bowl Finish and Techniques – What do you know?

[Tony Maness]

Ed Moulthrop (1916-2003) was a self-taught wood turner, known as the "father of modern woodturning". ... He was most famous for his large scale turned bowls, made from domestic woods, usually spherical or elliptical with polished clear finishes. The finishes the Moulthrop’s use are what I am requesting the AAW bowl turning community to share their insights on. Please watch the attached video link below on the Moultroup’s bowl turning legacy an techniques. Focus on frames after the 2:30 minute mark. I am assuming that the finish is standard epoxy but how do they control the viscosity and clarity. Also shown in the video is the family’s design of a drying apparatus. Does anyone have a smaller version of the apparatus. The quick release system from the lathe and attachment to the drying machine is unique in itself. Share what you know or can deduce from the video.

Moulthrop video link: http://youtu.be/cj5pg7B5VWg

 

[Joe Greiner]

See post #7 here: http://www.aawforum.org/vbforum/showthread.php?8905-wanting-slow-rpm&highlight=rotisserie

I have another one, stand alone, with a variety of workholding devices for unusual shapes.

 

[odie]

I was aware of, and read about Ed Moulthrop's works long before his son took over the family tradition.......

You are probably going to find that not many, if anyone outside of the Moulthrop family know all the fine details of the techniques Ed Moulthrop used. Trade secrets are what keeps all the copycats from doing what the technique originators do, and most turners who have developed a distinctive style are not going to freely tell everyone everything about the technical aspects of what determines their individuality. After watching the video, I can only make some educated guesses as to the total Moulthrop technique.

Is it plain ol' epoxy? That would be my guess, as well. Could have other ingredients added, but the consistency looks like honey, and this is what normal epoxy consistency is. If there is something added to control viscosity, then it would be to thin the epoxy.....but, I doubt anything is added. You can see that heat from a propane torch is used, and this can only be used to increase viscosity as the epoxy hardens, or control the rate of drying.

The slow spin rack looks like it can hold a maximum of 22 bowls, but the very big bowl is done as an individual bowl. This process likely means the operator will have to be present and monitoring the progress during the entire operation......which is probably several hours, or more. Looks like it requires constant concentrated attention for this step. My guess why the bowls are spinning on their side, is because the gravity pull will be alternating, whereas it would not with the bowl standing normally. This does make theoretical sense, in that epoxy does respond to gravity, for the first few hours of the set-up time.

The Moulthrops are obviously faceplate turners, and the faceplates remain on the turning until after the final finish is applied. I've never seen the bottom of one of Ed Moulthrop's bowls.....would be interesting to see how the screw holes are addressed. The stockpile of faceplates must be......lots of them!

ooc

 

[Gerald Lawrence]

Air bubbles

I was aware of, and read about Ed Moulthrop's works long before his son took over the family tradition.......


Is it plain ol' epoxy? That would be my guess, as well. Could have other ingredients added, but the consistency looks like honey, and this is what normal epoxy consistency is. If there is something added to control viscosity, then it would be to thin the epoxy.....but, I doubt anything is added. You can see that heat from a propane torch is used, and this can only be used to increase viscosity as the epoxy hardens, or control the rate of drying.


ooc

I believe that the heat is used to reduce the number or totally remove bubbleds from the epoxy. This is a technique used for bar top finish to remove the air bubbles common in this type of finish. Takes a lot of practice to get proficient at it from what I have read.

 

[odie]

I believe that the heat is used to reduce the number or totally remove bubbleds from the epoxy. This is a technique used for bar top finish to remove the air bubbles common in this type of finish. Takes a lot of practice to get proficient at it from what I have read.

Hello Gerald......Does the use of heat prevent the bubbles from forming, or does heat allow the bubbles to come to the surface and expel into the atmosphere? If it is the latter, then wouldn't this be because the epoxy is more fluid......or an increase in viscosity? If the fluidity of the epoxy is increased, then wouldn't that apply to the theory of using heat to influence viscosity, in context?

I don't know the answers here......just throwing the thought out there for discussion, or for those who do know the answer, to respond.

ooc

 

[Richard Findley]

I watched the video with interest. A couple of things jumped out at me, although nothing that answers the op's questions I'm afraid.

Firstly, that lathe looks way too low. I suppose it means you don't have o lift those monsterous lumps of wood so high, but doesn't seem all that comfortable as far as turning is concerned.

The other thing that drew my attention was the pin in the tool rest. Again, I can kind of see its use with massive chunks of wood but the item on the lathe in the video seemed pretty standard, dimensionally. I'm no hollow form turner, I'm primarily a spindle turner, but having to use the pin as a lever seems like poor technique, which seems strange considering the heritage and family history.

Please don't think I'm criticising or being judgemental, I'm genuinely interested in the use of techniques etc.

Looking forward to your responses.

Richard

 

[KellyDunn]

If I recall he used a product called PEG.
However it began to break down after many years.
He used a tool he called a lance to turn with. Photos show him with it about hip high. There are better ways these days but he did what he did all by himself. I forget who brought all these hermit turners together. Heard stories about these guys working by themselves and hunted them up. Lecoff? Nish?
His bowls were very shiny. I have not seen one with the finish breaking down but have been told all of them are doing so. I could be wrong.

 

[Tony Maness]

The Link below leads you to a .pdf file on "Adhesion Problems and Degradation of Epoxy
Finishes on Peg Treated Wood"


http://cool.conservation-us.org/coolaic/sg/wag/2006/pine_06.pdf


I also viewed a video of Matt Moulthrop stating that he could adjust the finish to cure in 7 minutes or 7 days. That statement is what prompted my forum discussion. The link is below. The statements is made at frame time 13:30
minutes

link: http://video.pbs.org/video/2152205235/

 

[stu senator]

Bubbles??

The air bubbles are a function of the mixing of the two parts of the resin. I used to "Pot" electronics (seal it in a blob of resin) to protect it and make it difficult to copy. To remove the air we used a vacuum chamber on the mixture. It could then be pushed by air pressure to the chamber with the electronics. Alternately we could pour it but it had to be in a thin stream slowly to allow any air entrapped to escape.

The video shows him pouring and brushing it on. Applying heat is a delicate balance between speeding up the cure and making the resin thiner or more flowable allowing the air to leave.

The PEG was used to reduce the moisture (or replace the moisture) in the wood and get rid of the drying and warping problem. I understand that it made the finishing difficult (and imparted a waxy feeling to the wood) hence the epoxy finish. Do not know any more about this as I never used it, just read about it.

Stu

 

[Gerald Lawrence]

Hello Gerald......Does the use of heat prevent the bubbles from forming, or does heat allow the bubbles to come to the surface and expel into the atmosphere? If it is the latter, then wouldn't this be because the epoxy is more fluid......or an increase in viscosity? If the fluidity of the epoxy is increased, then wouldn't that apply to the theory of using heat to influence viscosity, in context?

I don't know the answers here......just throwing the thought out there for discussion, or for those who do know the answer, to respond.

ooc

Only a guess on my part. Simple chemistry says that gases expand when heated, :therefore (hey that is the way we did the thorium in school) the heat expands the gas and causes it to rise to the surface. I do not know if heat also thins epoxy. I would think that the heat would cause the cure rate to speed up at least marginally as colder temps do slow down cure of most glues and finishes.

 

[bowlman]

The other thing that drew my attention was the pin in the tool rest. Again, I can kind of see its use with massive chunks of wood but the item on the lathe in the video seemed pretty standard, dimensionally. I'm no hollow form turner, I'm primarily a spindle turner, but having to use the pin as a lever seems like poor technique, which seems strange considering the heritage and family history.

Richard

Richard, I met Ed Moulthrop at Arrowmont in 1985 and subsequently visited him in Georgia several times. I even purchased a lance and some other tools. The pin in the tool rest is absolutely essential when using the lance ... provided you want controlled cuts. Back then I was 265 pounds of muscle and bone (and some fat too), and I was fearless and foolhardy when it came to anything dealing with woodturning. There was no way I could perform a controlled accurate cut without the pin ... and man, did I ever try! The lance really had no bevel as we would know it, so nothing to help you guide the cut. The lance just had the rounded shape from the bar from which it was made. That being said, yes, some 30 years later there are probably better ways to do the same thing and better tools, BUT, Ed was a pioneer and made everything he could rather than purchase it. His favorite hardware store/turning outfitter was a local salvage yard. His faceplates were latge toothed gears. He bolted them to the wood using lag screws. Nick Cook knew him better than I did (I Think) ... perhaps he will chime in.

Hope this helps shed some light on his poor technique.

 

[Tony Maness]

See post #7 here: http://www.aawforum.org/vbforum/showthread.php?8905-wanting-slow-rpm&highlight=rotisserie

I have another one, stand alone, with a variety of workholding devices for unusual shapes.

Thanks. Looks like there are ways to mount a slow RPM motor to a lathe.

 

[Richard Findley]

Richard, I met Ed Moulthrop at Arrowmont in 1985 and subsequently visited him in Georgia several times. I even purchased a lance and some other tools. The pin in the tool rest is absolutely essential when using the lance ... provided you want controlled cuts. Back then I was 265 pounds of muscle and bone (and some fat too), and I was fearless and foolhardy when it came to anything dealing with woodturning. There was no way I could perform a controlled accurate cut without the pin ... and man, did I ever try! The lance really had no bevel as we would know it, so nothing to help you guide the cut. The lance just had the rounded shape from the bar from which it was made. That being said, yes, some 30 years later there are probably better ways to do the same thing and better tools, BUT, Ed was a pioneer and made everything he could rather than purchase it. His favorite hardware store/turning outfitter was a local salvage yard. His faceplates were latge toothed gears. He bolted them to the wood using lag screws. Nick Cook knew him better than I did (I Think) ... perhaps he will chime in.

Hope this helps shed some light on his poor technique.

Thanks Dick, interesting stuff! I think the thing that threw me was that he appeared to be using a standard bowl gouge, hence my question. So this lance tool is more like a sharpened stick/ scraper tool then?

Thanks

Richard

 

[John Tisdale]

Home Depot Face-Plate?

The following may be of interest to turners of large work - especially those that do "twice-turned works" and the more complex, multi-coat finishes.

On all my works over 17" (most are 18" to 21" diameters) I will use the Oneway 6" faceplate. The last cut (after hollowing, sanding) is diving under to achieve about a 4"-dia base. "Diving under" is the process of reducing the 6" tenon to about 4". The 12 outer screws are 1" screws with points removed - allows me to avoid 12 unsightly holes in the lower side.

Now that I have the tenon down to 4", the piece is off the lathe never to be remounted except for final base cuts on the Kelton mandrel. But before cutting the base the bulk of the finishing/filling/sanding/yada/yada is done. Only after the surface is perfect can I cut the base and then go to the final finish process.

So, how to hold the piece. Answer: after removing the 6" face-plate from the "now" 4-inch tenon, I affix a 1/2" pipe flange from Home Depot - the four holes allow 3/4" #14 screws (pre-drilled of course). Then to my poor-man's faceplate I attach a poor-man's spindle (10" nipple or whatever length works on your fixtures).

My principal fixture is the "finishing horse". This is an all 2x6 construction - looks a bit like a lathe. The nipple can be placed in the upright of the finishing horse, a hand-wheel attached, and finishing (rubbing, brushing, spraying), sanding, filling, etc. can proceed. Recently changed the horizontal head to a tilting head - allows me to tilt up or down when doing various touch-up. Should the guys doing broken-glass tumbling desire, a pulley could be used instead of a hand-wheel and the small motor attached. Or you could do a rack like Moulthrop, motorize, and slowly turn a bunch.

Maybe not on the scale of the Moulthrops, but I keep 4 to 5 pieces in process when I'm in second-stage mode (as opposed to first-stage which is roughing). The pipe-flange and nipple allows me to do the various finishing tasks without the need of expensive face-plates or the more expensive real estate of the lathe.

John

 

[john lucas]

I'm going to take lessons this summer from a Ed Lewis in Chattanooga on epoxy finishing. Ed is a master at it. He built a slow speed rotating station that will do 3 or 4 bowls at once. The slow rotation helps even out the the epoxy. He uses West System epoxy. I'll tell you more after I learn more. I think Ed started turning along the lines of Ed Moulthroup and eventually got a Nickols lathe so he could turn very large stuff. Not sure how he deals with bubbles but there aren't any signs of them in his finishes which are perfect.
I've only seen a few of the Moulthrop pieces. One did have finishing problems. Not sure if it was due to pour handling or finish not compatible with the PEG. It appeared to be dull in spots and some possible flaking. It was a very old piece.

 

[Barry Richardson]

bubbles

On the subject of bubbles, it is a common and well known practice of flat workers to sweep a surface where epoxy or bar-top has been applied to remove the bubbles. It cause the bubbles to expand and come to the surface, thus removing them. It works like a champ. I imagine this is his reason for doing it...

 

[Bill Boehme]

Hello Gerald......Does the use of heat prevent the bubbles from forming, or does heat allow the bubbles to come to the surface and expel into the atmosphere? If it is the latter, then wouldn't this be because the epoxy is more fluid......or an increase in viscosity? If the fluidity of the epoxy is increased, then wouldn't that apply to the theory of using heat to influence viscosity, in context?

I don't know the answers here......just throwing the thought out there for discussion, or for those who do know the answer, to respond.

ooc

Fluidity is nothing more than the reciprocal of viscosity, so it is just two different ways of saying the same thing. Increasing temperature lowers the viscosity of some fluids, but not all. Applying heat to epoxy can create as many or more problems than it solves. One objective of using heat might be to temporarily lower its viscosity so that it flows better. Or maybe it might be to increase the vapor pressure of solvents in solution in order to improve the clarity of the epoxy. But, on the other hand, the higher vapor pressure means more bubbles are produced and the accelerated curing caused by heating means that the viscosity will begin to increase making it more difficult for the bubbles to escape. It seems to me that a better solution would be to increase the amount of solvents so that it flows out better and has a longer cure time. There are some epoxy finishes that do exactly that.

 

[hughie]

Hello Gerald......Does the use of heat prevent the bubbles from forming, or does heat allow the bubbles to come to the surface and expel into the atmosphere? If it is the latter, then wouldn't this be because the epoxy is more fluid......or an increase in viscosity? If the fluidity of the epoxy is increased, then wouldn't that apply to the theory of using heat to influence viscosity, in context?

I don't know the answers here......just throwing the thought out there for discussion, or for those who do know the answer, to respond.

ooc

The use of heat is a standard method of removing bubbles on two pack epoxy resin, normally its applied to doors as they lying flat and this be the reason he spins the bowls. The particular epoxy is very hard wearing bu it does some issues when applying it, but you can get a finish that looks like deep glass. Its used widely here in Australia
http://www.norglass.com.au/about

https://au.answers.yahoo.com/question/index?qid=20100423224717AA9EODJ

 

[Tony Maness]

Ed Lewis

I will be taking a lesson with Ed Lewis (Chattanooga, TN) in a few weeks on epoxy finishes. I will share his teachings.

 

[Mark Hepburn]

Hello Gerald......Does the use of heat prevent the bubbles from forming, or does heat allow the bubbles to come to the surface and expel into the atmosphere? If it is the latter, then wouldn't this be because the epoxy is more fluid......or an increase in viscosity? If the fluidity of the epoxy is increased, then wouldn't that apply to the theory of using heat to influence viscosity, in context?

I don't know the answers here......just throwing the thought out there for discussion, or for those who do know the answer, to respond.

ooc

Odie, I use Enviro Tex finish a bit. It's a two part "bar top" type finish. The instructions say that the bubbles can be eliminated by gently blowing on the product as it sets. They say it is the carbon dioxide that causes the bubbles to pop. A propane torch likely produces a good bit of CO2 gas. But I'm not saying that is what they're doing it for.

 

[Joe Greiner]

Odie, I use Enviro Tex finish a bit. It's a two part "bar top" type finish. The instructions say that the bubbles can be eliminated by gently blowing on the product as it sets. They say it is the carbon dioxide that causes the bubbles to pop. A propane torch likely produces a good bit of CO2 gas. But I'm not saying that is what they're doing it for.

More likely the movement of the air. Google Bernoulli principle.

 

[Mark Hepburn]

More likely the movement of the air. Google Bernoulli principle.

Joe,

In a bit of irony I'm reading your reply sitting in a southwest aircraft en route to Houston

So you're thinking is that the air movement across the surface creates a lie pressure zone which, in turn, lifts the bubbles? Sounds like that makes sense to me. Last time I used Bernoulli was in the navy in the early 70s. Time flies...

 

[Bill Boehme]

Joe,

In a bit of irony I'm reading your reply sitting in a southwest aircraft en route to Houston

So you're thinking is that the air movement across the surface creates a lie pressure zone which, in turn, lifts the bubbles? Sounds like that makes sense to me. Last time I used Bernoulli was in the navy in the early 70s. Time flies...

Look out the window at the leading edge of the wing. If the temperature / dewpoint spread is small enough, you might see a condensation trail developing due to the low pressure over the wing.

 

[Tony Maness]

I'm going to take lessons this summer from a Ed Lewis in Chattanooga on epoxy finishing. Ed is a master at it. He built a slow speed rotating station that will do 3 or 4 bowls at once. The slow rotation helps even out the the epoxy. He uses West System epoxy. I'll tell you more after I learn more. I think Ed started turning along the lines of Ed Moulthroup and eventually got a Nickols lathe so he could turn very large stuff. Not sure how he deals with bubbles but there aren't any signs of them in his finishes which are perfect.
I've only seen a few of the Moulthrop pieces. One did have finishing problems. Not sure if it was due to pour handling or finish not compatible with the PEG. It appeared to be dull in spots and some possible flaking. It was a very old piece.

I met with Ed Lewis this weekend in Chattanooga for a lesson in epoxy coatings. Ed is a former chemist, chemistry and physics instructor. He uses his mastery of chemistry to understand the principles of various finishes. After spending time under Ed's tutelage, I have a better understanding of the preparation, application and curing of epoxy. Ed is a true teacher with a unique style. Thanks to men like Ed, others benefit and carry on techniques and traditions.