Deck stain improvement experiment

This follows the threads "recipe to restore VOCs?" and "more on paint/ stain VOCs." It's my experiment on "doctoring" deck stain to get better performance. This is Episode 1.

I bought a pint of Klean-Strip boiled linseed oil (BLO) and a gallon of Klean-Strip 100% mineral spirits paint thinner, and intend to use them to modify my new reformulated retail oil-based semi-transparent deck stain in the hope of improving its durability and water resistance. Because I'm adding linseed oil, I'll also add some mildewcide.

The BLO says ZERO VOCs on the label and in its MSDS (online), which presumably means no solvents added. There is no info on the label or in its MSDS about ANY additives, like metal salts, and the MSDS lists no concerns of carcinogens. (Other manufacturers' MSDS sheets list things like cobalt as a hazard...) I HOPE there's something added to speed up drying... It's somewhat thicker and more yellow than cooking corn oil.

If VOCs were the only concern, it would appear that anyone, anywhere, is perfectly free to add as much zero-VOC BLO as they like to any oil- based stain or paint, assuming chemical compatibility, without violating ANY VOC regs. But there's more.

I assume that there are good reasons to add a solvent as well as the BLO to my deck stain, since just about every recipe I've seen for other applications uses both. Maybe it improves penetration. I assume that lower VOCs were obtained primarily by reducing or replacing the old solvents in paints and stains, which may account for the poor performance. So I figure I'll restore 'em.

The mineral spirits label says 791 g/l VOCs, while its MSDS says 815 g/ l VOCs. I don't quite know how to reconcile this; maybe I got an old one... The MSDS bulk density of this product is 6.380 lb/gal. Multiplying that by 120 gets 765.6 g/l, which is LESS than either listed VOC content! I can't resolve that one, either. (That conversion factor should really be 119.83, but everyone uses 120...) Any way you do it, though, it's 100% VOCs.

The questions remain: how much shall I add, and in what proportions, to a gallon? And can I do it without violating the VOC regs? (I really don't care about the latter, but I'll play the game...)

I have several cans of stains, some new and some old. The VOC numbers range from 250 to 610 g/l. I will assume that it will be perfectly legal to add stuff as long as I don't exceed the original VOC number on any given can. So how do I do that? Easy. All I have to do is mix the BLO and mineral spirits separately in a proportion that produces a mix with a net VOC content less than or equal to that number. Then, no matter how much of it I add to the stain, the original VOC density will not be exceeded.

Let's say the stain label says 350 g/l VOC. I have BLO at 0.0 g/l VOC and mineral spirits (MS) at 791 g/l VOC. Let f be the fraction of BLO, and (1-f) the fraction of MS. The proportions to match this number are found from:

350 = f * 0.0 + (1 - f) * 791

which reduces to f = 0.558 BLO, (1 - f) = 0.442 MS. Since the MS is the VOC source, that 0.442 is the MAXIMUM fraction of MS allowed. So I could use anywhere between 0.0% and 44.2% MS, with 55.8% to 100% BLO, as long as the sum was 100%. To make things simple, I'd probably go to a 40% - 60% mix, or 2 parts MS to 3 parts BLO, as the max.

If that number were 100 g/l VOC, as has apparently become the limit in southern California, the result would be only 12.6% MS as the max, with 87.4% BLO, or a ratio of 1 part MS to 7 parts BLO.

So now I have a guideline for satisfying the VOC regs. The next questions are: Is the mix compatible with the new formulations? Do I want the MAX MS mix, or something less? And then, how much of the mix shall I add to a gallon of stain? More to come.

Reply to
jlfork
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Use Cabots, it works for alot of folks

Reply to
ransley

I can answer the MSDS question as I write a lot of them. Most likely the technical/marketing folks did not tell the MSDS writer that they had a new VOC number. The MSDS should still be good for the intended users of the material if it satisfies OSHA's HAZCOM requirement.

As for you becoming a paint chemist - you are terminally stupid ;(

Reply to
Frank

Maybe next time, Mark. I have new cans of stain left over from last year, so I'm going to experiment with them. What better comparison could there be than the same deck with the same stain, one version original and the other doctored up?

Reply to
jlfork

On Sep 19, 10:01=EF=BF=BDam, Frank wrote= :

Why, thank you, Frank, for your comments. What a helpful fellow. I don't need to be a chemist to determine proportions. I'll find out soon enough if it's compatible. What the hell do you care? It's my deck, my stain, my money, my labor, and I'm not violating ANYBODY'S regs. If it fails, I'll sand it off and go with the conventional approach (i.e., a better stain). If it succeeds, you can bet I'll let everyone know about it. I'll report on it every once in a while. First will be after it's mixed, applied, and allowed to dry. Assuming that goes okay, it'll be every 6 months or so. If it fails, I'll report that, too.

Reply to
jlfork

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