How do you know when a bottle of mineral spirits has gone 'bad'?
Thanks in advance for your help.

When it taste funny:jester::laughing: Just kidding

 

I have never seen MS go bad. If it is used, the paint in it will cloud it, but it eventually settles to the bottom. Maybe that is what you found.
Or perhaps it wasn't MS at all. I'd say smell test it, but I bet you probably don't know that smell as well as I do-

One other thought- there is a "non flammable" MS equivalent that is white. Usually comes in a white plastic jug.
Worthless in my opinion, but it might look like that.

 

I have never seen MS go bad. If it is used, the paint in it will cloud it, but it eventually settles to the bottom. Maybe that is what you found.
Or perhaps it wasn't MS at all. I'd say smell test it, but I bet you probably don't know that smell as well as I do-

One other thought- there is a "non flammable" MS equivalent that is white. Usually comes in a white plastic jug.
Worthless in my opinion, but it might look like that.

Yes, this is a white bottle of 'odorless' mineral spirits - Klean-Strip Green. The liquid is also white.

I let the brush sit in the jar of it for about 4 hours and cleaned it out with a paint brush cleaner, then some soap & warm water.

The stain never really dissolved, it just came out of the brush in small globs and it took a long time to get it all out.

Thanks for the replies everyone.

 

That sounds normal to me. If the brush sits for a while stuff will collect on the bristles. It will dissolve back into the spirits. Spin it out and rinse again until the spirits run clear.

 

Agree have never known of MS going bad. After cleaning brushes we always let it set awhile the paint would settle to the bottom we then pour out the good stuff on top and keep reusing it.

 

Tool hit it. Pots of thinner brushes collect sludge on the bottom and it also coalesces on the bristles. Spin it out and rinse until clean.

 

Yup. What you are seeing is the product you used getting partially dissolved on the bristles because you did not clean it out. If you just throw it in thinner without any cleaning that will happen.
I will use a 3 stage method- first wash gets most the gunk out, second a bit more, third I can either finish and dry or let soak ( for a short time) .
each stage can be about 1/4 cup for 1 brush..

I think cleaning oil is much easier than latex, just stinkier.

 

I've never seen a bottle of mineral spirits "turn" or go bad and I have had some sitting for decades. Unless some one stuck something in the container to clean it and that is what you are seeing.

 

Some here don't think I know what I'm talking about.
Bad news. I do ( not intended for you ..)

 

I for one have no doubt that you do.So do I.

 

CD- I hope that was a synth brush- if you used a natural bristle brush the water would make it bush out and be worthless.

 

The only thing that Kleen Strip Green strips is you of your green. It's worthless. I bought a gallon of it once and ended up throwing about three quarters of it away. You said it came out of the brush in globs, that tells me it's not a reducer, like true paint thinner. I'm going to take a chance and say that brush is not clean and once dry will harden up. If the heel hardens up the brush is then trash or good as a paint dust brush.

 

I should have known it wouldn't be any good as, in my experience, there aren't very many "green" cleaning products that do half the job of the products they are trying to replace. I'm sure there are exceptions.

Brushjockey, I just went to check on the brush. It's dried now and as you said, it did bush out. Bummer.

 

Agree, there are no decent "green" products when it comes to solvent alternatives.
At least you now have a good dust brush. Cut the handle off and it fits perfectly in the back pocket, handy for whenever you need to do some dusting when painting.