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Enamel Chemistry?


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#1 Tyler Miller

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Posted 13 January 2014 - 12:23 AM

I feel a little silly for asking this, but I thought I'd ask since there are so many glaze chemistry experts here.

 

In addition to pottery, I make knives and swords.  A few months ago, I found a Greek dagger from the hellenistic period I fell in love with (Link).  I'd like to reproduce it with silver rather than gold (I'm poor and gold is expensive).  I thought I'd ask about the enamels here since they're so similar to glazes.  It's likely silly of me to try to make my own, but I'm one of those types who would rather make things myself than buy them if possible.  There's also a practical reason for this as hard silver solder flows at the same or lower temperature than commercial enamels.  Hard solder flows at 1450 F, commercial enamels fire at around 1400-1500.

 

Given that the COE of commercial enamels(oops! that said glazes before) is about 258-360 (cubic expansion), could I formulate a homemade enamel with a melting point below the flow temp of hard solder from commonly available glaze materials?



#2 Tyler Miller

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Posted 13 January 2014 - 02:19 AM

I believe you're right about the inches per degree C, but it's the scale I'm familiar with.  COE has been a blindspot for me for a long time.  I've usually relied on glaze simulators to figure out COE--the one I use employs the same scale.

 

Edit:  Sorry, I made a major typo, above should have said commercial enamels have a COE of 258-360, not glazes.  I've corrected the mistake. 

 

A low expansion frit may be the key, or a source of boron without soda.

 

Thanks for your input, Norm.



#3 Mark C.

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Posted 13 January 2014 - 03:13 AM

I think of the brass sections with cloisonné enamels  fuzed to them-the make up a strong matrix for a knife handle over silver not sure about that?

My cloisonné is from the orient and is on pottery forms and is very strong.

I did some enamel work back in another life as a kid on copper sheets-more art program hands on. If the copper bends the stuff pops off.

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#4 Tyler Miller

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Posted 13 January 2014 - 03:01 PM

Thanks Norm.  50/50 flint and boric acid, plus 5-10% EPK appears to put me right in the ballpark.  It remains to be seen if that is a robust glass, though.  But I have all those things, so I'll be trying it once I can get some copper test plaques soldered up.  I'll post photos of the results, success or failure.



#5 JBaymore

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Posted 13 January 2014 - 07:20 PM

Tyler,

 

Swords huh? I'm an Iaidoka. I own a number of Iaito and Shinken.

 

best,

 

..................john


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#6 Tyler Miller

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Posted 13 January 2014 - 07:59 PM

John,

 

I'm in the process of polishing this tanto made from w-1 right now (sorry for the blurry photo- butyou can barely make out the hamon):

 

Attached File  tantorough.jpg   241.46KB   0 downloads

 

The lines are in no way traditional, a "gaijin-to" is what another maker would call it. :)

 

I'm working on it as well as a wakizashi, that I don't dare photograph until after heat treating it for fear of bad luck, as practice pieces for this home-carburized steel I'm slowly welding up into a blade.

 

Attached File  lump steel.jpg   253.03KB   0 downloads

 

When I get the enamel process down for its handle, the Greek dagger will be made of similar bloom-steel material.

 

-Tyler



#7 JBaymore

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Posted 13 January 2014 - 08:15 PM

Gaijin-to :lol: :lol: :lol:

 

best,

 

..........................john


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#8 Benzine

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Posted 13 January 2014 - 09:10 PM

I've said it before, John is a borderline Jedi.


"Anything worth believing, is worth questioning"

#9 JBaymore

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Posted 13 January 2014 - 09:50 PM

I have not yet constructed my lightsaber.  :ph34r:

 

best,

 

..........................john


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#10 Tyler Miller

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Posted 17 January 2014 - 01:47 PM

Well, I've spent a few nights fiddling with the glaze simulator. This is the test batch I've come up with

 

95 g flint

18 g EPK

100 g boric acid

5 g dolomite

2 g soda ash

 

I'm going to use the method of fusing the batch in a crucible, then dumping into water to obtain a frit because of the water solubility of the boric acid.  I'd love any criticism or comments you guys may have.



#11 jonnie

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Posted 24 March 2014 - 07:41 AM

Dear Tyler and all,

 

I hope Tyler will not mind me adding questions on a related theme...

 

I am interested in enamelling copper plated steel - enamel stockists always seem to supply either a special base coat for steel ( onto which they say regular copper enamels can be used ) or a specialised range for steel.

 

I ask myself whether this is a bonding issue or a thermal expansion issue as this will determine whether a copper enamel or a steel enamel should be used to enamel copper plated steel.

 

My guess is that its to do with bonding

 

1. Most online sources of expansion data suggest that steel is actually closer in terms of expansion coefficients to most glasses than copper, I am not sure about enamel frits, I am still struggling with the kind of COE Tyler mentions "258-360 (cubic expansion)" compared with the data presented (say here)

 

http://hyperphysics....bles/thexp.html

 

2. If its all about expansion then its interesting that a thin layer of "steel base coat" can then reportedly iron out the imcompatiable expansion rates of the materials either side ( steel and regular copper enamel ).

 

Please rip through my inexperienced guesses.

 

I know the obvious answer is to suck it and see but I have significant investments in time and cash ahead of me and I want to start on a path that is more likely to succeed.

 

Advanced apologies if I have hijacked the thread - I am a newbie but I did figure this was sufficiently ontopic.

 

I would also like to ask questions regards how pigments intersperse in frits at different temperatures as I am very much intested in making subtle changes to the colors of purchased enamels but I think I should probably start a new thread for that one.

 

Jon

 

 

 



#12 Tyler Miller

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Posted 24 March 2014 - 11:15 AM

Jon,

 

my suspicion is that it has to do with base metal reactivity and bonding.  Copper and steel oxidize differently and would react to the enamel fluxes differently.  Discolouration due to oxidation is always a possibility in enamelling.  Laying down a steel "base coat" or using a differently fluxed enamel would be a solution.  You cannot put glass of two different COEs over one another and fuse them, they will tear themselves apart.  The temperatures involved with enamelling are not, to my mind, hot enough to get the glasses to mingle in any way.  In fact, this would be an undesirable result as the colours would run into each other. Therefore I don't think it's a COE issue they're compensating for.

 

I got my COE values from a commercial enamel available through a jeweller's supply.  I reverse engineered my own recipe from that COE. The goal is not to match the COE of the base metal exactly, but to provide some compression.  This is what Mark C. was talking about.  Simple enamel on copper sheet is a weak bond without some sort of compression. You must remember that steel is a very new (200-250 years) base metal, while gold (used the longest), silver (next longest), and copper have been used for thousands of years.

 

I do think your best course of action is to contact the manufacturer to see what they recommend and then, as you say "suck it up and try it."  It's true that you've got some time and expense ahead of you, but enamel frit is going to be be absolute least of your costs.

 

Despite my batch above for my own enamel frit, I'm going to be trying it against a historical lime-soda glass batch from the Alexandrian period, a modern lime-soda glass, as well as a borax-fluxed borosilicate to see how it performs in the presence of soda.  Testing is the only way to ensure a suitable result.



#13 jonnie

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Posted 24 March 2014 - 02:10 PM

Jon,

 

my suspicion is that it has to do with base metal reactivity and bonding.  Copper and steel oxidize differently and would react to the enamel fluxes differently.  Discolouration due to oxidation is always a possibility in enamelling.  Laying down a steel "base coat" or using a differently fluxed enamel would be a solution. 

 

Therefore I don't think it's a COE issue they're compensating for.

 

Thanks Tyler - it would be great for me if your suspicion is correct as that would suggest that copper that has been electroplated is as good as regular sheet copper (with a few assumptions of course!).

 

>>"It's true that you've got some time and expense ahead of you, but enamel frit is going to be be absolute least of your costs".

 

Yup - I am tying together several techniques and each has questions and ultimately requires me to invest to get the right gear and take the leap. 

 

I guess the reason I dont want to rely only on experimentation and observation is that the finished products will be sold ( one man artisan business ) and I figure that just because an enamel "looks" ok it doesnt mean that the bonding is as good as it could be or that fatal stresses are present just waiting to make the whole thing go "ping" when someone knocks it so I would like to understand whether metal-enamel bonding or COE is the dominant issue here.

 

Appreciated your reply!

 

Jon



#14 Biglou13

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Posted 24 March 2014 - 08:49 PM

Might be a cheat

But the technology behind polyurethane enamels, is amazing. And colors have come along way. Eg. Polane t./ dura coat

Along with finishes like cera kote.

While not traditional enamel, might be worth looking into
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#15 jonnie

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Posted 25 March 2014 - 04:30 AM

Might be a cheat

But the technology behind polyurethane enamels, is amazing. And colors have come along way. Eg. Polane t./ dura coat

Along with finishes like cera kote.

While not traditional enamel, might be worth looking into

 

HI Biglou

 

Interesting searches on these products !

 

Not sure about the high temperature stuff but the others I believe are polymers ( resins ) which are sprayed - not unlike a "2pak" car paint. I looked into

2pak paints but the toxicity issues put me off as the catalyst is often a cyanate compound - one thing to layer by painting ( for instance fibreglass ) but another

to atomise in a spray gun which is a game changer - probably ok to use a spray can now and then but I wouldnt want to be exposed on a daily basis.

 

Enamel does contain heavy metals but the way I use it is pretty safe, hand application (no spray) and wet grinding (no dust) with water filtration to remove dust before the water re-enters the environment.

 

Thanks these are certainly interesting leads and I will dig a bit deeper.

 

 

 

 



#16 Biglou13

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Posted 25 March 2014 - 09:18 PM

There are prople painting on dura kote / polane t, an sanding. But spraying us more the norm. I may still have some . Once product is cured, imagine its like non leaching glaze and relatively safe. Eg. Resin cured. Cera kote cures at 300f. To amazingly sturdy surface/ finish.
Caution big brother is watching.
The beige is blinding!!!!!!
The middle of the road is boring

The true sign of intelligence is not knowledge but imagination.
-Albert Einstein

#17 jonnie

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Posted 26 March 2014 - 04:22 AM

There are prople painting on dura kote / polane t, an sanding. But spraying us more the norm. I may still have some . Once product is cured, imagine its like non leaching glaze and relatively safe. Eg. Resin cured. Cera kote cures at 300f. To amazingly sturdy surface/ finish.

Yes you are probably right once cured but spraying really does up your potential exposure - I regularly use fibreglass and cyanate hardners in paint brush application (non spray) the problem with spray is everything goes airborne not just volatiles - occassional use  for me is fine but I dont want occupational exposure without a whole lot of investment in spray booths and so on.



#18 Biglou13

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Posted 26 March 2014 - 04:42 AM

Yeah for commercial exposure or more than ocassional .you'll need all the safety stuff. Mother only time I used it was breezy day with long sleeves mask and eye pro. any spray process on more that occasional use needs all the safety

Keep us posted
Caution big brother is watching.
The beige is blinding!!!!!!
The middle of the road is boring

The true sign of intelligence is not knowledge but imagination.
-Albert Einstein




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