# Cleaning brushes used for polyurethane - favourite solvent?



## Eric The Viking (15 Sep 2016)

I'm actually using stabiliser before applying masonry paint, which seems to be thinned one-part polyurethane. 

It does work well, but the instructions say to clean brushes in white spirit. This leaves a rubbery tidemark on the brush. I can loosen this with brush cleaner and remove it mechanically, but it takes ages, so I'd rather find a suitable solvent if there is one. I used to have the same problem with yacht varnish years ago, and I can't remeber what we used to do.

I have got:

White spirit,
Meths,
Acetone,
Brush cleaner (whatever that is),
Baufix "universal thinner" from Lidl, and
Xylene(!).
I can also go shopping...

I bet someone knows exactly what to use


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## woodpig (15 Sep 2016)

Have you not tried the Baufix? I've found its pretty good stuff.


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## Eric The Viking (15 Sep 2016)

Hadn't, but will now


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## thick_mike (15 Sep 2016)

When I used to formulate PU adhesives, we used esters (ethyl and butyl acetates) as solvents. Acetone will probably be a good solvent, but it's very volatile for cleaning.


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## mbartlett99 (15 Sep 2016)

Polyurethanes are cleaned/thinned with acetone. Its unpleasant and flammable as I'm sure you're aware.


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## ED65 (16 Sep 2016)

White spirit if it's just oil-based polyurethane. The secret is to use lots and lots of it; if you don't want to wash the brush afterwards don't skimp on the quantity as it's a dilution thing. 

If you want to do a second-stage rinse instead of washing after rinsing in white spirit use acetone, brush cleaner or the Baufix stuff. The difference between rinsing in white spirit alone and then rinsing a second time in a different type of solvent is like night and day. Cellulose thinners is excellent for this but you don't list it and any of the three above should work fine anyway.

In case it's not something that's crossed your radar before, wiping the brush as clean as possible before you rinse makes a big difference. We used to use newsprint back in the day for brushes loaded with oil paint, an old phone book might be used for the same purpose if you don't want to use up loads of kitchen paper.



Eric The Viking":am8zh8x0 said:


> Brush cleaner (whatever that is),


Usually a mix of solvents, sometimes with added surfactants but mostly it's the mixture of solvents that does the trick since it provides across-the-board solubility.


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## No skills (16 Sep 2016)

Try cellulose thinners, we use it at work for a lot of things - cleaning up crappy pu mastic applications is one


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## Phil Pascoe (16 Sep 2016)

Sod it. Use a throwaway brush.


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## oakmitre (17 Sep 2016)

Have you tried water ? Sounds mad but

Most masonry paints are either water based polyurethane or solvent based pliolite. The pliolite has a very strong smell.

Either way - I found this man's channel watching him make plywood boxes a long time ago. He claims to have made a Purdy brush last 10+ years using his own 1/8" cleaning method.

http://askwoodman.com/2013/07/14/how-to ... int-brush/


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## sunnybob (17 Sep 2016)

I'm with Phil.
Use it and bin it. 
Count the cost of cleaning materials and time spent...then realise its not "quite" clean enough..... lifes too short.


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## Eric The Viking (17 Sep 2016)

The brush in question is a 'special' with a long, cranked handle, and very useful. I've had the same two on the go for about six months, one for PU stabilizer and one for masonry paint (they're excellent for getting behind drainpipes and the bits that are annoyingly out of reach off the scaffold tower or a ladder. 

Rafezetter (of this parish) put me onto using oxy-action fabric cleaner (the granular stuff in a pink tub - can't remember the brand): it's magical for cleaning off water-based paints of all sorts. I've kept a favourite fitch going for well over a year, and some pricey long-bristle brushes, by soaking them occasionally.

I managed to clean the PU brush sufficiently this time using white spirit and "brush cleaner" (the liquid is blue-green, which is a bit off-putting).

Next time I'll go straight to the Baufix thinner, and acetone if that doesn't work. 

Acetone, incidentally, is brilliant for cleaning up Araldite drips or smears, as long as it hasn't actually hardened yet.

I do use "use and throw" ones, but they're horrid for actual painting, unless I'm modifying them for some special purpose (with scissors). They make handy bench brushes though for cleaning routers, etc. The next step up, with synthetic bristles, aren't too bad though.

I hate just throwing things away though. I'd far rather clean and reuse if that's environmentally better (I know it isn't always though). I managed to get OK (good enough) results from a 20-year-old tin of Trimite cellulose spray last night - feeling slightly smug on that one!

Thanks all.

E.


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## Phil Pascoe (17 Sep 2016)

If you use oil based paints infrequently get one of these
http://www.paints4trade.com/brush-mate- ... 0wod2ogBgg (not necessarily the cheapest).
You can store your brushes a year at a time, take them out and use them. I used one the other day that had been in the box for 18 months. The small one wouldn't take 4" brushes, though. Just buy a replacement solvent strip or a bottle and top it up once in a blue moon. There are professional decorators that use these who never clean a brush in its lifetime - they pay for themselves in thinners saved, let alone down time.


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## Eric The Viking (17 Sep 2016)

Good idea. 

I already do something similar: make a capital "H" shaped cut in a marmalade jar lid* with a Stanley knife. Peel back the middle bits. to leave a reasonably not-sharp rectangular hole for the brush handle. Drill brush at its shoulders. Suspend brush with nail. with just the tips of the bristles in clean white spirit. The handle blocks most of the hole, although evaporation still happens.

I tried it with acetone last week, for my cellulose sanding sealer brush. on impulse I used a disposable glove instead of a plastic bag and rubber band on top. It almost, but didn't quite work. I think the acetyl is permeable to acetone. And anyway, I'm not that keen to have a brush in the workshop sticking one finger up at me all the time ;-) 

I'll investigate those tubs/tanks further - they look like a really good idea.

E.

*I eat a lot of marmalade!


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## Phil Pascoe (17 Sep 2016)

They are brilliant. The small ones are OK for domestic use, and the beauty is that they work with a vapour, not a liquid, so you just take out the brush and paint. I saw some Purdy advertising a while back where a decorator on contract work in council houses glossed 1300 whole houses without cleaning the brush - it had about 15 bristles left.
When you work on £4 or whatever for 2ltrs of white spirit, they don't take long to justify their cost.


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## rafezetter (17 Sep 2016)

That container does look interesting - ever the skinflint though Erik (me not you  ) I've seen in pound shops good sized spaghetti food seal containers - how about trying your method of suspending the brush, but without dipping the brush in thinners and putting a babyfood sized jar in the bottom with solvent of choice, maybe the baufix, that really does seem to work on everything, to evaporate and create said atmosphere?

string line across container sealed with silicone at the holes, and drill hole in brush but cut slot to slip over string.

(you can be my small south american edible rodent


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## Phil Pascoe (17 Sep 2016)

I don't think it'll work because even if you leave a brush in thinners it will still become unusable before long. Also if you can persuade a £1 shop container to seal you're a better man than me.  You could always buy that particular vapour, though. I paid £13 + for the box - the cost of a decent brush or two - so it's not exactly wasted.


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## ED65 (17 Sep 2016)

oakmitre":34qa92yi said:


> He claims to have made a Purdy brush last 10+ years using his own 1/8" cleaning method.


That's pretty impressive with a brush of that type have to say. 

I have a few hog bristle brushes that are over 30 by now, and a few artists claim to have brushes on the go that are well older than that. The cleaning methods will vary all over the shop, from the traditional method of swishing in turps and then washing in warm soapy water, to multi-bath rinsing in white spirit or OMS to cleaning in vegetable oil. That last is an absolute winner for brushes used with oil or enamel paint, although I'm hesitant to try it with a varnish brush.


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