Jump to content

Clay mixture dilemmas


Recommended Posts

Hello, Together. I have a bit of a quandary. I have been trying to mix together a clay slurry for clay-tempering some of Aldo's 1075. However, once the clay dries, it also cracks and flakes off, becoming useless. How do I not have this happen? Is it the mixture of the slurry I am using? Is it just the clay itself?

Link to post
Share on other sites

hmmm. ok. Are there other basic additives I can use? Such as ashes, charcoal or something similar? I read that some japanese smiths use a blend of charcoal, clay, ashes and water. Not that sand isn't available. That will work.

what ratios should I be looking for?

Link to post
Share on other sites

My Ace hardware closed down, and my supply of Rutlands. I have enough to last for some years, but since I'm doing a demo next month on hamon using various materials, I've been doing a little checking on alternatives. If your hardware store carries DAP High Heat Mortor, give it a try. Comes in a caulk gun tube and has the properties I like in a blade clay, smooth and sticky.

 

Dan

Link to post
Share on other sites

Thanks Matt, that had not occurred to me. Head slapping moment.

 

Don't know if it's true, but the wife tried to pick up a pint of the Rutlands before the Ace closed down. The salesperson said something to the effect "oh, we're having trouble getting that anymore". Like there's a ban on it due to chemicals in it or something. It'd be my luck that it'd be outlawed or something. Might just be a lack of sales thing at Ace too.

 

Dan

Link to post
Share on other sites

hmmm. ok. Are there other basic additives I can use? Such as ashes, charcoal or something similar? I read that some japanese smiths use a blend of charcoal, clay, ashes and water. Not that sand isn't available. That will work.

what ratios should I be looking for?

Brice, sorry I've taken a while to reply. I've tried the charcoal, clay, ashes, and water mix, and have had varied success with it. Sometimes it cracked, sometimes it didn't. Something to remember about a lot of Japanese clay is that it tends to be very coarse. Western potters hoping to imitate the look of Japanese wild clays often resort to kneading in bird gravel(to imitate Shigaraki bodies especially), sand, or other coarse media. I didn't remember that when I was playing with the traditional mix, and I think my failures were due to using too fine a bodied clay (the finest mesh fireclay they had :P). I'll confess I use satanite now. :wacko:

 

Try the traditional mix, but toss in some of the additives I mentioned. For example, cut your clay content by 1/3 and substitute that 1/3 with sand or grog (grog might be better, but use what you have). Charcoal and ash won't do much for shrinkage, I don't think. My suspicion is that the charcoal is there to add porosity to the clay as well as prevent decarb, and the ash is there to make the clay a little more sticky at temp. Unwashed wood ash is a little silica, and lots of flux.

 

Rutlands is something I've never tried, but given the discussion above (and on other threads), I'd have a look for it. Sorry if all this came too late, I've been in the sticks this past week.

Edited by Tyler Miller
Link to post
Share on other sites

My 2c.

I clay coat all my blades in a mix of local fine clay similar in texture to a potters clay and fireplace ash.

I sift both through aluminum window screening and then mix by volume about 60% ash and 40% clay.

Apply a thin super watery layer over the whole blade and dry (speed up a little with a propane torch if in a hurry). I found this step essential to keeping the clay intact during subsequent drying, but I feel it also provides the edge with some protection from decarb etc.

Then coat slightly thicker mud on the spine for the effect you are intending and dry (also with a torch if needed but slowly so the moisture evaporates before the surface glazes).

I then run it through a normalizing cycle, for two reasons. First it ensures that the clay is fully cured and allows inspection to be sure it didn't crack up. Second, I use it as a "dry run" to get the visual of descalescence for that particular blade.

When using a water quench, this clay tends to blow off, but it stays long enough to do the job. With an oil quench I usually have to get the clay off with a wire wheel as it seems to set in place like a cast "marble" counter top.

Experiment a bit and re-post what you end up with, I'd love to see what else works!

James

Link to post
Share on other sites

Thanks a bunch guys. Tyler, no worries on time. I teach full time during the week, so it was largely academic for a while, since I wouldn't have time much either. James your directions are also well taken. I'll give both a try. So, more wood ash, less clay and maybe some sand in the clay to aid minimizing shrinkage.

Let's see what happens. Also, I have to remember that I live in a mostly arid climate and that affects the way things dry too. This week will be good for those kinds of issues, though. We just got our annual average of rainfall in the last week.

Best regards

Brice

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...