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More Improvements to Gelatin Molds For Plaster Casting II

Armed with the knowledge and experience of recent attempts at making gelatin molds for plaster castings I charged forward with some new modifications to the formulation of the gelatin.

In this iteration I used the following recipe:

1 part 135 gws glue (dry granules)

1 part water, soaked overnight and cooked twice

3% glycerin

3% gelatin hardener

0.5% borate preservative

*Note: it is important to actually record the weight of the dry glue granules as the other additives are based on that number.*

Once the glue was well-cooked I added 3% glycerin and 35 of the hardener.  These numbers were based on the dry weight of the granules, in other words for 200 grams of glue granules I added ex poste 6 grams of glycerin and 6 grams of hardener.  I then added 1 gram (0.5%) of borate complex powder as a fungicide to extend the lifespan of the mold itself (not borax from the hardware store).

The working properties of the gelatin mold were excellent, although the time required for it to lose the requisite moisture  to become robust enough to use as a mold took longer than I expected.  I waiting a day before demolding from the pattern, two days would have been better.  But the resulting mold was extremely tough and utilitarian.

I cast plaster into the mold and demolded that the following day. Like the original demolding, longer would have been better.  Next time I will try 36 hours rather than~20.

The plaster casting was still pretty green since it took so long to slough off the water, so I placed it into a desiccation chamber to draw out the water.

The mold itself was placed into a sealed kitchen container with a damp sponge to maintain the water content of the mold, and thus its viability as a flexible and functioning plaster mold.

After three weeks I checked the mold and found a little bit of surface mold.  This was a useful observation.  The initial mold from many moons ago was a lump of goo after two weeks, this was still sort of viable after three.  I think next time I will jump the borate salt content to 0.75% or even 1.0% to see the result.

All in all I was very pleased with the progress being made, both conceptually and practically.

Stay tuned.

Veneer Repair Video Episode 4


Our series continues with an episode focusing on the tools needed and the set-up for making visually harmonious veneer repairs to losses.




If your conscience is pricked feel free to click on the “Donate” button, any proceeds from which will go toward enhancing the rapidity of new video production.

Future videos will also be available for purchase one section at a time (perhaps $0.99 – $1.99 per segment depending on the video) or $15(?) for the complete product.  I am still noodling that and working out the logistics with Webmaster Tim.  If this interests a large enough audience I hope to produce three or four 2-hour-ish videos per year.  If not, maybe one or two at the most, one being more likely.  In which case it will take me almost twenty years to get through the list I have already.




Where Did I Put That Stinking Knife Handle?

Recently I was sitting down ready to incise the pattern into the block that would become the pattern for the mold for making my soon-to-be-available Blend 31 block wax.  It was at that moment that I realized I had put the handles for my detail knives someplace for some reason I could not remember.  It was not that I had misplaced one of my handles, I could not find any of them, suggesting I had collected them for some purpose that I could no recall.  Fortunately they will be found as soon as my task is completed.

In the mean time, I needed a handle for the knife blades I needed to use.  So I made one.

Taking a piece of dowel stock from inventory I sawed a small slot with a fine Japanese back saw, inserted the blade into that and bound it with twisted copper wire, much in the same manner as quill brushes.  It worked just fine for the carving of the mat board that was the detailed surface of the block pattern.

An hour later I had the design incised into the surface and the block was ready for making the rubber mold.

 

And sure enough, the box with my micro tools was found right after this was finished.  Sigh.

Workbench Wednesday – #12 (2015) Studley Replica Top Completion and Exhibit

With the laminated slab top assembled the task at hand was to get the Studley bench pastiche ready for the May 2015 exhibit. The purpose of this bench was to show the to the exhibit visitors the construction method Studley used for the top (the top was the only remaining structure remaining from the original work bench) and to hang several vises analogous to those of Studley’s.

I fabricated a pair of torsion-box end “legs,” joined to the underside by a pair of box cleats, and fitted together with a stretcher adequate to the task of it serving as the exhibit element.  I smoothed the top with planes and scrapers, and varnished it nicely for the exhibit; once back home that would be undone as it was a surface unsuited for real work.  With the edge trim affixed to two sides to better elucidate the structure, it was ready to hit the road.

It served its role well in Cedar Rapids.  Now it was time to get it back home and put it to work.

 

More Improvements to Gelatin Molds For Plaster Casting I

Last month I brought together all the new information I had derived from the initial gelatin molds exercises to see if I could nail it on a more complex application.  For this project I used a pattern derived from a cast pot-metal satyr’s head mount from a 19th century pastiche of a 17th century French desk.  The hardware on the desk was cheezy and poorly finished (I was only interested in the desk itself as it was the earliest intact example of “mastic tortoiseshell”; another tale for another time).  This was probably a poor choice for a pattern because its level of “finishing” made it difficult to ascertain the ultimate success of the new mold and casting.

Just before this endeavor I was doing some winterizing and had a bolt-of-lightening stroke of inspiration.  As I was affixing the shroud around the window air conditioner with rope caulk I suddenly noticed the similarity of the rope caulk to the gaskets I made from modeling clay for my molding and casting.  Could it work the same way, but without the time involved in making the the initial gaskets?

I could hardly wait to get back home to try it out.

Fabulous!

I built the form-fitted Lego casting dam for the pattern/mold and quickly laid in a bead  of the rope caulk as the gasket on the inner edge of the underside, and pressed the assembly together.  The adhesion and squeeze-out was basically perfect.  Rope caulk is formulated to stick just enough to make it through the winter and then be peeled off with no residue in the spring.  Cleaning off the squeeze-out required only a pass with a boxwood sculpting tool configured  with a knife edge.

Suddenly I was in possession of a new technique to cut many minutes out of my pattern/casting dam set-up for the remainder of my working life.

It was now time to move forward with the modifications to the gelatin formulation and make the mold.

 

Up A Creek Without A Polissoir

At the recent gathering of the Professional Refinisher’s Group one of the presenters was addressing a topic that would have fit seamlessly with the use of polissoirs.  When I asked the host for his, I was informed it could not be found.  I canvassed the group and none was to be found.  Even I had not brought one with me!  While I normally travel with my rolling Store for some reason this time I did not.

But with a little thrashing around and some yeoman’s help from TomD we made one that worked enough or the task.

The starting point was the old shop broom, a roll of twine, and my dull Victorinox multi-tool knife (dull because I had cut some wire and had not sharpened it.  My bad.)

After cutting of some broom fibers we set about trying to find the string necessary.  We could not find anything really robust, what we found was some soft twine similar to macrame yarn.  So we used what we could find.  (I think the broom went back to hang on its nail, ready to go to work albeit a little less effectively).

Working carefully, and celebrating the fact that my broken arm from two years ago has recovered almost all of its dexterity and strength, I started putting it together.  My biggest challenge was trying to work right up to the limit of the tensile strength of our soft twine.  Normally I use heavyweight waxed linen cord, which I literally cannot break by hand, resulting in a polissoir so tight it has a sharp sound when rapped against a hard surface.  This undertaking did not yield such a result, but the polissoir was tight enough to serve well enough for the task at hand.

I trimmed one end  and we put it to work.

I’ll know to never travel anywhere without a polissoir in the future.  Note to self: when packing for a trip, it’s glaucoma meds, toothbrush, and a polissoir.

Test Driving A Prototype

For the past several months I have been cheering on Steve Voigt in his quest to make brand new toothing planes in the style of his vintage-design plane line-up.  A while ago he was speaking at the Washington Woodworker’s Guild and I brought a half dozen of my vintage toothers for him to examine and measure.

A couple weeks ago his first prototype arrive at the barn for me to test drive.

It is a lovely artifact as you would fully expect from Steve (or any of the other of our contemporary planemakers — none of them are making anything less than superb tools) and I delighted in getting it set up.  It was a feast for the senses, beautiful visually in its proportions and craftsmanship, fitting my hands like and old, well-worn glove.

I know Steve is working on a plan to make his own irons but this one was a vintage one in remarkable condition.

Steve is definitely on the right track.  I made a lot of the teeny toother shavings and found that it leaves the surface well-prepared for whatever you want to come next.  I made notes on my observations and sent them back to Steve, and will return the tool itself for a couple of very minor modifications to transform it from merely excellent to exquisite.  I cannot wait to get it back as a purchase, it will likely become my most heavily used preparation plane.

All A-buzz

Many times in the studio I need to shake something, just a teeny bit.

For example, when casting plaster or plaster like materials, such as ceramic media for lost-wax casting investment, it is sometimes necessary to tap on the mold container to dislodge air bubbles that all too often get lodged against the surface.  If they remain there the casting will be diminished, even ruined.  Many years ago I looked into getting a vibration table for buzzing the molds while the medium was still liquid, loosening the bubbles to rise to the surface.  After pricing the available devices I decided to go another route.

What could I use to cut the cost of a vibrating table down to near-zero?

Hearkening back 55 years to my times with Stan the Barber I recalled two things — Stan always had the latest comic books for the boys to read, a real treat for me because we were too poor to get them, and the tickle of the vibrating electric clippers on my neck when he was trimming up.  Could electric hair clippers be part of the answer?

The next time I ran across some clippers at the thrift store I decided to roll the dice with a buck-and-a-half for the clipper.  I combined the tool with some scraps of wood, two pieces of plumbing strap and a few screws.

Viola’.  A vibrating table for a couple bucks and a couple minutes.

Workbench Wednesday – #12 (2015) Studley Replica (Top) Construction

The main point of this bench was to replicate Studley’s construction of the top for display at the 2015 exhibit of the HO Studley collection in Cedar Rapids, concurrent with the 2015 Handworks event in nearby Amana IA.  I had to guess at the details of the actual construction of the top since the owner of the Studley collection would not allow me to take a large core sample or cut a chunk out of the original workbench top.

 

Being limited to the observations I noted last week I charged ahead  The white oak I’d purchased from Jameel’s supplier was about the hardest stuff I have ever worked, it was rosewood hard.  After coaxing it through my lunchbox planer I assembled the two core  lamina using PVA glue and decking screws with washers.  Assembling laminate structures in this manner was a technique from four decades ago during my time in the foundry pattern shop where we glued and screwed or nailed everything together so we didn’t have to use clamps.  When it came time to sculpt the pattern for the molders on the foundry  floor we went back and removed all the metal fasteners first.

I repeated the procedure for the underside face of the bench.  C’mon, it was the underside.  Who cares if there were dozens of screw holes?  I know I certainly did not.

The show face consumed pretty much every clamp I owned in order to avoid the screw holes.  In the end I had a terrific flat and stable slab, just like Ol’ Henry did.  He was right about that, too.

The Every-Other-Morning Winter Ritual

My morning routine over the winter involves a light bit of attention to the wood/coal stove one morning and a more in-depth regimen the second day.  Here is how my day usually begins for the heavy heating season from about the beginning of December through mid-March.  I guess I could just rely on the propane wall furnace, but since propane is the very highest expense method I am disinclined to go that route.  I’m guessing that would be somewhere north of $750/month even though my workshop is super-insulated (R43 XPS panels).  I longingly note the falling prices of gasoline and the simultaneous rise of propane prices, the last fill-up was almost $4/gallon.  So instead I rely on my triple combination of wood, coal, and kerosene.

On half of the mornings I arrive to a half-clean firebox with a few glowing coals, keeping the space between 45-40 degrees requiring only a couple minutes of cleaning out some of the clinkers.  All I have to do is fire it up again and it is ready to work all day and through the night.

On that second day, however, the residual pile of clinkers requires a pretty thorough cleaning of the firebox.  I must say I am pretty disappointed at the mound of clinkers remaining after the fire, I’ve been buying what I thought was good quality anthracite but as you will see there is always a full bucket of clinkers to get rid of.  If I had cleaner burning coal my clean out would take two minutes a day.

 

This is what the fire box looks like after two days of burning.  The clinkers fill the bottom from the bottom horizontal grate, slightly below the bottom of the opening, up to the top of the removable fence grates in the front.

The front fence grates slide up and out, giving me full access to the bottom grate so I can shovel out the clinkers.  (The ash falls down into the ash box below.)

It is now time to lay the foundation for the new fire to come.  I put the bottom fence grate in place and fill the space behind it with coal to a depth of 2-3 inches.

It is now time to turn my attention to the ash box, which slides out like a drawer.  Its contents join the clinkers in the ash bucket.

Unfortunately the ash box goes into a space that is larger than it is, so the areas outside the ash box need to be cleaned out too.

Once everything is cleaned out and swept the whole assembly goes back together.

On top of the bed of coal I place a paper towel left over from its use as a wax filter, then pile kindling on top of that.  I leave a little tail of the firestarter poling through the front fence to give me an easy place to light the fire.  Which I do.

Before long I have crackling flames.  This usually takes a minute or so.

After about three minutes I set the stove doors for maximum bast furnace effect.

About 5-7 minutes later the chimney is hot as a pistol.  This is not the heat level I maintain, I normally operate the stove near the bottom of the operating range.  I can now leave the stove on its own for an hour or so, then add another piece or two of firewood and another couple scoops of coal.

Meanwhile, upstairs at the floor level of the shop, I  have created a heat stack vent by raising the chimney collar.  This allows the hot air from both the stove and the chimney to more easily enter the shop.

Usually about the time I get back upstairs the stack is providing hot air for the space.

I augment this with a small fan blowing on the chimney to distribute even more heat into the space.  I used to have a heat exchanger in-line in the chimney but have it currently removed because it requires constant power and in the winter I often power down my entire system at the end of the day.

I add additional scoops of coal a couple times throughout the day, but mostly I just get on with my day, loading it one final time when I close up for the evening.

I cannot pretend I am completely satisfied with this system.  We are looking into upgrading the heat source for the cabin, and I just might do so for the barn too.  I’m thinking about a Kimberly gasifier stove but am still gathering information.