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Discussion Starter · #1 ·
I've always thought that whatever was used for clean up is what's used for thinning but I've seen on a can where acetone is listed for thinning. I've read where some still use mineral spirits anyways. Any comments?

P.S. Just the slightest amount of acetone in the air and it's instant headache for me! :vs_no_no_no:
 

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Uh, acetone is the only VOC compliant solvent readily available in stores that can legally be added to oil based paint. Adding mineral spirits violates the VOC regulations. Mineral spirits will work fine and won't adversely speed up the drying time but you may draw the ire of the VOC black-suit dudes. Actually there is no regulations for what the end user uses as long as it is used by a diy'er on their own property and not for an item for resale. The solvent listed on the can is the only solvent that can be used without raising the "as sold" voc level, as per voc regulations. The paint companies cannot recommend any additive that raises the voc content of the paint. So they resort to listing acetone which would be hell to use when brushing it.
 

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Discussion Starter · #7 ·
Uh, acetone is the only VOC compliant solvent readily available in stores that can legally be added to oil based paint. Adding mineral spirits violates the VOC regulations. Mineral spirits will work fine and won't adversely speed up the drying time but you may draw the ire of the VOC black-suit dudes. Actually there is no regulations for what the end user uses as long as it is used by a diy'er on their own property and not for an item for resale. The solvent listed on the can is the only solvent that can be used without raising the "as sold" voc level, as per voc regulations. The paint companies cannot recommend any additive that raises the voc content of the paint. So they resort to listing acetone which would be hell to use when brushing it.
So they will never stated mineral spirits or like some, nothing at all?

I use a respirator when I spray anything. I'd use a organic filter for the acetone if I go that route.

In the car restoration forums, they claim mineral spirits dry too slow. I think they were saying that one or the other reduces sheen.
 

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Rustoleum oil based paint.
I'm pretty certain Rustoleum's Oil Base Enamels may be thinned with regular Mineral Spirits - though, I would contact Rustoleum first to confirm. The primary solvent in Rustoleum Rust Stop is Mineral Spirits, and in the Professional line the primary is Aliphatic Hydrocarbons...in both cases, straight Mineral Spirits falls into the primary...VM&P Naptha may also be a suitable reducer.

The reason they recommend thinning with Acetone is to allow for reduction without compromising the VOC output of the host product (Acetone is an "exempt" solvent and therefore = 0 VOC). A manufacturer cannot recommend reducing with a solvent that will knock the product out of VOC compliancy.

I don't like to reduce oil/alkyds with acetone, even though they are compatible. Even though the evaporation rate is very fast, it will NOT accelerate the drying time of an alkyd product - and in many instances, it will actually slow the "dry-through" time, the time for re-coat and the cure "hard" time. DO NOT SUBSTITUTE LACQUER THINNER FOR ACETONE...especially with alkyds. The reasons are many, but the primary issue is the long-term, destructive affect lacquer thinner poses to an oil/alkyd resin...and Rustoleum even specifically mentions not to thin with lacquer thinner.

In this age of VOC's, both awareness and compliancy, it is necessary to understand that solvent chemistries in paint aren't what they once were. To keep oil products VOC compliant (for now, at least), manufacturers are working with some odd combinations of solvent and resin blends to achieve a market-demanded, but compliant, oil based coating. The solvent structure is no longer nothing but petroleum distillates - but now include plant based and engineered solvents, with blends of alcohols and ketones. Not all of these solvents play well together. The same is true for developed resin blends - and the reaction between. This may be why many oil/alkyd products may dry differently than they once did - why they no longer "wet" a surface as they once did - why they smell different (and usually worse) - why a wet-edge isn't as easy to sustain as it once was with alkyds - why, now more than ever, applied thickness and re-coat times are so critical to the proper dry and performance of an alkyd...and on & on & on... I know of one "standard" oil-based product on the market (an agricultural product) that, due to the solvent blend used to stay compliant, mineral spirits may not be used to thin with. Not only because of the VOC (compliancy) issue, but also because the solvent blend (which is largely petro-distillates) will not blend with the safe and mild aliphatic solvents because the film will wrinkle like a raisin if done so, even in small amounts ( I often times reduce this product with MS, then conduct a drawdown just to show the consequence of not following package directions...the drawdown applies like you'd expect, then slowly begins to wrinkle throughout the entire film like a cheap special effect in a low budget sci-fi film)...(now you see why I'm not invited to all that many parties).

Anyway, again I'd probably feel comfortable thinning with Mineral Spirits, but I'd like to hear Rustoleum say, aside from the VOC thing, it's OK to do so. Peace.
 

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Why are you guys using xylene instead?

I asked Rustoleum about using mineral spirits to thin.
Ayuh,.... I read it somewhere along time ago, before the internet, 'n it Worked,....

Ain't seen any reason to change my thinkin',.....

'course, I don't keep up with the latest jibber-jabber from faceless bureaucrats in Washington either,...
 

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I think if this is an alkyd product that you're applying by brush or roller sleeve, then you'd be fine thinning it with mineral spirits.

If you're going to spray this Rustoleum paint, you might want a thinner that evaporates faster so that you can spray on a thicker coat without it sagging on you.

Here's my understanding of the fastest to slowest evaporating solvents that can be used as thinners for alkyd paint:

FASTEST
1. Acetone
2. Toluene
3. Lacquer thinner (which is typically mostly toluene)
4. Xylene
5. Methy Ethyl Ketone (MEK)
6. Mineral Spirits
7. I don't see why it wouldn't be possible to use glycerine as a thinner for alkyd paint.
SLOWEST

And, the above list doesn't include denatured alcohol or methyl hydrate, and I don't see why you couldn't use those as thinners for alkyd paint either.

The only way I see that using acetone as a thinner for alkyd paint makes sense is if you're spraying it, in which case you want the thinner to evaporate rapidly so that your paint doesn't "run" on vertical surfaces.

I'd phone some body shops and see if they've ever used isopropyl alcohol for thinning alkyd spray paint. I've got next to no experience with spray painting, but I'd be willing to try thinning alkyd paint with isopropyl alcohol instead of acetone. I don't see why ANY rapidly evaporating solvent wouldn't work as well as acetone.
 

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Don't quote me on this, but I believe that prior to the most recent VOC reformulations, that Rustoleums recommended reducer for their Stop Rust (and probably Professional series) was Xylene. And I'm playing a little mind trivia with myself here, but I seem to remember many rust-inhibitive lines of enamel from other manufacturers often suggested Xylene as the preferred reducer...

You asked "why?" ...and the reasons may be many-fold. Speaking generally, rust-inhibitive enamels are very tough & durable, hard-drying alkyds. Designated for interior & exterior use, they must be able to provide corrosion resistance to surfaces exposed to weather and the most damaging of all elements (sunlight), and still be able to withstand frequent handling, abrasion, impact, grinding, etc. The tougher the resin, the more difficult it may be to dilute with common mineral spirits - thus the need for a recommendation like Xylene. Xylene is a medium strength aromatic solvent, but greater in strength than mineral spirits. As it relates to paint, all solvents will serve as either a "solvent" (dissolves) or "diluent" (dilutes) - unless you're using a non-reactive resin, such as shellac or some lacquers (and others) - your recommended reducer must be able to dilute, without dissolving. Some alkyd resins can't be diluted, thoroughly or completely, with mineral spirits, and need the stronger Xylene as a diluent. Other alkyd resins (interior only products, or perhaps less durable "rust inhibitive" enamels) may be too sensitive to xylene (which may serve as a "solvent" and dissolve the resin) and be better reduced with mineral spirits which dilutes the resin (and dissolves nothing).

It's because of this that it is so necessary to follow manufacturer's directions when reducing a product for spray, or general application. Stronger solvents will absolutely "thin" a product for application, but could dissolve the resin - in that scenario, you may have a dried film that is incapable of providing the type of protection you were expecting....or paid for. Just because it "works" doesn't mean it's the best thing for reducing your product with. If that was the case, just use gasoline to reduce with - it's cheaper and more potent even than Xylene (I'm kidding - don't use gasoline). None of this is to say that an oil/alkyd product, that recommends mineral spirits as a reducer, is a lesser quality than one that recommend Xylene. No determination can be made to the quality simply based on the recommended reducer...

Another reason Xylene may be preferred to mineral spirits is that Xylene may displace moisture than mineral spirits - and be better at delivering the protective paint (or primer) deep into the contours of the surface, minimizing the risk of flash rusting during app or drying. Xylene may also be more tolerant of surface oils or grease at time of application than mineral spirits (don't test this - clean the surface of all oils and grease prior to painting).

Contrary to those advantages, Xylene has a stronger odor than mineral spirits, and in some instances, Xylene may attack solvent sensitive coatings if applied in a repaint situation...

So...there you go. What did Rustoleum say about using mineral spirits?
 
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