Vinegar being an acid will react with the clay surface which is caustic. That will impart the two sides of the crack with more "affinity" to eventually stick together. Vinegar will also allow you to use less liquid to achieve the needed pasty viscosity of the "caulk". When I need to repair a broken raw clay part, I also include some paper tissue to the vinegar/clay paste which sort of armour the repair and also allow slower local dryng as cellulose fibers retain water for longer. Hoping I was clear enough and that these explanations help you to understand the why of the how...

Simon, I use a concoction of clay, vinegar and toilet paper for my slip. I make a batch and mix it with an immersion blender and use it for handles and any hand built pieces. I think what happens is that the slip with vinegar dries more slowly giving the pot and handle time to equalize in water content. Another trick I use with pieces like your lids is to store them for a time in a plastic box with a tight lid. Inside the box is a slab of plaster of paris soaked in water. After a time all the clay stabilizes at the same wetness which is close to leather hard. The box is also good for keeping handles for weeks if you make too many. It can be used to save pots that have gotten too dry to trim. It is an extra step but will save the pots when you get distracted. Pots with cracks held in the box can also be repaired and then slowly dried. Many student pieces go in the box when they miss a class and their pot has dried too much for trimming.

@sleachpots

8 жыл бұрын

HI John and thanks for your comments here for all to see. In my next video you will see the results !

@alisonholmans8256

7 жыл бұрын

John Blackwood

@pmicheleghouse

4 жыл бұрын

"DAMPBOX" (invaluable)

@jennifervandevooren9105

3 жыл бұрын

Thanks for this info John and Simon. When you put a “too dry” piece in the damp box am I understanding that it dampens enough to trim like leather hard? I’ll have to try it. That is my weakness in pottery - missing that sweet spot for trimming!

@triciac1019

2 жыл бұрын

Thank you for these tricks! Can you share what brand of plastic box you use?

Thanks Simon, and all the folks who added comments and their recipes. Very helpful indeed. I’ve always assumed my best option is to toss it and make another one. This will be a lifesaver - so simple and practical! Brilliant.

Thank you so much for making this video! I had a couple of pieces that had cracks and i never learned at ceramic school how to mend them. You just saved me a couple of hours of work! Thank you so much!

Thanks Simon, it is videos like this that have helped me enormously. Much appreciated

Simon and John Blackwood! Your advice could not have come at a better time. I live in the desert southwest where drying is very fast and cracks are a problem. I mixed up the clay, vinegar, and toilet paper in the blender, smooshed it into the cracks of a problem pot, and wrapped the whole thing up in plastic. Will repeat is if still cracks..I hope my pot makes it. If it does not, other pots will! THANK YOU SOOO MUCH!

Hi Simon! Thanks for all you do so well! one thing I add to my vinegar and dry clay is a piece of toilet paper (fir the amount of clay you demonstrated) then I mash it up and apply it just to the crack. I scrape away some of the crack edges to make a "v" shape. This is easier to fill. Then I plastic cover the whole pot for a few days to a week. This usually works for just such a problem as yours. I hope it works for you. Those "biscuit jars" are just beautiful.

Simon, this video was great information. I just had this cracking problem yesterday and didn't know how to fix it. Thank you!

@sleachpots

8 жыл бұрын

In my next video the results I will comment on....

Simon, Great video. I also want to mention that it is even more cool watching your videos after attending one of your workshops. Now recognize your Studio. I highly recommend all the viewers to attend one. Simon you are the best! :)

@sleachpots

6 жыл бұрын

you are too kind !

Simon thank you for all of your videos and knowledge...by any chance can you post a video showing how you dry your greenware? 😊😻

Thank you, really saved our pieces today, thanks to you.

Excellent lesson. Would've never thought. Vinegar!

Thank you so much, I have the same trouble, with the fine crack, you explain so well

SO excited to try this! I have a bust portrait sculpture and not only do I have a fine crack under the nose but his shirt edge is a bit wobbly and I figured adding paper also will help bond it until it's fired but hoping no discoloration as my clay fires black (?)

Excellent excellent lesson thank you

Thank you Simon!! Trying today 💫

Hey Simon I first (like you) moisten the area and then with a needle tool push the surrounding clay into the crack and then fill in any void with slightly moistened dry clay then with a brush add water to the surrounding area then cover with plastic.

I once used vinegar to fixed something that I thought would be impossible. Amazing trck.

Hi Simon Lately I have had success using a ball point pen and tracing along the crack line between my handle and mug. Later my glaze love to pool in this crack line for a very attractive detail to my mug.

Hi Simon I have just found your site a figurine I have been making has a large crack in the side of it I used your vinegar in a clay slip fingers crossed thank you for a great video

hey there...for years my concoction really does the trick every time -- besides the dry clay, vinegar (i use apple cider v) then, the secret ingredient -- SUGAR or HONEY...now, you need to let it ferment at least a few days, but be prepared for the smell as it's quite harsh, but keep a tight lid on your container and it will last for years :) --- oh by the way, this mixture is so strong that after just air drying it hardens like steel! of course, let it dry naturally on your cracked piece and fire as normal...Never attempted to fix an S-crack in a plate or platter as that would be pushing it too far, and just toss it, and throw another! Cheers from the states

@alimarshall4120

4 жыл бұрын

Phyllis Michele Greenhouse how much sugar/honey to vinegar please?

Good video - thanks. Would be interested to see the final fired result too! Also got a lot of cracking trying to make things outdoors in the rain (help we're in lockdown UK - it has rained for about one hundred years every day...) - didn't let it dry slowly hence terracotta tiles cracked - wondering whether anything works at the bisque state? Could be an interesting serendipitous effect perhaps even if not invisible....

A good lesson,Simon. A very similar technique works for me on mug handles. Instead of mixing ground clay with vinegar I use a very small coil of fresh clay quickly dipped into vinegar and then placed against the vinegar moistened crack.I then apply a sweeping motion using a small artist's fan shaped brush. Thanks again,Simon. Be well

@sleachpots

8 жыл бұрын

Thanks Gail for 'chipping in ' , good to hear different approaches.

Vinegar is a solution of acetic acid in water, between 5 and 20 %, more usually in the lower range. Chemically it is CH3COOH. It is the most easily available mild acid. It has other names such as ethanoic acid. All acids react with bases to produce a salt plus water. There are plenty of bases in most clays, and here is one example among many… acetic acid reacts with calcium carbonate, eg limestone, dolomite, etc, to produce calcium ethanoate CH3COOH2Ca (which is a salt), plus carbon dioxide gas and water. Calcium ethanoate can bind phosphates, acting as a stabilizer. All salts have crystalline form. Crystals do not expand and contract as clay platelets do with their variations of water in between them. By converting a certain amount of the calcium mineral platelets into salt crystals, the expansion-contraction tendency is reduced, minimizing the cracks. Most clays expand when water is added to them, and shrink as they dry. Clay also expands and contracts during firing. This alternate expansion and contraction results in stress in the clay, mainly due to variations in thickness. Thin areas dry faster than thick ones. Thicker handles attached to thinner clay bodies are typical locations of stress and cracks. The stress is not evenly distributed. Compressing the clay at the crack can be a solution. Not all clays are volumetrically expansive and contractive. It depends on the mineral arrangement in them. There are 2 types: 1:1 which are non-expansive, and 1:2 ratios which are often expansive, eg smectite and vermiculite. This is the ratio of silica tetrahedron to aluminium octahedron. All 1:1 clays are non-expansive, as they do not allow water to expand the particles/platelets. In contrast, some 2:1 clays are highly expansive, allowing water to be absorbed between the unit layers due to weak interlayer forces and the polar nature of water molecules, which is then held in place by hydrogen bonding. So, choose your clays carefully with a eye on shrinkage rates and, testing your clays for shrinkage ratios, repair cracks only with the 1:1 types, simply by creating a mixture of dry powdered clay with a little high-acid vinegar.

@yaffabarelkovsky1447

7 жыл бұрын

Hi theillustriousjay, thank you so much for your explanation. I hope that I can bother you with a couple of questions: 1. I am currently using Standard white low-fire clay, number 205. I don't know if you are familiar with it. How can I tell if it is a 1:1 type? is it a 1:1 molar ratio between silica and alumina? and if so - I assume that the clay supplier would be able to tell me. 2. Regarding a higher acid vinegar: which concentration of acetic acid would you recommend? I understand that what supermarkets sell is 5% acetic acid in water. Would it be possible for you to copy your reply into my email address: yaffab1@aol.com. Thanks in advance, Yaffa.

Burnishing the area until nearly dry will compres the clay preventing recracking .

Thank you for a honest video

Naturally as you said - getting the moisture content equal at the outset is best but it seems that unless every bit is perfect in drying , it will pull, so often I will wax the whole area and plastic as well. When I learned we didn’t have wax. Also what others do with the vinegar and tp and clay works wonders. The acid /clay thing is so. I haven’t myself but a mentor said the vinegar also slows drying so that could be a test. Thanks so much for sharing everyone

Thanks so much. I can’t wait to try it on my air plant holders shaped like a horseshoe standing up!😊

Hi simon, I couldn’t think what to do about the cracks in my green ware and am in the middle of making endless butter dishes for my shop. Seeing this has reminded me thankyou so much. I seem to get cracks in the corners of the bases and lids where I put the coil to strengthen them. As you probably realise, they are slab built, it’s so annoying when it’s just the coil that has come away slightly that cracks an otherwise fine pot. Do you know of how I can add the coils without this happening. I do smooth them in very carefully but it still happens to some. Suggestions would be gratefully received. Thankyou, stay safe x

I usually do use the vinegar too, but someone else advised me to try icing sugar with a little water and dry clay mixed in. Not sure if that works better but it sure did help a few of my pots.

I have been using a small length of sissle twine to sand and compress the dust it makes into the crack. Seems to work for me.

Thank you for this video and all the helpful comments! Just tried a variation of this (rubbing alcohol in place of vinegar) on a basically bone dry piece with excellent results so far. The piece is a sculpture of one acrobat holding another up in the air so the joints were under a fair bit of stress from gravity as they dried... I was also stupid enough to make it out of b-mix which isn't really a sculptural clay (it's just so pretty!). As others recommended, I added in a square of shredded toilet paper to about 1 tbsp of crushed clay. I mixed that with the alcohol (probably 2 tsp - I went by feel, adding bit by bit until it was only just spreadable). The alcohol has much less of the acidic benefit described by other commenters with vinegar, however, it was all I had and my brief test of the resulting paper clay showed that it dries extremely quickly with little to no shrinkage so I figured I'd give it a go. The whole piece is now bone dry (including the crack patches) and showing no signs of re-cracking after only one application of the paper clay. The extra plus of this is that it shouldn't delay my firing this evening since the alcohol evaporated so quickly. I guess the real test will be how it looks when it comes out of the kiln! I'll post an update.

@crazyfish666

5 жыл бұрын

For anyone who (like I was) is searching the internet for a way to fix a bone dry crack, the above recipe was a resounding success. Just picked up my bisqued piece from the studio and there are no visible cracks at all, not even a hairline. Time from patching to starting the bisque firing was only about 3 hours so the rapid drying of the alcohol mix was great.

Mix clay trimmings and water with an immersion blender. Then add Darvan 811. This thins the slip (deflocculates it) so that you can continue to add more clay trimmings and mix with the immersion blender. You end up with a slip is very dense and has very little water in it. It's weird stuff! It is great for joining clay pieces or for filling cracks. I agree that the wet box is the perfect environment for repaired pieces because it lets the moisture content even out between different pieces.

Thanks for the video man! Great info, really! Also, 6:50 LOL

Hi Simon, I use white sugar. So the same method of breaking down the dry clay and making a really smooth paste with a little water or maybe vinegar maybe be even better. The sugar dries rock hard and fires well.

@mihaiilie8808

2 жыл бұрын

Sugar burns completely .Its just a source of carbon like straw ,toilet paper. If its underfired or for a particular reason,the carbon from the sugar makes a black area.It is used in pitfiring for that reason.

oh yeah! it helps a lot! thank you very much. best wishes, from Germany/ Bavaria..... 🎼Do 🎵Do🎶do😉

Hi! Thank you for this! Would this work for stress cracks on the bottom of the pot? I have circular cracks appearing on my dog bowls sometimes. Not the usual S cracks but circular ones.. thank you

Brilliant video thank You! Quick question, what type of vinegar? Not sure if it matters. I have this problem with around 15 mugs I've made. Put the handles on too late and all have cracks at the join. Tried to repair with some slip but cracks have appeared again. Hope the vinegar can save them. If anyone has any tips that be great 😊 it's red college clay I'm using. Thanks guys

Has el adhesivo para colocar la asa a las piezas con vinagre o sea arcilla en crema con vinagres. Saludos

I have a porcelain teapot with two hairline cracks on each side running down to the centre. Do you know if theres any chance of repairing it. Its so fragile that I feel like it's going to fall apart very soon. I haven't seen any videos for it, just hoping to get some insight if it's possible to get it repaired. Thanks

Merciiiiiiiii 🙏♥️

Love

I would wrap the handle mifdle portion in plastic and the rest of the handle up to 75% in damp newspaper paper ,over the plastic foil (just 30% of the handle length). That way the handle dries gradually and in the center under the plastic stays more wet so it can stretch a bit. I also use only paper clay for the full pieces ,but on large handles cracks also occur.

Hi Simon! You'll probably never read this on such an old video, but... I'd like to know how you made the design on the moon jar on the right of the table. I assume you used a paddle (don't know the correct term), but then how did you expand the wall that much without compressing it again? I thought it would collapse. It is a beautiful jar, as your work always is. I hope you'll teach us how to do it.

@mikeu5380

6 ай бұрын

I think he has a few videos on using paddles.

Hey Simon . . . A question please: Watching you grinding in the lid, is there an amount clearance needed between the barrel and the lid, to account for shrinkage and the thickness of the glaze? Maybe a second question: Will the barrel and the lid shrink at about the same rate in the first firing? Thanks for all you do . . .

@john.home1

8 жыл бұрын

Jeff, normally the lids are fired on the pot base and the contact area is not glazed. If they are the same thickness they will shrink the same and not get stuck. Sometimes the fired pieces will be tight and a little gentle coaxing by lightly rapping them with a stick will do the trick. Search Simons videos on kiln unpacking and you will see him demonstrate this.

@MississippiHappy

8 жыл бұрын

+John Blackwood Hey John .... Thanks for your response ........ I just have to keep practicing .....

Simon, is this technique used on leather hard pieces or bone dry? Can you still fix pieces that are completely bone dry?

@sleachpots

6 жыл бұрын

a belated reply ! ...but yes when bone dry !

Hi Simon, thanks for a great video. I understand the nature of an S-Crack is different but I am desperate and hoping this trick helps me here. I have a huge pitcher sculpture that I spent days on that was built around a thrown skeleton cylinder - it is my biggest and most impressive piece yet. The skeleton warped and an s-crack formed along the base. Do you think this is a futile repair trick with an S-crack? Thank you

@sleachpots

6 жыл бұрын

Cracking occurs because of differences in the moisture content of pieces, especially apendages that are added like in this video. Also they occur I have observed when the pot is too thick in places, like the base of a pot. I would let it dry out first then use the same treatment I did here. In this video I succeeded 100% with the mend - give it a try anyway !

@sleachpots

6 жыл бұрын

Also try adding some toilet paper into the mix like John below has suggested.

@philosopotter

6 жыл бұрын

Thanks SO much Simon! I'll let you know how I get on :)

@lindadeschnd2735

6 жыл бұрын

How did this work on your S crack?

Does apple cider vinegar work?

❤

Hi can anyone help please with advice on how to repair a small hairline crack in a bisque fired piece. I’ve made a planter and a small fine crack just a few centimetres has appeared on the edge down the side of the planter after bisque firing... Can it be repaired the same way as green ware? Thanks

@jeangarry8189

2 жыл бұрын

I have heard you can repair bisque ware with paper clay as well. It will have to go through a bisque firing again.

Some here in Japan have used gold, but it's probably silly as a "general recommendation"... ; )

Thanks for the info.. ps, feed your birds 😆

Adverts after just one minute? WTF? I have a Seth Cardew teapot where the flange on the lid has clearly (but very neatly) been reduced ever so slightly by using a grinding/sanding wheel. This tells me it wouldn't fit post firing so was 'encouraged' to fit so it could be sold.

maybe don't put the lids in the sun ? also the acid breaks into the alkali probably antibacterial too.

@mihaiilie8808

2 жыл бұрын

The vinegar its just carbon.Burns completely.

that is a horrible sound!

To much mumbling... sorry this could be 45 seconds to convey info.