steff p Posted April 16, 2022 Report Share Posted April 16, 2022 hi team - hopefully someone can help ive tried 3 different engobe recipes and am mixing in green stain (in a water and stain mix) . Unfortunately it keeps coming out with white splotches . The wet ingredients look oily in each as well. I have added cmc gum but that hasn’t helped. Is dispex an idea? Thanks in advance Link to comment Share on other sites More sharing options...
Dick White Posted April 16, 2022 Report Share Posted April 16, 2022 Are you sieving the engobe mixture after adding the stain? Link to comment Share on other sites More sharing options...
steff p Posted April 17, 2022 Author Report Share Posted April 17, 2022 yes i have been sieving & mixing well each time- i noticed when i mix the stain with water prior to adding to the mix it too has the ‘oily’ surface its crysanthos brand Link to comment Share on other sites More sharing options...
steff p Posted April 17, 2022 Author Report Share Posted April 17, 2022 thanks for replying Link to comment Share on other sites More sharing options...
Hulk Posted April 17, 2022 Report Share Posted April 17, 2022 Hi Steff! Are the images you posted fired work? Just the engobe, the green part, with no glaze over it? What temp range, over what clay(s)? If you can post your recipes, might be helpful and interesting. Several of the forum contributors are good with recipe analysis. I'm seeing interesting varied green with some small black spots, looks like a low gloss, but not matte. Could you spell out the problems - I'm not seeing white blotches or an oily look, and describe the look and feel you are looking for? Just trying to help. I've been interested in engobes, but chose to explore underglaze, slip, and glazes, so far. Link to comment Share on other sites More sharing options...
steff p Posted April 17, 2022 Author Report Share Posted April 17, 2022 hi - unfortunately it wouldn’t let me upload big file images. theres a cloudy streak in the 2 left images both engobe and stain fired to midfire on a clay body called buff raku trachyte - the black dots are the melted trachyte - which i love -it gives the matte finish texture- i just can’t stand the white powdery streaks. In the far right image thats one of the engobe and stain mixes in a bucket- if you look closely the mix has a streakyness to it as well- its one of 3 engobe recipes ive tried I will upload the recipes tomorrow thanks for responding the look im after is the left 2 images minus the white streaky/ clouldy brush marks- if you zoom in you can see it clearly on the middle image Link to comment Share on other sites More sharing options...
steff p Posted April 17, 2022 Author Report Share Posted April 17, 2022 added a close up image- i will try and snap some more tomorrow too Link to comment Share on other sites More sharing options...
steff p Posted April 17, 2022 Author Report Share Posted April 17, 2022 Link to comment Share on other sites More sharing options...
PeterH Posted April 17, 2022 Report Share Posted April 17, 2022 13 hours ago, steff p said: yes i have been sieving & mixing well each time What mesh is your sieve? I'm a little confused by the colour of your brush-marks, could you be pushing/pulling anything around? Link to comment Share on other sites More sharing options...
Min Posted April 17, 2022 Report Share Posted April 17, 2022 Looks like efflorescence from soluble mineral salts. Are you using a commercial engobe or mixing your own? Link to comment Share on other sites More sharing options...
Hulk Posted April 17, 2022 Report Share Posted April 17, 2022 Ah! Now I'm curious if the white streaks wash off at all. Cool sculpture! Link to comment Share on other sites More sharing options...
Pyewackette Posted April 17, 2022 Report Share Posted April 17, 2022 I agree, it took me seeing the whole piece to even see the white streaks being discussed, but it does look like some sort of efflorescence. I actually found the little black specks more objectionable, until I saw that sculpture piece. I'm used to thinking of glaze in terms of food safety and appropriateness on utilitarian pieces. I will make the effort in future to remember the difference between something you're going to eat out of and something that is "just" art LOL! I would love to have a glaze that turned out on the piece like it looks in the bucket. That is GORGEOUS in the bucket LOL! Link to comment Share on other sites More sharing options...
Min Posted April 17, 2022 Report Share Posted April 17, 2022 38 minutes ago, Hulk said: Now I'm curious if the white streaks wash off at all. If it is mineral salts it should come off with a wash made with 1 part white vinegar to 1 part water and good scrub. Going forward if the vinegar wash gets rid of it on a fired piece I would add a tiny amount of barium carb to the engobe. I would run some tests starting with 0.3%, 0.5% and 0.75% barium carb added to the engobe, and use the least amount that gets rid of the efflorescence. I would also check the Safety Data Sheet for the claybody to see if it has barium in it also. Link to comment Share on other sites More sharing options...
PeterH Posted April 17, 2022 Report Share Posted April 17, 2022 Min Safety Data Sheet and Technical Data Sheet available viahttps://www.northcotepotterysupplies.com.au/product/brt-feeneys-buff-raku-trachyte-12-5kg/ Link to comment Share on other sites More sharing options...
Min Posted April 17, 2022 Report Share Posted April 17, 2022 Thanks Peter. I wonder if the clay “Other non hazardous ingredients…..secret” is barium? Don’t know. Think the first step would be to see if the white can be scrubbed off with the diluted vinegar, if it can then test and see if an unglazed, slipped or engobed piece gets the same deposits. Link to comment Share on other sites More sharing options...
Babs Posted April 17, 2022 Report Share Posted April 17, 2022 Looks like stuff is being picked up from claybody on application. Maybe colourants dropping to bottom of bucket.stirring between brush loads and laying on the engkbe instead of pressing it on with brush. Have you tried pouring this on instead of brushing? Tried this engobe other clays? Link to comment Share on other sites More sharing options...
steff p Posted April 17, 2022 Author Report Share Posted April 17, 2022 wow guys- thanks so much what an awesome community!!!!! Will try vinegar ✅ Know its not something on the brush dragging around as have tried it different days times & all were bisqued first I stir it a lot between tests because the crysanthos stain does sink Im testing in the next few days with : 1. dispex added 2.vinegar added & 3. dishliquid added Link to comment Share on other sites More sharing options...
steff p Posted April 17, 2022 Author Report Share Posted April 17, 2022 3 hours ago, Min said: 26 minutes ago, Babs said: Looks like stuff is being picked up from claybody on application. Maybe colourants dropping to bottom of bucket.stirring between brush loads and laying on the engkbe instead of pressing it on with brush. Have you tried pouring this on instead of brushing? Tried this engobe other clays? will try pouring & will try on other clay - great idea Link to comment Share on other sites More sharing options...
steff p Posted April 17, 2022 Author Report Share Posted April 17, 2022 8 hours ago, Min said: Looks like efflorescence from soluble mineral salts. Are you using a commercial engobe or mixing your own? i have mixed my own - have tried 3 different recipes- will upload recipes when i get to the studio x Link to comment Share on other sites More sharing options...
steff p Posted April 18, 2022 Author Report Share Posted April 18, 2022 9 hours ago, Hulk said: Ah! Now I'm curious if the white streaks wash off at all. Cool sculpture! nope unfortunately the vinegar mix scrub didn’t work Link to comment Share on other sites More sharing options...
steff p Posted April 18, 2022 Author Report Share Posted April 18, 2022 11 hours ago, PeterH said: What mesh is your sieve? I'm a little confused by the colour of your brush-marks, could you be pushing/pulling anything around? i originally used an 80 mesh sieve but after adding gum etc went through again with a 60 mesh Link to comment Share on other sites More sharing options...
steff p Posted April 18, 2022 Author Report Share Posted April 18, 2022 these are the 3 separate recipes ive tried- maybe its my epk / kaolin ?? recipe 1 epkaolin 31.6 ball clay 9.4 silica 27.4 feldspar (custer spar) 31.6 borax 2 recipie 2 epkaolin 10 ball clay 10 feldspar 8 nephy sy 2 silica 20zircopax 2 borax 2 recipie 3 18 silica 18 talc 14 neph sy 16 ep kaolin 34 ball clay Link to comment Share on other sites More sharing options...
Min Posted April 18, 2022 Report Share Posted April 18, 2022 Borax dissolved in hot water before being added? Link to comment Share on other sites More sharing options...
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