Friday, August 26, 2016

Raised Vessels

Raising


"There is only one way to Raise- The Way that Works."

Tim McCreight, Complete Metalsmith

Raising is a metalworking technique whereby sheet metal is formed over a stake or other solid object by repeated 'courses' of hammering and annealing. (I have written about annealing in earlier pieces...)

The sheet metal, held at an angle to the raising stake, is formed using the tried and true "BANG-BANG-BANG Method" by hammering just in front of the contact point where the sheet metal meets the raising stake. When done properly, this both stretches AND compresses the metal, causing deformations in the structural plain that allow for a flat sheet to become a vessel with contiguous walls. You read that right...stretches AND compresses!!  

 When executed correctly, raising allows the smith to efficiently shape the metal without thinning thus avoiding the risk of cracking, a common occurrence. (Be Warned...Beware...Knowing is Half the Battle...Go Team Venture!) In raising, the metal at the edge of the sheet is compressed and thickened as the form is gradually narrowed. This technique is an standard skill of silversmithing and is used to create seamless vessels such as vases, cups, bowls, carafes, pitchers, euers, etc.

Why?

Good question!!

Raising, when done properly, allows the crafts-person to create a seamless vessel. This makes a vessel that is stronger, inherently, and suffers from far fewer failures encountered by seamed vessels. Without seams, you lack the capacity to have seams that did not solder, or fuse, completely. Without seams, you lack spots where differences in alloys cause problems like temperature compression/expansion differences, alloys' oxidation rate differences, rivet failure (rivets...honestly...), galvanic corrosion...so many things. Lemurs may even be involved. 

This method also require far fewer resources. Far fewer different steps. No need to cut and measure separate parts to be formed as vessel walls, then attached. Keeping in mind that each place of attachment can represent its own examples of failure, and breakage. 
Expending fewer resources on a project is key, as well. A talented smith can complete a raised vessel with a sheet of metal, a form, a hammer, and a heat source. No need to add in soldering alloys, or other complex attachment point solutions. 

Now, Once a vessel is raised, there is no reason ornamentation cannot be added...and throughout history it has been. 
Such as:





And:

Not attaching extra ornamentation is an option that has allowed for the metal varieties themselves to shine through, like this Mokume Gane piece:

(NO! Go back and LOOK at that bowl! Looook at it!!)


But, details and extra flourishes can add so much, I admit. Like in these two pieces from roughly 90 CE. 






As the quote at the beginning stated: "...The Way that Works."
There are many ways to do this. I have seen dozens of different techniques. I have tried dozens, as well. The methods presented here are the methods I use. The methods with which I feel the most comfortable. If you find them somehow unworkable, I'm open to questions. 



Starting with a circle of metal sheet. (I'll assume one has taken the time to mill out a sheet from an ingot of refined ore, and then cut it into a circle...)

Using a scribe, having determined the center, you then decide upon how big the base will be, and scribe that circle. 

Form completism, scribe concentric circles 1/4 inch apart leading from your base measurement, up to the outer edge. 

The goal is to change this flat shape efficiently into a graceful risen form. Keep in mind, if you will, that the furthest material from the center has the greatest distance to travel from the original plane, and because of this, extra effort may be required to bring those furthest edges up and into line with the rest of the desired design. 

Unlike in Sinking, where the metal is stretched by hammering on the inside of the vessel's form to stretch the material thinner, Raising is worked from the OUTSIDE of the form, compressing the metal in concentric planes, while stretching the metal in the radial direction. 

Within these 1/4 inch concentric circles, starting at the center and working around each circle, then moving to the next circle outwards, and so on, once you have reached the outer edge is called a Course, or a Coursing

For this forming method, Cross-peen hammers and cross-peen mallets are your go-to tools. The cross-peen hammers' oblong face pushes the metal twice as far on the plane of the hammers' handle, drawing the metal structure out further than it pushes it to either side. The distribution of force is directionally Inequal. 






First turn:


You are going to concentrate on placing your hammer blows just past the point where you have the sheet angled to contact the Raising Stake. 


First Full Coursing:




After each Coursing, the metal will be work hardened, and need to be Annealed if you want to continue to raise the walls further.


The making of a Fluting and Raising Stake!




 Crimping or Fluting:



 Crimping or Fluting is used to quickly raise a flat sheet into a vessel. Some prefer to sink their forms first, others claim that Fluting the form radially will allow for even more quickly raising the form.

Using the Fluting stake, make radial crimps, which will ultimately make your form look like a flower...or a very rugged cupcake paper.
Yes. I just wrote that.

Smooth these flutes over your Raising Stake using a cross-peen hammer or cross-peen mallet in the standard raising method, working from the center to the edge.



Further Raised Walls:




Walls raised high, and brought in on themselves to create a graceful necked vessel. 










No comments:

Post a Comment