Hot Stuff

It has been a few weeks since my last entry with the Easter holidays, a trip to São Paulo, house building and most importantly last week end´s Ox Tail soup, with chocolate, cinnamon and star anise.... Delish!!!!!
The trip to São Paulo was twofold, to buy gemstones, some tools and consumables for jewelry making; as well as to visit friends and family. We also took the opportunity to show my work to a number of people and it was I am pleased to say, well received.
http://www.pinterest.com/essexvig/my-work/

I am almost at an end to the silver sheet that I had bought in London and Buenos Aires previously, so the time had arrived to start doing something seriously about producing my own material, as I have mentioned before you can´t buy sheet silver in Brasil.
Having researched what should be done I felt fairly confident that things should turn out OK. Looking at what I have ended up with after a few hours work I am quite happy with the results.
My first step was to season my melting dishes, one of the things I bought in São Paulo was a kilo of borax, which I noticed was from Argentina, which reminded me of a trip a few years ago to Gran Salinas an area of salt lakes near the border with Bolivia.

Despite it being winter the sun shines brightly and the local artisans who make and sell souvenirs carved from salt make sure they cover up well to shield themselves from the UV glare.

What has this to do with casting silver you ask, not a lot except we stopped at a local homestead for a meal and the owner worked previously in a mine locally that produced....Borax. He unfortunately had an accident in the mine and could no longer do the heavy work. 

It is a long way from anywhere, something to ponder when you use borax next.

I managed the seasoning of the melting dishes (I bought small medium and large as they were relatively cheap) without mishap except one dish had way too much borax but this was easily fixed by pouring off the excess. I allowed them to cool before use and the coating was a nice even clear glassy layer. 

So on to the casting, I found this video a few days ago and despite it being in French I picked up a few useful pointers. 

http://www.youtube.com/watch?=Bt6iyNsJdPA&list=PLO7Qs9JKDBsXEH7KlqoAnNM7TTmb6-xjL

The ingot mold was lightly oiled which stops the silver fusing onto it, then positioned at the back of the melting dish to preheat it. The only problems I had with the new ingot mold were with the clamp that fixes the two halves together, firstly it was painted, and secondly the knob on the clamping screw was plastic. So yes we had the sweet smell of burning paint and a plastic knob that squished when I went to release the clamp. No dramas however, the paint is almost all burnt off and I will drill a cross hole in the clamp screw for a tommy bar.

This is the model torch I have, it is a fairly large torch and runs off bottled gas, it proved more than sufficient to heat the silver in a reasonable time and provide enough heat to preheat the ingot mold which is quite large. 

This is the style clamp I have for manipulating the melting dish, it holds a range of sizes and clamps them very securely. 

Once the silver began to show signs of becoming hot, small amounts of borax were sprinkled over it. This does two things, firstly it acts as a flux and protects the silver from oxidising and secondly  it cleans up the metal, it turns a dark brown colour , this I understand to be the copper oxides in the silver.  

The first small batch was my bench scraps, this produced the smallest ingot of 13 grams, the problem here was lack of heat in the silver and not having the torch directed onto the silver whilst pouring. 

The second attempt, the mid sized ingot of 24 grams again did not fully fill the mold, I tried the larger mold as I thought the length/width ratio was too great in the first attempt. 

The largest ingot of 69 grams, my third and final attempt was reasonably successful, the main fault I can see is that I have been a little over generous with the borax and I have some inclusions from this. I don´t believe this will be a drama as they are on the outer edges, and a spell in the pickle pot should remove them.

I believe this cast was better for a number of reasons, however there are still signs that the silver was starting to chill looking at the edges of the ingot. 

I am fairly certain that for the first two casts the silver was not hot enough and not all the silver was completely molten, I thought of melting chocolate or ice cubes in a drink was a close analogy.  

So whilst there was molten silver there was also chunks that were not, and these would cause a blockage and prevent the silver from filling the mold. 

The melting point of silver is around 960 deg C. So if my silver was at this temperature the silver would be molten, but would have insufficient heat to lessen the chilling effect when the material enters the mold. So whilst the mold has been preheated it will still absorb heat from the silver resulting in it becoming solid or pasty. I have since read 1050 deg C is a good temperature to aim for, this ensures that the silver is all molten and you have sufficient heat in the molten silver for the chilling effect of the mold to be diminished. I don´t have any means of accurately judging the temperature of the melt but I used my stainless steel solder pick to check to see if there were any portions of the silver still in the solid state and once satisfied I held the heat on for a short period. 

For the first two pours I neglected to continue heating the silver whilst pouring, so I believe these factors contributed to the final successful ingot. 

The largest ingot measures 16 x 4 x 100 mm

My rolling mill does not have reduction and I am not to fussed about rolling everything down to thickness. I have seen on a few videos from Japan that after casting their ingot they forge the ingot to a size close finished size, then finish in the rolling mill. Whilst swinging a hammer is is not exactly my idea of fun, I think it is preferable to hours of rolling metal to size.

Needle File Storage

I have managed to accumulate quite a number of needle and rifler files over the years and these were stored in a range of tins and plastic boxes. This was not the best way to do things and could be quite annoying to rummage about trying to find that particular favorite file. So a better solution was sort. This is the design I came up with and it has worked well for me over the last 10 years or so, hopefully it will be of some assistance to you.

The base is a sheet of 8mm PVC about the size of an A4 sheet and the tubes are 32mm diameter PVC waste pipe. The advantage of using PVC is that it is easily fabricated into a range of designs using the cement that is supplied for fixing PVC pipes and fittings.

My piercing saw blades are in a jumble and a project for the future is to make up something similar using 12mm diameter pipe. 

I hope this gives you a few ideas for solving your storage problems.

Some Woodspoiling

I have recently just bought a small rolling mill, the main reason for the purchase is that silver sheet and wire are not available here in Brasil, or if they are I have yet to find a seller. Along with the rolling mill I also have bought an ingot mould and some silver grain, my attempts at casting an ingot will have to wait a week or so as I have to go interstate.

This ingot mould produces round ingots or rectangular by reversing the plates

Having bought the rolling mill the next question was where is it going. The model I bought does not have reduction gears, so a fair amount of torque is required to get the material to pass through. For an initial try out, I clamped the mill to my existing bench with a G clamp; over optimistic in the extreme. The bench is fine for light jewelry work but just not up to the duties involved in rolling metal, additionally it was too low. 

As the rolling mill will be in regular use and not a seldom used luxury, something serious was called for. Firstly I determined the height the mills needs to be so that I am standing erect (not a Neanderthal look alike) when the handle is at its lowest point. 

The completed bench ready for action

I decided to use hardwood throughout for strength and weight, the legs are 80x80x950mm, the top is 2 pieces of 30x300x1300mm both angelim (similar to teak).  The top rails are 50x100mm and the lowerails are 20x80mm both eucalypt (probably Blue Gum).

The rails are morticed and tennoned  to the legs, I made the mortices by rough chain drilling then chopping out with a chisel and finishing with a rasp. The tennons I used my circular saw to chop out and gave a final finish with a rasp to take off any rough spots. The joints were glued using PVA glue and pinned with two 8 mm wooden dowels for each joint.

The top is screwed to the base with ten 75x6mm csk wood screws and is quite secure and the mill is bolted down with four 8x75mm hex bolts.

So I am now ready for action, or perhaps a hernia, if the preliminaries are an indication of what is to come.

I will hopefully be able to show you some successful results soon.

A Brasilian Anyone

I have been trying my hand at repousse as this is an area that I find of interest but my initial results using black pitch were not exactly encouraging. The pitch worked fine as far as producing the formed item, BUT it took ages to prepare the pitch (much heating and black smoke) and when annealing the sheet the fumes from the pitch remaining on the work were not exactly healthy.

  

I looked around for alternatives and initially tried candle wax stiffened with talc (lower melting point and less fumes), this worked to a degree but was on the soft side and lacked the stickiness to hold the sheet.  
   
In Brasil where I am now living I came by chance  upon the ideal medium , namely depilation wax. The wax consists of beeswax and resin (which I believe is shellac), which is fairly much the same as one I found a French site. It melts easily and quickly, less than 100degC and the vapours when annealing are easier to get along with than the black pitch. I use a hair dryer to heat the wax and sheet and this only takes a few minutes. The wax initially was on the brittle side, an addition of small amount of olive oil gave me just the right hardness. 

This is the latest ring that I have designed using this wax.

http://www.pinterest.com/pin/546413367261943736/

Before committing a design to silver I make a trial of the design using sheet from aluminium cans, these are some ideas I am considering.

The pitch bowl I use is a small stainless steel cereal bowl, and this sits on a small sand bag. The punches are ones I have made myself using budget price center punches from discount tool stores. The punches were initially rough ground using a small bench grinder, final shaping being done with a small hand held rotary tool and diamond files. For final finishing oil stones and wet n dry paper gave an acceptable result. 
  
I have yet to discover if silver steel (drill rod in USA) is available here in Brasil or a stockist of any suitable steels with a carbon content around 0.7% -1.0% for making further punches, I just have to persevere and improve my Portuguese. I will post details on my punch making efforts at a later date.

The beauty treatment.