What use is sugar soap?

[Another John]

I asked this before, but some time ago because my news server doesn't have the thread. I've forgotten what people's comments were.

Sugar soap is sold as "the perfect preparation for painting ... simply wash over the area to be painted .... no need to rinse ... provides a key for the new paint..." etc etc.

Well every time I use it (including this evening), I can never detect the slightest difference in the area being prepared. Sure, it's cleaner (as indeed it would be if I'd washed it over with warm water) but I can neither see nor feel a "key" for new paint. I'll be undercoating before glossing, but I do wonder if I can miss out the sugar-soap bit in future.

Any comments folks? Ta, John

[Chris Hogg]

This may interest:

[ss]

I have to agree from my experience. I reckon a couple of quick passes with fine sandpaper will give a better key.

[PeterC]

Looked at once - said "rinse thoroughly". Only way to do that is with a hose pipe! Used Star Drops with good results (water-based gloss on a hand rail OK after about 22 years), but the mdern version seems weaker and might not be the same stuff at all.

[Thomas Prufer]

I have used TSP, trisodium phosphate, containing just that, not an imitation.

This will take off grease, and it will also etch (most/many/not necessarily all) oil-based gloss paints -- and also glass, sometimes...

It most definitely needs to be washed off carefully, and the trouble this causes needs to weighed against the work savings vs. a wipe with washing-up and/or sandpaper.

Thomas Prufer

[stuart noble]

+1. TSP used to be the main ingredient but, since the outlawing of phosphates, it's just surfactants and abrasive. Was only ever justifiable on greasy surfaces

[Another John]

Well (reading the Wikipedia article that Chris pointed us to) if it's TSP, then rinsing off would indeed seem advisable. However the bottles of sugar soap that I have had now and in the past have always said "No need to rinse!"

This discussion has been useful for me -- thanks chaps. I won't be using it in the future -- just the more traditional methods of cleaning and keying old gloss paint.

Cheers John

[Thomas Prufer]

Dishwashing machine detergent is a useful substitute for TSP. Cuts grease, and, like TSP, may roughen paints. (Another one to try is soda -- sodium carbonate).

Thomas Prufer

[tabbypurr]

last time I looked it still contained TSP.

NT

[harry]

It's primarily used in kitchens to de-grease walls & ceilings etc. prior to repainting. 'Spect there's better stuff nowadays.

[Mr Pounder Esquire]

It worked well in our kitchen.

[rick]

I find it a great cleaner .... is excellent for prep of walls before painting .... really cleans them well

[ddowning83]

Yes, I've been familiar with it from a young age. It's primarily washing soda which is very alkaline and cuts through grease. The 'sugar' bit refers to the abrasive material added. You may want to wash dirty woodwork before you sand down. Perhaps walls are stained, which you want to clean as you don't want stains to bleed through. However, you can get away without using it. I've just bought some TSP. I wonder if it's more effective than sugar soap.

[Dave Plowman (News)]

The paint this post refers to will have fallen off by now. ;-)

[Scott]

Does it not also exclude some ingredient (phosphate?) that is bad for paint?

[Andrew]

If it was water-based gloss or cheap 'emulsion' paint, sugar soap removes it very quickly. Doesn't do your skin much good either.

[Andrew]

Since the whole point of using it is to as part of the overall preparation for repainting, that's not such an issue.

very effective at removing nicotine from painted surfaces.

[ddowning83]

Well, since I got it from eBay (2 kg) from a Chemical company I'm presuming it's true Na?PO?. I've actually emailed them for the SDS to be sure. I'm presuming the phosphate will have a different effect than carbonate/s found in sugar soap but I guess only experience will tell.

[ddowning83]

Haha, no doubt.

[ddowning83]

That's good to know.