Washing a crucible

[farmertim]

Hello all
farmertim here, relatively new to off hand glass blowing (4 years), just found out my supplier is changing glass cullet and will need to "wash my crucible" prior to using the different glass they are supplying. Google search not helpful, and did not find it on the newbie section. Can anyone fill me in on the process?
Thanks

[BlairArtGlass]

Add a coffee can of the new glass to an mostly empty pot and let it melt. The use a ladel and pull it up the walls to "wash" down any of the old glass in the pot. Ladel anything you can out, and then repeat a couple times to eliminate as much of the old glass as possible. I've never personally performed this operation, but was recently instructed to do it on a crucible we are planning on using.

[farmertim]

Thank you so much. The place I get the glass from was not of much assistance. By the way, small world, my last name is Blair:)

[BlairArtGlass]

That is pretty funny, good luck with the project.

[BORO]

If your changing from from soft glass to boro, I dont know what issues that might cause.

When I help break in a new crucible or swap colors , we usually just fill it full of clear, melt it, and pull it all out.

If it had another color already in it, its important to pull as much as you can from the bottom of the pot. Ingredients /coloring agents tend to be heavy. This creates a more concentrated color mix at the bottom of the pot. It is for sure tedious to get the last little bit out. Your moil (glass gather) can only pick up so much as it only touches the bottom of your gather. You will never get it all, but you can get close. I kinda make a bell shape moil , so I get more surface area on the bottom where I contacts the glass in the pot.


I never felt like I "wash" the old stuff off, as much as you just coat it with a thin separation layer of clear.


If your just remelting a color its not as big a deal to have it perfectly clean. Your just melting the air out and pulling it.


If your batching color from chemicals and elements, you need to mix it quite a bit. You will end up pulling material /old glass from the walls. Similar to mixing cake batter in a mixing bowl. You will touch the sides of the pot in order to mix it all.

If the old color was a color with silver for example, it could contaminate a new run. Also, Some elements can clump and make hot spots that can deteriorate the crucible. It just depends( perhaps I'm getting too specific) Its probably common sense, but colors with similar ingredients tend to do better sharing crucibles.

A.k.a. things " can" happen. Like anything, its a learning curve.

Also crucibles themselves do break down over time. They will add stones, or " white streaks " that kind of look like clouds of bubbles. Certain colors will kill the crucible faster. If you need to cook hotter, or ingredients that create hot spots....

If your just remelting.... Its a lot less to worry about.

If its a new crucible, just fill it with clear, and pull it. Or coat another color with it. However you get it out, Its still fine to use for something else. Re-melt it again, whatever. (with in reason)



Edit:
The o.p. peaked my interest. How is the old glass and new glass different ? is it coe 33 ?
If the o.p. is vague because its top secret, that's cool too

[BlairArtGlass]

Based on the OPs post he describes doing "off hand glass blowing". I took that to mean he was working soft glass from a furnace. I had never heard of washing a pot until I started to learn about soft glass work. It seems to be common in the industry to "wash the pot" anytime the clear brand gets changed just incase there might be coe differances. I'm under the impression that while you may never notice an issue if you don't that it would sure suck to ruin 100lb+ of glass if there happen to be a coe issue between the new and old types of glass.

[BORO]

+1 ^

I'm always learning.

I guess i just get exposed to a lot of "off hand" boro work. My fault for assuming.

I'm really surprised the coefficient could be different from the same company. At least not all the time.
I can think of a lot of reasons why it could be an improvement. I'm just surprised.

I often day dream about how long the equipment might last if you only had to heat it to "soft glass" temps..... mmmmmmmmm happy little furnace.

[Swim]

I am in the hot shop every once in a while, and of course work boro daily, and any work done with your hands is off hand. GOing completely off of other peoples jargon without assuming anything, the only work that is not off hand is done with a lathe.

[BlairArtGlass]

I'm certainly not trying to be a know it all because I'm no expert on this. However I have never heard someone refer to lampworking or torch working as "offhand" even though you use your hands. I have only seen or heard "off hand" used to describe furnace work with metal blow tubes/punties and a glory hole. Obviously you can work boro in that method but its much more common to see soft glass worked that way. So I definitely was assuming a few things with my answer but hopefully I assumed correct and provided good info to the OP.

[Swim]

I am totally willing to sell mine and negotiate on mine now, by the time I have my shit paid off and I am into the summer, I wont wanna sell, and that is better overall, to keep my 40, they are fuckin tits.... also the vac stacks were on the phantom, not the 40. It seems like you would want the biggest fire possible on a large vac stack.... and why not?? unless you dont have alot of swing on your lathe, that was the problem for me. On my first vac stack walk through with an experienced blower, we used a 65 mm (not on my lathe) and it was fucking great, however the heat almost caught the whole room on fire, then I did the next one on my 40, and it was too much heat for my lathe. Since then I did them all on my lathe with a phantom, and my bed cover does not even get hot, it takes twice as long but shit, whats 10 minutes??? I spend all the actual time prepping it up and procrastinating.

[Swim]

lol , replied to the wrong thread. I am not knowing anything either, I just remember taking my lathe class and working at glassroots afterward, and everytime I took the point out of the lathe and started working with my hands, I was chastised fro doing "work offhand" and this was before my hotshop intro, and I have still never heard the term off hand in a hot shop. What would you do not offhand in a hot shop anyhow?

[bossrigger.mm]

Once you have stripped the pot and added and removed a small amount of the new formula you should have no problems, I have done it with no noticeable effects, before I had ever done it an old timer free hand glass blower said just empty the pot and put the new glass it, gave me grief for running new glass through and removing it!

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