"Metal for casting - complies with what standard ?" Topic

I am currently offered two standards of lead free pewter, both without bismuth.

The cost difference in bulk is still quite significant, and both suppliers claim it meets or exceeds the international standard on which BS (long number I have not got in front of me) (1997)

for the purposes of the Kickstarter – should I order a sample of both metal and send it for independent testing? or should the certificate I get from the providing company indemnify me for their failure if it fails to meet the specification it is supposed to pass?

I have priced my kickstarter using the most expensive of the two suppliers (?) and assumed a certain weight needed – but further bulk of order will reduce costs further per kilo (should I take this as a bit of profit if I get that far… or should I throw in an extra duplicate figure as a gift)

should I take this as a bit of profit if I get that far… or should I throw in an extra duplicate figure as a gift

I think I can predict what the consensus will be on that question….

If they claim it meets or exceeds the British standard, and it fails to do so, I would have thought you have a pretty good claim against them under S.13 and S.15 of the Sale of Goods Act:

The Sale of Goods Act 1979 (SGA) provides four main protections for buyers:

1. The seller must have the right to sell the goods ( S.12)
2. Goods sold by description must correspond to the description (S.13)
3. Goods must be of satisfactory quality (s.14)
4. Goods sold by sample, the goods must correspond to the sample in quality (s.15)

I've a background in museum research and have done plenty of work with various big musums like the V&A and the museum of british pewter looking at the evolution of low melt casting alloys over the last few hundred years, work which has included both analytical studies of old pieces and experimental work casting with a whole variety of blends of alloys. I'm also involved in the model making business casting a wide variety of small parts such as gaming miniatures. As such you could say it's an area that I know a little about.

The first thing I'd say is that large reputable companies, ie those with a reputation to lose through bad publicity will supply alloy made to the standards they claim, testing it really isn't necessary and to do it reliably won't be cheap. The companies to be wary of are those that won't/can't give you a detailed analysis of the composition of the alloys they sell; they are the ones that recycle all sorts of bought in rubbish and simply melt it down with out ever refining it or identifying what's in it or what it's going to be suitable for. Consequently their labels mean nothing and you'll get inconsistent results as each ingot may behave differently to the next.

Don't however assume that exceeding any partiuclar British standard makes it suitable for what you want. The ones that give the best results for you may be the ones that fail to meet any of those standards. You need to choose alloys that suit the type of casting equipment you are using and the shape, size and level of detail on the parts you are casting as you need to balance out things like flow, flashing, cooling, shrinkage etc. Using a metal that's "safe" to make tankards out of doesn't offer any guarantee of suitablity for casting miniatures. This brings me back to my above point, you need to be able to tell the metal merchant what type of alloy you need for a partiuclar project, rather than accept what they sell. If all alloys behaved the same there would be no need to supply lots of different ones, every supplier would simply sell the one they could manufacture most cheaply; as with most things in life you get what you pay for, and to get best value you need to know what it is you want and need so you can assess if the price seems fair for your purposes.

The art/science of casting and blending alloys is a fascinating subject, one which few miniaturists know (or need to know) much about. Still if you are buying metal I assume that's because you intend doing your own casting (rather than contract it out)and therefore have some prior experience. If you are taking other peoples money on a Kickstarter, and intend casting with no prior understanding of this thinking it will be quite straightforward… Well…. errrmmmm!

As for Bismuth, it may have health implications, which in turn can affect what sort of health standards alloys including it will meet, but there's a reason several model makers still prefer an alloy with a touch of Bismuth in.

In terms of metal supply, I disagree with Aidan on metal suppliers and getting what you pay for when it comes to pewter or any metal. They have a variety of customers with a variety of needs.

Before questioning the standard as put forth to by the metal suppliers, you need to find out what the differences there are in pewter, for there are different levels of pewter based on what it is to be used for, and thus the various price differences.

Your reaction to the salesman from the metal company tells more about you that the metal company. It tells me that you are new to what your are doing and therefore can not give the metal supplier the exact information that he needs to sell you the exact product that you need.

Now, I do say this from experience, as I was looking into doing high density foam casting. I called a company that supplied the products, from equipment to foam. I didn't get anywhere with the salesman because he had too many products and I not enough knowledge about what I needed. And based on our conversation, he came to the conclusion that I had no idea of what I needed or what I was doing that therefore was wasting his time. He told me to call back when I had a better idea of what type of equipment and foam I would need.

The same could be happening to you. You want to get into manufacturing metal miniatures, you call a metal supplier, but he is not sure what you need and therefore to cover all his bases, he gives a list of pewter products and now you have to make up your mind as what you want to do.

How can one "exceed" standards?
"A little more tin than is called for!"?
The standards would be a simple declaration of the percentages of each metal, wouldn't they? Does the standard include a +/- allowance?

considering that each of the metals in the alloy have a different function, how can one "exceed" the standard?

To reiterate what Joel says, I was the "Technical Services Manager" at our company years ago. I would interview the adhesives salesmen, show him the substrates (typically ABS and supported vinyl), give him the manufacturers' specs, projected volume, budget for dispensers, etc.
You have to know what you know, and what you don't know.

I have not chatted with either company, I have sent off the spec, and both companies have quoted based on a 25kg purchase of alloy that contains no bismuth, no lead

The percentage of tin and copper vary very slightly, and one has a point one per cent more of antimony in it.

I have used both metals before, and a cheaper grade from one of the companies that contained bismuth in small quantities that was ok, flowing easier and holding detail well.

All three metals work, both suppliers are big companies and obviously if I need twice as much metal the price reduces again.

I can arrange independent testing, to verify the content, but it is expensive and I would be happy to skip that, since other UK companies use the same metal supplies.

(I am getting a new melting pot since the current one is old, and not as energy efficient as I would like)

Thanks to everyone for their advice. It's an s 98 lead free pewter that complies with the insi standard published in 1997.

I can arrange independent testing, to verify the content,

Aren't they self-certified, with ISO-9000 and all that?
Why should you pay for it? That's what ISO is for!

Miniature ships, I am not sure what part of my reply you disgaree with as it seems you have basically reiterated what I said.

The point I was making is that different alloys are mixed to achieve different things. You need to know what sort of alloy will meet your needs so you can pay for the right thing rather than just buy what somebody tries to sell to you. If you don't have the experience to judge this for yourself then you need to trust the sales staff to understand their subject and offer good recommendations based upon you giving them a description of what you are trying to cast, rather than have them sell to you what they make the most profit on.

So then, what is the percentage of the other metals involved?
It may be the cause of price difference, as well as the amount of Tin involved.

Pewter used to be defined as any high tin alloy, now legally that must be at least 90% tin, copper and antimony are the two most common alloying elements, but bismuth, lead and silver are often deliberate additions to modify properties. Many more elements occurs at trace levels depending upon the source of the ore and certain mnaufacturers favour other deliberate additions perculiar to themselves.

Most model casters will buy in one or two set blends of known composition from a favoured metal merchant and use these for most projects, though it can be useful to keep small amounts of the pure metals to hand to modify an alloy mix for those difficult projects that need something non-standard.

In the long term understanding how different metals affect the behaviour of an alloy is useful, but the most important thing when starting out is being sure the metal you are using is of a known and repeatable composition; that way you can always attribute changes in behaviour/quality of the castings to your own casting techniques without worrying that it's a different metal thats cuased a change in results.

Crikey,
Sometimes wonder whether this place operates in a different dimension.
You ring up Neales or the like tell em what you trying to cast. When it arrives you chuck it into the melting pot and away you go. Simple.
Assuming you have the moulding casting skill/experience of course.
L

I do like Leon's response :-)

Leon,

Exactly, I do think people sometimes over think things…

Mike

No one ever accuses me of thinking let alone over thinking…………
L