Sugar soap that streaks is usually the rinse
I washed the kitchen wall with sugar soap on a Friday evening and painted on Saturday. By Sunday the new emulsion had a cloudy tide mark behind the hob, and a few shiny stripes where I had let the mix dry on the paint. I thought the roller had left a lap. I wiped a stripe with a damp cloth. It smeared. The soap was still there, under the film. I had cleaned. I had not rinsed.
Sugar soap cuts grease and nicotine so the next coat can hold. That is the job. It is not a primer. If you leave it on the wall it dries as a film. Paint sits on that film and then flashes, streaks, or lets go in patches. People blame the emulsion. The emulsion was doing what emulsion does on a residue.
Rinse is a second bucket. Clean water, a clean cloth or sponge, and a wall you go over until the cloth comes away without foam. I change the rinse water when it goes milky. One dirty rinse is just spreading the soap into a thinner streak. I work from the bottom up when I wash, so the dirty run does not dry on a bit I have already done, and I rinse the same way. Then I let it dry. A wall that is still cold and dark to the touch is wet. Paint on that is a mess of its own.
A roller that sheds is usually the cheap sleeve is the coat after this. I do not roll until the wall is rinsed and dry. Fluff in a soapy film is a souvenir you cannot sand out cleanly. Lining paper that bubbles is usually the paste is why I am careful on a newly lined wall. Sugar soap on lining that is still soft will lift the face. Wait until the lining is dry, then a light wash if it needs it, then a proper rinse. Masking that bleeds is usually the wrong tape is the frame I have already taped. I keep the wash off the tape. Wet tape lifts, and then the paint bleeds on a Monday I thought I had saved.
Kitchen grease is the usual reason I reach for sugar soap. A hall with years of hands is the other. I do not sugar-soap a clean spare bedroom for the ritual. Dust needs a wipe, not a degreaser. Too strong a mix on a weak emulsion will take the old paint off in rolls. I follow the dilution on the pack, not a blob that looks serious.
UK year changes drying, not the chemistry. A cold kitchen in January stays wet. I washed on Friday because I wanted to paint Saturday. The wall was still holding water behind the hob. Summer with the window open dries the face and fools you into painting over a streak you can no longer see. I now look at the wall in a raking light after the rinse. If I can see a shiny map, I rinse again.
Skip painting the same hour you washed. Skip a single bucket you use for soap and rinse. Skip letting drips dry on the skirting and then painting over the tide. Skip sugar soap on bare plaster you have not sealed. You will raise the dust and then seal the soap in. Skip a cloth that has done the hob and then the wall. You are putting fat back on.
If streaks are already under a dry coat, I do not keep adding emulsion. I sand the flash, wash, rinse, dry, and roll a thin coat. Two more coats on soap will only hide the map until the next afternoon sun.
I do not need a different paint because the last wall streaked. I need the grease off, the soap off, and a wall that has actually dried.
If I later add a buy link here, it will be a paid promo.