Jump to content


Photo

Underglaze, Colored Slips, Compatible?


  • Please log in to reply
29 replies to this topic

#21 Norm Stuart

Norm Stuart

    Advanced Member

  • Members
  • PipPipPip
  • 639 posts

Posted 26 January 2014 - 10:45 PM

Jon Brooks bought the Gerstley Borate name when he bought the mine.

 

Laguna Clay Gerstley Borate satisfies all of my needs at a very inexpensive price.  God only knows what he makes it out of now, but I think he does a better Gerstley Borate than the other GB substitutes.  http://www.axner.com...ley-borate.aspx

 

Our price delivered from Laguna's City of Industry site is something like $26 for a 50 pound bag.  It's considered a clay, so is eligible for the clay volume discount that ranges from 5% up to 30% depending on how many pounds you order.  500 pounds 21.6%; 1,000 pounds 25% et al.  We're about 35 miles from them.

 

What have I missed? Seems like I remember the supply of gerstley borate was closed down, and folks started using subs for it such as gillespie borate. I have a bag of gerstley from years ago, but checking SC find it is not available from them. Is it available at a decent price out there, or is it best to sub with the gillespie?



#22 Babs

Babs

    Advanced Member

  • Members
  • PipPipPip
  • 920 posts

Posted 27 January 2014 - 05:21 AM

Holly's under glaze  with 33% of a frit, does that make it a glaze?

 

Lots of terms used loosely maybe.. Underglaze usually used on bisqued pot and so needs something to help it stick and fuse to the pot ,fired low then glazed.

Slip,basically clay and colour , but because it is applied to leatherhard, usually, pots it needs altering so that it dries compatibly with the leatherhard clay.

Engobe another animal, slip glaze eeeek.

Now potters add things to make all of that work then along comes someone courting failure  ;) and puts underglaze on raw pots, slips ontop of glaze etc .Don't know what % of fluxes etc moves one of the above from one category to the other, or perhaps it is just how you use it that determines that. Or how vitrifiable it is..

Now some ceramicist can explain all of that in science speak.



#23 Pres

Pres

    Retired Art Teacher

  • Moderators
  • 1,993 posts
  • LocationCentral, PA

Posted 27 January 2014 - 10:15 PM

So Gerstley is no longer available? I only had an 80# bag I think. I am going to try tests with the Gillespie, as I have heard that it is pretty close to the Gerstley. That way my glazes should be consistent under the new one. I am not sure if there is another reasonable sub out there without restructuring the entire glaze.


Simply retired teacher, not dead, living the dream. on and on and. . . . on. . . .                                                                                 http://picworkspottery.blogspot.com/


#24 timbo_heff

timbo_heff

    Advanced Member

  • Members
  • PipPipPip
  • 171 posts
  • LocationMA / NY

Posted 28 January 2014 - 01:00 PM

Here's some actual info on Gillespie v. Gerstley borate:

http://www.sheffield...-p/rmgilbor.htm

Since the Gillespie is manufactured and not mined: it is much more consistent, repeatable  , and dependable:

The Laguana / Gerstley is from a a notoriously highly-variable vein of material. (no it is not from overseas) It can be very different bag to bag.

It's a good idea to switch to Gillespie since it is a blended material that therefore can be consistent batch to batch.

It looks a bit different than Gerstley, but since Gerstley is always different from itself, it is hard to compare.

At this link you'll seem some tests of floating blue that (I believe) Jeff Zamek did to show similarities/differences

 

Again , it is worth considering switching to the more consistent material, it takes a lot of headaches out of troubleshooting. If you use Gerstley, you should buy full bag, and do line blends to test. Then next time you need a bag, you should line blend again.

This is not necessary with the Gillespie stuff since it is going to be the same from bag to bag..



#25 timbo_heff

timbo_heff

    Advanced Member

  • Members
  • PipPipPip
  • 171 posts
  • LocationMA / NY

Posted 29 January 2014 - 01:18 PM

That's Laguna Borate, Norm, not gerstley borate. !!!

The Laguna borate is a sub like the gillespie borate is.

 

By the way there are tons and tons of the actual Gerstley borate kicking around so it is important for people to migrate to the gillespie or the laguna borate as apparently you have wisely done.

But you are going to confuse people when you keep calling the Laguna borate, gerstley borate.

If you call a ceramic supplier and order Gerstley Borate you will get Gestley Borate.

We have many ton's of it here.

We also stock the Laguna borate and the Gillespie.

Reports from most folks so the Gillespie is the better of the two subs but either is better than the original.

Neil has a nice bit on why actual gerstley is not good http://neilestrickga...ley-borate.html



#26 Norm Stuart

Norm Stuart

    Advanced Member

  • Members
  • PipPipPip
  • 639 posts

Posted 29 January 2014 - 03:53 PM

You're correct.  Laguna Clay does not sell a product called Laguna Borate, even though that product may have existed at one time.  I had assumed the Digitalfire article spoke of a current product - apparently not.   I'm certain Tony Hansen knows this because he's paid to maintain Laguna Clay's Axner website.   http://www.axner.com...ley-borate.aspx

 

Laguna Clay owns the Gerstley Borate name and the huge remaining supply.

 

The chemical composition of Laguna Clay Gerstley Borate in their PDF is very similar to the "Rationalized Gerstley Borate" Tony Hansen has on Digitalfire -- but is quite different to what Tony Hansen calls Laguna Borate and all other Gerstley Borate substitutes.  I have no idea what "Rationalized Gerstley Borate" is, but it suggests Gerstley Borate from the original producer varied from bag to bag as the material was mined.

 

I can only imagine the amusement Jon Brooks enjoys when reading twitterpated posts by envious competitors who can no longer sell Gerstley Borate unless they buy it from Laguna Clay.

 

In many posts I've said I think Laguna Clay sells horrible quality red iron oxide, and you're better served buying synthetic red iron oxide from US Pigment.  But give the devil his due, Laguna Clay is the only source of Gerstley Borate anywhere in the world and sells it at a very inexpensive price - we pay about $0.50 a pound and it works perfectly.

 

Jon Brooks provides this PDF file to clarify the sort of misinformation often posted.  http://www.axner.com...tley_Borate.pdf

 

Gerstley Borate
There have been rumors that this product would become unavailable very soon.
Those reports are wholly inaccurate.
 
The supply* will last for many years, and because it is a stockpile (not a changing source from an active mine) the chemical analysis will remain quite consistent.
 
This product has also been tested in the traditional “Floating Blue” glaze (see image) and the results were excellent. 
 
*3,000 tons or 6,000,000 pounds as of 6/18/2011
 
As John Baymore often says, "Know your materials, people."
 

That's Laguna Borate, Norm, not gerstley borate. !!!

The Laguna borate is a sub like the gillespie borate is.

 

By the way there are tons and tons of the actual Gerstley borate kicking around so it is important for people to migrate to the gillespie or the laguna borate as apparently you have wisely done.

But you are going to confuse people when you keep calling the Laguna borate, gerstley borate.

If you call a ceramic supplier and order Gerstley Borate you will get Gestley Borate.

We have many ton's of it here.

We also stock the Laguna borate and the Gillespie.

Reports from most folks so the Gillespie is the better of the two subs but either is better than the original.

Neil has a nice bit on why actual gerstley is not good http://neilestrickga...ley-borate.html



#27 timbo_heff

timbo_heff

    Advanced Member

  • Members
  • PipPipPip
  • 171 posts
  • LocationMA / NY

Posted 29 January 2014 - 04:32 PM

Sorry to high-jack this thread, but this is important:

Laguna Borate is their manufactured sub for gerstley borate : absolutely , 100% no doubt

 

See the Laguna catalog !!!!!! : http://www.lagunacla.../lcc_dryraw.pdf

Look at the list of materials there: it clearly says for Laguna borate:

A specially formulated flux containing a high percentage of boron. This material mimics the fluxing characteristics of Gerstley Borate: "

 

and even in the link you sent http://digitalfire.c...gunaborate.html : if you read it it is quite clear that it is what I am saying:

 

Laguna Borate Laguna Clay claims this is almost identical in every glaze they have tried and is less expensive than Gerstley Borate was.."

"Laguna Borate has the distinction of being the least expensive substitute available. "

 

Yes, the remaining stocks of of Gerstley are owned by Laguna: it is still sold by them and others as Gerstley Borate.

The link you posted for the Gerstley B chem analysis  is for of the remaining stuff that came from the mine: (in it they claim that is consistent, but we all know it's not very consistent)

The stuff that is consistent is the manufactured versions ! Laguna started making the sub when everyone else did ... they then bought the remaining stocks of the natural stuff as well.

 

On Tony Hansens page (http://digitalfire.c...ubstitutes.html) he shows the chem analysis of the manufactured subs, including Laguna Borate, vs the actual mined stuff.

 

So Norm, if you have been ordering "Laguna Borate" from them, you are using the consistent manufactured sub,

if you have been ordering "Gerstley borate" from Laguna then you are using the stuff from the mine.

Both products say laguna on the bag: both are available, but are not the same material.

 

Yes, it is a bit confusing,that's why it's important that people get the difference here, especially since so many people love the floating blue glazes!

The long and short of it is : if you can buy the original mined GB, don't do it. Get one of the substitutes like Laguna B or Gillespie B: they do what you need and are the same bag to bag.



#28 Marcia Selsor

Marcia Selsor

    Professor Emerita, Montana State University-Billings

  • Members
  • PipPipPip
  • 3,842 posts
  • Locationwhere Texas, Matamoros, Rio Grande and Gulf of Mexico come together.

Posted 29 January 2014 - 04:33 PM

That underglaze recipe actually came from Val Cushing's handbook but is written as 25% Frit 3110, 25 epk and 25 stain. Total is 75.
So it makes more sense to use 1/3, 1/3, 1/3. I have posted this here several times over the years as well as on Clayart. It works as a low fire underglaze but it will sometimes go higher depending on application and which stain is being used.

Marcia

#29 Matt Oz

Matt Oz

    Advanced Member

  • Members
  • PipPipPip
  • 268 posts
  • LocationMichigan

Posted 29 January 2014 - 04:37 PM

Laguna  did make a substitute called Luguna Borate but they discontinued it.

Short PDF with announcement. http://www.lagunacla...y/lagborate.pdf

So that explains all the confusion.



#30 Norm Stuart

Norm Stuart

    Advanced Member

  • Members
  • PipPipPip
  • 639 posts

Posted 29 January 2014 - 04:58 PM

Thanks for  posting that, Matt Oz. 

 

So, there was a "Laguna Borate" product at one time, which is no longer sold.

 

The Gerstley Borate I purchase from Laguna says Gerstley Borate on the bag - I can post a photo.

 

The chemical make-up in the PDF file closely matches "Rationalized Gerstley Borate" on Digitalfire, but is quite different to Gillespie Borate and other substitute GB products.

 

Laguna Clay made a smart move when they purchased the remaining supply after the manufacturer decided it was no longer worth their while to sell it.  We like the original Gerstley Borate product and still buy it from Laguna Clay.

 

Laguna  did make a substitute called Luguna Borate but they discontinued it.

Lame PDF with announcement. http://www.lagunacla...y/lagborate.pdf

So that explains all the confusion.

 

 

 

Sorry to high-jack this thread, but this is important:

Laguna Borate is their manufactured sub for gerstley borate : absolutely , 100% no doubt

 

See the Laguna catalog !!!!!! : http://www.lagunacla.../lcc_dryraw.pdf

Look at the list of materials there: it clearly says for Laguna borate:

A specially formulated flux containing a high percentage of boron. This material mimics the fluxing characteristics of Gerstley Borate: "

 

and even in the link you sent http://digitalfire.c...gunaborate.html : if you read it it is quite clear that it is what I am saying:

 

Laguna Borate Laguna Clay claims this is almost identical in every glaze they have tried and is less expensive than Gerstley Borate was.."

"Laguna Borate has the distinction of being the least expensive substitute available. "

 

Yes, the remaining stocks of of Gerstley are owned by Laguna: it is still sold by them and others as Gerstley Borate.

The link you posted for the Gerstley B chem analysis  is for of the remaining stuff that came from the mine: (in it they claim that is consistent, but we all know it's not very consistent)

The stuff that is consistent is the manufactured versions ! Laguna started making the sub when everyone else did ... they then bought the remaining stocks of the natural stuff as well.

 

On Tony Hansens page (http://digitalfire.c...ubstitutes.html) he shows the chem analysis of the manufactured subs, including Laguna Borate, vs the actual mined stuff.

 

So Norm, if you have been ordering "Laguna Borate" from them, you are using the consistent manufactured sub,

if you have been ordering "Gerstley borate" from Laguna then you are using the stuff from the mine.

Both products say laguna on the bag: both are available, but are not the same material.

 

Yes, it is a bit confusing,that's why it's important that people get the difference here, especially since so many people love the floating blue glazes!

The long and short of it is : if you can buy the original mined GB, don't do it. Get one of the substitutes like Laguna B or Gillespie B: they do what you need and are the same bag to bag.






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users