Used old shelf primer and this happened, can you help?

[LauraLucht]

So, I fixed up my old kiln after a 13 year break from glass art, and unpacked some old Hotline High Fire Self Wash (powder). I didn’t really think the age of the powder would have a negative effect. I mixed w/ water as instructed, coated all four of my kiln shelves with 4-6 coats each, let it all dry completely, then fired it to 600, held for 30 minutes (watched the entire time), and this morning I discovered everything washed in my kiln went completely dark brown (burnt) including all my kiln furniture (didn’t have wash on it), and the brick inside the kiln is even a bit singed looking. It never went over 610 degrees. 
FYI, I had fired the kiln prior to this fire to 1650 degrees, and it had been fired after the elements and brick were replaced too 1400. Nothing like this happened before the freshly applied kiln wash.

A local ceramic/ kiln shop recommended I re-fire one self at 1250 with the brown primer on it to “see what happens,” I guess she thinks it could burn off? Then she said once the self is cool I should scrape it, apply new kiln wash and re-fire. My gut says I should scrape all of the shelves first and re-fire them with the kiln furniture (also turned brown), but without the new wash on it, let them cool, then apply new wash?  
I just don’t want to do more damage to these items

What would you do next?

Any advice is appreciated! 

Laura 

P.S. See photos of post cured shelf wash, full size image shows the furniture, shelves and inside kiln too.

Edited August 16, 2023 by LauraLucht
added photos and asked for help

[Mark C.]

No photos so its a bit of a guess as to what this is. You need to make your own kiln wash-use the search function  to find formulas-commercial wash is crap and made with the scheapest materials . Mine is 1/2 alumina hydrate and 1/4 calcined EPK and 1/4 EPK

In terms of burning off yours we need to see it or know about whats in it to advise. I suggest wire wheeling it off as it may be a low flux prioduct and firing hotter could bind it more to shelves

 

are you a glass slumper? or using this in a ceramic kiln?

 

Is this your product?

(24 Oz. Hi Fire Primer is a formula of alumina and low-fluxing clays. It is designed to withstand the high kiln temperatures required for glass raking (sometimes called combing). It does contain a dye which burns off when firing and will not affect your fused glass. An excellent smooth finish between the glass and kiln shelf but it is also excellent for coating mandrels for beadmaking.)

Edited August 17, 2023 by Mark C.

[LauraLucht]

Hi Mark! Thanks for your reply.  I appreciate your advice to make my own wash in future, and I will likely go that route. First, I am looking for advice on how to remedy the situation with my selves and furniture, and to do it without damaging my kiln. 

I think I have attached a photo  below this time to help you see the discoloration better, and there's an image of the product container on that image as well. Unfortunately, the container doesn't say what the composition is. Yes, I think that is the "newer" description of the same product I used, but my container is probably 13-14 years old now.

I am a glass artist.  This product had previously worked very well for me (13 years ago).  It may be a low-flux wash, however I had used it to protect my shelves while fusing glass and had never had issues with getting it off the shelf. To fully fuse glass you need to fire at between 1300-1650 degrees. I realize this is low-temp compared to ceramics, but thought it might be helpful information here.

The person I spoke to at my local shop does think the brown color will burn off and that this issue is related to the dye in the old product reacting. 

Not sure what you mean by "wire wheeling it off," but if you mean to sand the product off of the shelf, then yes. That was my gut instinct too. I was easily able to sand the material off the half shelf, but after sanding there are some  dark brown specks left in the porous shelf. My hope is that will burn off easily.

Thanks again for your advice and reply.

[Piedmont Pottery]

It looks to me like you had enough organic materials in the kiln wash to create a reducing environment in the kiln and you got a lot of carbon going into the surface of everything.  If that is correct, refiring with plenty of air available, e.g., peeps open or lid propped open just a bit, should burn off the trapped carbon.  Fire it up to your normal working temperature.

[Russ]

5 hours ago, LauraLucht said:

The person I spoke to at my local shop does think the brown color will burn off and that this issue is related to the dye in the old product reacting. 

YES.  Id try firing before i went to all the trouble of sanding and scraping.

[LauraLucht]

Thanks everyone! Scraping the wash off and re-firing worked magic! Cheers!

Edited August 17, 2023 by LauraLucht

[neilestrick]

Looks like carbon to me, and that matches up with 600 degrees. The organic materials started to burn, but it didn't get hot enough to burn them out completely.