Additive A (Type 2) in Ceramic / Clay

admin | Clay / Ceramic | Friday, March 21st, 2008

Additive A is a Lignosulphate, mainly used to produce plasticizers for the concrete, cement, and brick industry. I experimented with Additive A/ Type 2 in my porcelain for several months… I was able to acquire a 40 lb minimum at one point; however in the U.S., you may have to purchase hundreds or even thousands of lbs at a time from Borregaard LignoTech.

I was attempting to use Additive A -Type II to enhance my clay’s green strength, but found only marginal strength increases until the ware dried completely.
On that note, if you add more than just 1-2% and let it go to bone dry, it will dull even the best steel trimming blades within minutes. There is also a thin, but even harder, transpiration produced outer crust that is nearly impossible to cut through (imagine trimming dense plastic or wood).

As I said above, it is used as a plasticizer. But there are certainly better options when aiming for increased plasticity in clay (V-gum, CMC, MgSO4, Ball Clay…), so if this is the goal, Additive A wouldn’t be my first recommendation. It’s also important to note that lignosulphates are used as a deflocculant, which under normal conditions is the last thing you’d want to add to a throwing body.
The plasticity that it yielded was an odd one. It felt more like throwing a slime infused low-fire Redart body (sorry, best description I can give). It was neither naturally plastic or “rubbery”, but had a feel all it’s own.

I have heard of pottery studios and classrooms using small amounts (around 0.5%) of lignosulphate products to keep greenware from chipping –especially in terms of a public or commercial environment where pieces are handled often. However, the trade off can be difficult to get used to.
Right away, the resulting Additive A clay I mixed up smelled like dog food –and shortly thereafter, like dog “dood“! :)
I found the clay to work best after about 1-2 weeks of aging, but the smell permeated my skin and lingered on my hands for hours… sometimes even days. After pugging and aging for just a little over a month, the resulting clay had developed a non-plastic “black rot core” that was difficult to wedge back into a throwable condition.

Additive A will destroy the water absorption benefits of plaster, wood/Masonite, or bisqued tile throwing bats. In terms of casting slips, it will have the same result on plaster molds. A container with a 1/4 pound of liquefied Additive A once spilled onto my concrete studio floor… the resulting sticky mess took about an hour to clean up, & the stain is still visible (hey, I was gonna seal the floor anyway…).

I was also able to acquire some small samples of Lignotech’s Goulac and Ultrazine NA products. Although I experimented less with these, my limited experience with them did not make me want to continue.

Further Info:

DigitalFire Article: Additive A

“What Every Pottery Should Know” By Jeff Zamek

1 Comment »

  1. Yeah, your assessment hit the nail on the head……

    Additive A certainly will make your clay rather skunky after a few months……

    It doesn’t smell that good when it’s fresh…… but give it time……

    That strange black mold…… I know exactly what you’re talking about…..

    It’s rather harmless……. I’m pretty sure it’s derived from cornstarch, or something like that……

    I’d reccomend liquefying it, if you choose to use it……. What you say about trimming….. 1-2% rock hard…. sounds about right……

    Something like vee gum or bentonite of some sorts is probably a better bet, as far as a porcelain plasticizer……

    Comment by Christian — January 9, 2009 @ 11:31 pm

RSS feed for comments on this post. TrackBack URI

Leave a comment

Powered by WordPress | Theme by Roy Tanck