Casting Filler Revisited

Has anyone seen the formula for the old time casting filler? From our previous discussions I understand it was a mixture of lamp black and shellac, but what would the ratio have been? I want to do some experimenting.

I am starting to think that the Tod Engine as delivered was not painted at all but just had a coat of the filler on everything. This explains an old pic of a Tod blowing engine that appears to have a very dark semi glossy finish. If this is so that would rule out using bondo for filler.

Hi Rick:

I would just start mixing the two ingredients until you had a heavy cream consistency, hopefully free of lumps. Might also want to try LB and a quality varnish like spar varnish (or even polyurethane), although this won't be a snappy dryer like shellac. The pattern suppply houses like Kindt Collins used to sell dry colors. The black looks suspiciously like LB in the 35 year old can I have.

John

Actually, it should be equal parts of red and white lead mixed with glycerine.

I am quoting- not suggesting

Norman

Norman:

The filler in question is very dark gray to black.

John

There is a fellow, I believe in Long Island, that sells a remix of 'Japanning', the heavy black enamel that was used on the old Stanley woodworking planes. I spoke to him once about it, but he wouldn't tell me his formula. But I have got to believe that it was similar to whatever was used on as a base on these old machines. (only maybe more glossy) If you want, I will dig out his name for you. Maybe he knows something about the 'old ways'.

I am stripping an old Hendey right now, and the this black base filler coat is tough stuff. Chemical stripper barely melts it on the smaller parts I've tried it on. I am wire brushing some pieces, and sandblasting the larger pieces. I am using Bondo and glazing putty, then priming, then spraying with RustoLeum 'hammered' enamel. So far so good. I thank all those who have contributed to these threads that discuss how the ancients did things.

I've seen old machine tool castings that were filled with a plaster-like material where significant areas and filler volumes were involved. I don't know if the stuff was acually plaster but it certainly had that consistancy and the masonry odor. The stuff I've had experience with was very strong but brittle. The pick of a welder's hammer broke out little conical craters about the size of a coin and the underlying material was dirty white.

Good plasters are very efficient at applying smooth coats of their stuff even to curveds surfaces. I would imaging the arts of the plaster and the bodyman would overlap in this application.

If I was going to fill and paint the castings of an old machine, I'd first look for a good bodyman. Good plasters are scarce these days. As for filler, the two part cream fillers and high build spray-on primers are sure hard to beat for strength and convenience but if you're filling the castings for a large machine tool the materials can get real pricey.

Red lead and white lead with glycerine is an excellent high pressure lubricant for assembling rail wheels on their axles but it will not harden. You may be thinging of litharge and glycerine. Litharge is lead pentoxide. When freshly mixed with glycerine it will react over hours to become a hard, slightly expansive material perfect for permanently assembled valve componenets like false seats in hot water and stean service. This stuff is quite expensive and unsuited for think applications. Besides when it sets is a significant volume it's exothermic progressive and may cause a fire.

Look in Van Nostrand's "Formulary." There are many recipes for cementacuous products some of which are appplicable as machine casting filler.

Forrest Addy! You are quite correct- it was litharge and not white lead.

Somehow, I think that I got too near the white lead! If you know what I mean.

Norman

Rick, I suspect you need lots of filler what ever you use. One consideration is that it lasts, so you don't have to do all the labor twice....or more. That may warrent more modern materials over the traditional stuff.

dan k

Source for 25 LB bags of Lamp Black

http://www.mannbrothers.com/products/colorants/drycolors.htm

John

As an after thought, polyester resins also exotherm. Another thought is that many added fillers render the job porous. You can't or shouldn't, rub down with water.

Having worked in the plastics industry, I made my own filler for one of my lathes. In a word, No!

Norman

As an intermittant boatbuilder, I've made surfacing (or in boat lingo, "fairing") putty by adding microballoons, and sometimes a bit of silica, to resin. Although its probably an expensive option, might be useful for some special applications - try West System for more info.

Jeff

The casting filler that is on the engine now has failed in several places but still have very good adhesion on about 40% of the surfaces. Not bad for a material applied 92 years ago.

Take a look at this picture of a Tod blowing engine built about 8 years before our engine. This pic was taken when this engine was new and even though its B&W note the color and finish of the castings.



It sure looks to me like the surface is a dark grey or black with a deep metallic sheen. My theory is that they coated all the surfaces with the lampblack/shellac coating and then just shined it up really well with an oily rag.

I want to duplicate this sheen on our engine. Any ideas?

Of course lampblack and shellac was the traditional finish for wood patterns in the pattern shop. Vermilion and shellac another, etc, depending on what part of the pattern.

When I learned this in the 1970's I started mixing Germantown lampblack and shellac for use on wood products--picture frames mostly, but a fair number of other shop works.

Indeed, if the lampblack is well and uniformly mixed, without lumps, the black coating has a soft sheen, on wood or metal, is a 'silky' black. (Silky referring to the cloth when the cloth reflects and absorbs light in a distinctive way the paint covering seems to imitate.) Shellac, of course has good adhering properties also.

I have an old can of litharge which i think came from the iron works also.

It goes without saying that somethign as big as that engine ought to be doen right the first time.

Northernsinger

I have trouble thinking of doing somethign that size with any but modern materials....

-But-

If you do decide to mess with shellac and lampblack, don't mess with the premix shellac. It will never set as hard as what you mix yourself, and if it is old, it may never set hard at all. It also will not set fast enough to work with the way you would want for efficiency. Good shellac is pretty expensive these days, but I think it would be a mistake to scrimp. Also, cheap premix won't give you a good feel for what it should behave like.

I don't know if the old guys used de-waxed shellac or not, it is worth investigating. If you buy premix, pour it in a glass jar, and let it settle overnight, the bottom 1/3 of heavy white gloppy appearance is wax. For furniture use it is "bad" as it leaves the finish porous compared to de-waxing. Flake shellac is generally sold de-waxed, so that is another plus for mixing your own. (All the wax from de-waxing shellac used to be the base for shoe polish. I don't know if the industry is still big enough to support that use or if synthetics/petrobase wax has taken over....then again, routine shoe polishing isn't what it once was either )

A few years ago I used to get de-waxed superblonde flake shellac 7 or 10 lbs at a time from a guy who sold the best stuff imported into the US as a sideline for about $10/lb. He decided the sideline took too much time and disolved the business.

Here's a current dealer, but I have not yet needed to replenish stock and have never ordered from them.

http://www.shellac.net/ShellacPricing.html

It takes about 3lbs/gallon for a "thick" mix, (or about 1-1/2 to 2 lbs/gallon for a mix used to french polish furniture.)

smt

I am going to experiment on a small area with the shellac mixture and then decide if its worth fooling with on the entire engine.

Steve, thanks for thelink but there are 13 varieties of shellac. Which should I order? We are getting into areas that I have absolutely no knowlege of when talking about shellac and wood finishes.

I did notice that the website states that the shellac is not waterproof. That is at odds with the material on the engine which has been in the rain for a year and even after hot water pressure washing will not come off.

BTW what exactly is shellac made from? The website talks about trees and bugs and such.

Yes, the story of how shellac is produced is pretty astonishing. Somewhere, I have the story, on a CD, I think on a collection I was given called Robert Crumb's sweet Shellac. Crumb has a huge collection of old 78s' (presumably they were made from shellac). Included on the CD is a description of the err.. process. It does involve insects ("an infinite number" and trees.

Hopefully someone can find a web-based description to save me having to listen and type...

When I was growing up, the only gasket cement we seemed to use was shellac, came in little bottles with a brush built in to the cap. Nice smell if I remember correctly.

Just found/listened to the story on the CD, it was an essay written by Primo Levi. Will try an find it later on the web.

Apparently shellac is amazingly stable, over thousands of years (is that long enough Rick!?), they have found shellac-coated objects in Egyptian tombs, still in good order.

So those old records will be still going strong when the digital things have disapeared into the ether..

Rick:

I may be all wet, but here goes. My dad used to say Shelac was made from the "lac" bug , but I cannot be sure if he said this tongue-in-cheek or not.

I gather the little critters are mashed up to provide some natural "plastiser". I suppose a by product of this is the wax mentioned above.

It it mixed with alcohol which tends to dissolve this mess into something useful.

Actually, the dictionary says "lac" is a resinous substance secreted by a scale insect - so maybe the "bugs" themselves are not actually an ingredient.

John

I believe chinese lacquer is shellac, both made from the Lac bug. the Chinese built up lac ware, wood shells with hundreds of layers of lacquer on them that came out like melamide plastic. Anyways Rick, look into a japaned finish, or japan black. I believe it was a linseed oil paint with alot of dryer in it [lead?] that was a subsitute for black lacquer. From 25 years ago I remember getting specs from American Optical , Cambridge Medical and Bausch and Lomb changed from japaned to powder coating, because the japaning was not available anymore for what ever reason. B+L also had negrozine speced on things, which after much reasearch was simply an old fashioned black stain. I seem to recall the finish on steel banding used to be called japaning, but who knows how loosly that was used. The point is look into a linseed oil- lamp black finish or possibly bone black. Bone black [chared bones] is some what transparent which is what I think you need to get a deep sheen you are talking about. Think of a powder coating, which is thick and fully opaque, it has no depth, because it is opaque. A local small paint manufacturer could probably help you with this and mix what you need. In the mid 70s I worked for a old timey house painter in Cincinnati who had all the old skills, like graining, marbelizing, etc, and he went to a old paint factory and got even a couple of gallons mixed up special. Like Lindseed-white lead for canvas porch roofs, etc. BTW, the old time bone black that artists used was supposed to be from human bones from India, which was quite possible. Just like India Yellow was made from the urine from cows who only ate mango leaves, which produced a deep billiant yellow that is stable, but probably incredibly expensive.

chinese lacquerware is made from a plant secretion and is not related to lacquer from the lac bug. The chinese stuff (for some reason someting like "muroshin"(sp?) comes to mind) is a somwhat poisonous resin like sumac. It is cured by moisture (like polyurethane!) by storing the ware in a hot humid environment between coatings.

smt