Mineral Spirits or Paint Thinner

[Jim Rimmer]

This is a question about something I came to a conclusion about a few years ago and then began to doubt myself. Are mineral spirits and paint thinner the same thing? I think (thought) they are. In this month's FWW (Oct. 2009) there is an article about wipe on finishes and a sidebar about making your own. On page 54 there is caption that says "You can thin oil based brushing varnish with mineral spirits...". In the photograph it is very clear that he is using paint thinner.

Are they the same thing?

[george wilson]

Yes,they are.

[glenn bradley]

Paint thinner is made from mineral spirits and other 'stuff' (that's an industry term ). Mineral spirits is . . uh, er, mineral spirits(?).

This may help: http://www.paintquality.com/library/ingredients_3.htm

[Stephen Tashiro]

I've always been careful to use turpentine when directions called for turpentine, instead of using mineral spirits. Am I being silly?

Then there is the further distinction between "paint thinner" and "brush cleaner". I would be nice if some chemist would define the differences in all these products.

[Rich Engelhardt]

Hello,

Are they the same thing?

Most of the time - yes.

Mineral spirits can be called mineral spirits or paint thinner - on the label.

Paint thinner has to be labeled paint thinner on the label, it can't say it's mineral spirits. It can say it contains mineral spirits, but it can't say it is mineral spirits.

What is packaged as "Paint Thinner - contains mineral spirits", is usually washed or reclaimed solvent, or contains more than a trace of reclaimed solvents. It all came about years ago w/truth in advertising laws. I remember having to relabel skid after skid after skid of the stuff.( Bleh! Nasty, stinky, hot work.)

It's really kind of silly in some respects though. Quite often, the reclaimed/recycled/"Washed" material is of a higher quality than the virgin mineral spirits, due to the filtering & rerefining.

In case you ever wondered why the metal cans of Mineral Spirits on the shelf of the borg are a couple of bucks more than the plastic containers in the big display labeled "Paint Thinner" - that's why.

Stephen,

I've always been careful to use turpentine when directions called for turpentine, instead of using mineral spirits. Am I being silly?

Not really.
Turps are made from pine sap & pure gum spirits of turps are sharper (stronger) than mineral spirits. Turps also slows down the dry of materials - makes it easier to brush and reduces drag - more than mineral spirits.
If the label says use turpentine or mineral spirits to thin, always go with turps.
For cleanup, always go with mineral spirits (or paint thinner it that's what's on the can). Turps will gum up brushes if used for cleanup.

Then there is the further distinction between "paint thinner" and "brush cleaner".

"Brush Cleaner" is an emulisifier. A strong detergent of sorts, similar in function to D&L Hand Cleaner. It turns the solvent based material into a water souluble solution. Usually it has a picture on the label of the container of a brush being rinsed under a faucet or big bold lettering that touts water cleanup.

[Stephen Edwards]

I wonder if there are different grades (quality) of mineral spirits. Around here at the local lumber/hardware store they have gallon metal cans of something called Paint Thinner. On the can it says: contains 100% mineral spirits. It lists no other ingredients.

For about $4.00 more they have a plastic gallon jug that's labeled Mineral Spirits. On the jug it also says 100% mineral spirits. The stuff in the plastic gallon jug is a better product for cleaning brushes, etc.

I never have understood that, either.

[Peter Quinn]

I've always been careful to use turpentine when directions called for turpentine, instead of using mineral spirits. Am I being silly?

Then there is the further distinction between "paint thinner" and "brush cleaner". I would be nice if some chemist would define the differences in all these products.

I'm no chemist, but the RAPID BRUSH CLEANER I buy is definitely NOT 100% mineral spirits, there seems to be a fair quantity of Naphtha in there. Sure is volatile whatever it is, and it cleans way faster and more thoroughly than miniral spirits.

[Myk Rian]

Rich;
Thanks for the info. Good stuff.

[Cliff Rohrabacher]

For about $4.00 more they have a plastic gallon jug that's labeled Mineral Spirits. On the jug it also says 100% mineral spirits. The stuff in the plastic gallon jug [..]

I tend to wonder about the ability of the poly jugs to effectively prevent slow transpiration of the solvent through the polymer.

[Stephen Tashiro]

Turpentine definitely dissolves the average plastic container within a few days.

[george wilson]

Turpentine SLOWS down drying of materials,and REDUCES brush drag? Haven't you got that exactly backwards?

For many years when I was making instruments in public in Williamsburg,we finished varnished instruments by brush. Mineral spirits made the varnish brush on so smoothly that it looked as if it had been sprayed on. We got very good at it.

Turpentine is full of oxygen,and made the varnish drag due to accelerated drying.

There are different products labeled as turpentine,and the real stuff was usually labled"from the living pine". It is hard to find,and was even in the 70's. The other stuff is much more common,and smells different. it is distilled from ground up stumps,and is not the real stuff. If you have had much experience with turpentine,you can smell the difference.

I used to make violin varnish from terpene resins,which is made from bubbling air through real turpentine(turps from now on). It would get thicker and thicker,and be as clear as a diamond. You could take this very thick turps and simmer it until the volatile parts evaporated off,leaving a crystalline resin in the pan. This is terpene resin. It was then mixed and simmered with polymerized edible linseed oil until gossamer strands would come away from the mass when a cool surface was touched to it,and pulled away. I got into using edible linseed oil because it is perfectly clear,and not mixed with driers,etc.. It will not dry unless first heated until it turns a deep golden color,which shows it is polymerized. If cooked in the presence of iron,I could make nice,permanent transparent brown varnish. When allowed to cool to a warm temperature,I added turps to thin the varnish.

REAL TURPS is dangerous. It was discontinued by our paint shop years ago because if gotten on the hands,over the years it caused arthritis. It is very bad to breathe.

Mineral spirits is better to use as it isn't as harmful,and the paint or varnish goes on much more smoothly.

Making varnish is dangerous,and should NEVER be attempted except out doors,and only in small quantities,like a pint. I had several big fireballs go off over the years.

This idiot in Williamsburg wanted to make varnish. I warned him to only ever do it out doors. Of course he ignored 15 years of experience,and nearly burned down a historic building.

[David Keller NC]

I wonder if there are different grades (quality) of mineral spirits. Around here at the local lumber/hardware store they have gallon metal cans of something called Paint Thinner. On the can it says: contains 100% mineral spirits. It lists no other ingredients.

For about $4.00 more they have a plastic gallon jug that's labeled Mineral Spirits. On the jug it also says 100% mineral spirits. The stuff in the plastic gallon jug is a better product for cleaning brushes, etc.

I never have understood that, either.

The reason has to do with the analytical requirements for calling something "mineral spirits" vs. "paint thinner". Regardless of the composition, the "mineral spirits" label is more strict, and therefore costs more to produce.

BTW - "brush cleaner" is a mixture that includes the constituents of Laquer Thinner. Laquer thinner is in some ways similar to mineral spirits as its composed of aliphatic alkanes (i.e., not aromatic compounds like toluene). Obviously, however, laquer thinner is composed of compounds with much lower boiling points than mineral spirits.

This is one good way to restore a high-quality paint brush that's been used with latex where the painter did not stop to clean the brush out every 30 minutes or so. It works well on removing semi-hardened latex, but not so well on really well-cured paint.

[John Lohmann]

This is just a stupid story from my past about turpentine & plastic. I had a hot wheels car in 1968? A silhouette it was painted purple & it was cool. I saw some gloss black spray paint in the garage & thought this would look great black. It didn't. Being 8 or so I put it in a jar full of turpentine, went to school, the next day I pulled it out of the jar, & guess what? No tires no interior & no coupe windows. That's how I know to test everything for compatibility before you use it.
I miss my hot wheels,
John

[george wilson]

Do I hear a teeny little bugle playing taps?

[John Lohmann]

A little green Army man playing taps before he gets melted by a magnifying glass