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Max Herrington
01-09-2001, 03:12 PM
Replacing deck on 26' motorboat with 5/8" plywood (not marine). Will applying Pentox preservative compromise the adhesive between the plys? Thanks.

Ian McColgin
01-09-2001, 03:24 PM
I'd only use CPES and then finish seal with a thicker epoxy before painting. The CPES will get way in there any you can believe Smith's warning on the lable that "This Product Cannot be Made Safe."

thechemist
01-10-2001, 01:04 PM
Is Pentox a name for pentachlorophenol? If so, do not put it anywhere where someone might sit on such treated wood, walk on it with bare feet, or inhale any vapors from treated interior wood. The stuff is a very effective preservative for wood, but has a toxicity profile that was not recognized in the early years when it was first put into the market.

Smacksman
01-10-2001, 05:36 PM
Surely, any preservative on ply will only go into the first veneer or the glue is not doing it's job properly.

thechemist
01-10-2001, 06:19 PM
Smacksman, You are correct......but in the real, modern, cut-any-corner-the-customer-might-not-notice world, as well as with old, weathered plywood, the glue line may lack integrity.

Not all plywood may be made with high-quality adhesives, such as resorcinol or MDI [methylene diphenyl diisocyanate] adhesives. Some may have the laminations glued together with crud, and some may be the interior grade crud mismarked or inported under false colors.

Somewhere recently I saw a post about someone recommending runing a plywood sample through a few automatic dishwasher cycles to verify its quality. Not a bad idea, really.....

Bruce Hooke
01-11-2001, 09:34 AM
I wouldn't worry too much about preservatives on the outside layer of plywood. My guess is that assuming the deck is kept reasonably painted the plywood will fail from rot starting in the internal voids in the inner plys long before the surface layer rots out. - Bruce

thechemist
01-11-2001, 02:21 PM
Yep....internal voids....inside condensation....water soaking in through plywood checks and cracked paint there......really better to use high-grade marine plywood insteand of cheap crud, but sometimes the pocketbook or material availability decides for us.

Dave Carnell
01-13-2001, 10:34 AM
Pentachlorphenol is an excellent wood preservative. It was banned from general sale because people were so sloppy with it, not because it was especially toxic. I have used it for over 50 years and bought a lifetime supply when it became obvious the EPA idiots were going to make it hardto get.

I just went on the web looking for a current MSDS sheet and all the references on allthe web and savvysearch were in German. My technical German is rusty after 60+ years, but as near as I good make out (in German) it is banned in the US in interior spaces and in contact with food and water.

Your deck after being painted will present absolutely no hazard.

Copper napthenate solutions in petroleum solvents are good and still readily avaible. Lowe's house brand looks like the lowest price per pound of copper.

CPES doesn't penetrate sound wood nor have any rot-preventing properties.

Smith's charlatanic claim that his products cannot be made safe is pure hokum. Go out in your shop and show me a can of anything that you would pick up and drink. Unless you hide your hootch behind the cans; then I'll join you. Splice the main brace.

Almost forgot; the penta won't bother the glueline of your plywood.

[This message has been edited by Dave Carnell (edited 01-13-2001).]

[This message has been edited by Dave Carnell (edited 01-13-2001).]

thechemist
01-13-2001, 12:06 PM
I wish to disagree with Mr. Carnell's absolute statement that you will have absolutely no health problems with a painted, pentachlorophenol-treated deck.

As concerns pentachlorophenol, I had occasion twenty years ago to speak personally to the wife of a man who treated the teak decks of their sailboat with penta. The wood was not painted and they spent considerable time on it in their bare feet. They both, in the immediate few years after beginning their cruising life on this boat, developed a variety of strange and severe health maladies. She was sure it had something to do with the chemicals, and he did not. He died of cancer in a few more years, she got rid of the boat and moved into a house. Her symptoms reduced and finally disappeared in a few years of this life, convincing her of the cause-and-effect relationship of state of health and pentachlorophenol exposure.

While only a single incident, and while the exposure levels were high, the results are consistent with various MSDS and EPA data for the material, I feel. I do not have to hand any safe exposure limits or threshholds for various cancers or other maladies.

Painted, the treated wood is not absolutely isoolated from you, but only relatively.

There are no absolute barriers.

None.

The paint [who knows what you will use: "Paint" is a generality. Latex? Enamel? Fancy polymer stuff?] will be permeable to some degree to penta. It is a small molecule, and can diffuse through paint films, more on hot days that warm the deck and soften the paint.

I promise you there will be SOME of that stuff that will get through your intact paint film. When it weathers, when the wood dries out a bit and checks with age, then the small cracks in the paint open up. You may not see them, but they will be there. Your exposure to the penta within the wood will increase. Mr Carnell may wish to add such risks to his life expectancy; consider well before you take such advice and make such risks your own.

Mr. Carnell seems to have some disagreement with Smith's label warning, judging by his statement, "Smith's charlatanic claim that his products cannot be made safe is pure hokum." While I have not the experience with Smith that Mr. Carnell apears to, I wish to point out that the offending statement is a quote from a particular product liability law of the state of California, cited on the label, namely Business and Professions Code Section 1714.45, if I read the fine print correctly. It would thus appear that there is some legal significance to the statement.


California has a legislative environment that is unique in many respects. It is likely that California requires, or at least gives a manufacturer the opportunity, to state clearly that unsafe things are unsafe, whereas in other states or countries one need not so clearly warn the user.

Wild Wassa
05-14-2003, 04:18 PM
Originally posted by thechemist:
"<snip> ... It is likely that California requires, or at least gives a manufacturer the opportunity, to state clearly that unsafe things are unsafe, whereas in other states or countries one need not so clearly warn the user."

I can't believe the detail on the packaging, of Smith and Co's CPES, compared to the Australian manufacturers. BoatCraft Pacific's safety warnings on their products, are totally minimal. Further on to house paint, the health and safety warnings are almost non exhistant, here in Australia.

There should be health warnings on a lot of timbers when they are purchased as well. Australian Red Cedar for example, is known to make some users very agressive. It has been banned by some institutions who teach furniture making. Even the humble turpentine has been banned by some art schools here in OZ.

There is an add on telly, that says, "there are 90,000 chemicals in used by society, less than 10% have been tested for effects on humans".

This figure for untested chemicals surprises me. I thought that testing, would have been mandatory or mandatory now days.

Warren.

[ 05-14-2003, 04:33 PM: Message edited by: Wild Wassa ]

Nicholas Carey
05-14-2003, 07:39 PM
Originally posted by Dave Carnell:
[Pentachlorphenol] was banned from general sale because people were so sloppy with it, not because it was especially toxic. I have used it for over 50 years and bought a lifetime supply when it became obvious the EPA idiots were going to make it hard to get.[ahem] Err...I have to disagree with the above statement. Here's a pretty cogent summary of the hazards associated with pentachlorophenol (http://www.fao.org/ag/agp/agpp/pesticid/pic/Download/DGDs/Penta.doc) (MS Word document) from the UN Food and Agriculture Organisation.

In essence, pentachlorophenol (PCP) contains a number of extremely long-lasting toxins, including dioxins and benzines.
Those of greatest concern are hexachlorodibenzo-p-dioxin (HxCDD), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the chlorinated dibenzofurans and hexachlorobenzene (HCB) (Royal Society of Chemistry, 1991; [iiPesticide Manual, 1991[/i]).In the short term, pentachlorophenol damages your liver and kidneys. "PCP is foetotoxic and teratogenic when administered during early gestation (Eisler, 1989)." Dioxins are a potent carcinogen; so are benzenes.

In the environment?
PCP is highly toxic to aquatic organisms. Invertebrates and fish are adversely affected by concentrations of PCP below 1 mg/l; algae are very sensitive to PCP.

Fish. PCP LC50: Bluegill 23-92.5 g/L., Rainbow trout 48-68.7 g/l.The above LC50 measures (Lethal Concentration, 50%) mean that 50% of the bluegill and rainbow trout population die when the concentration of PCP in the water is in the neighborhood of 50 parts per billion (do the math.)
Aquatic Invertebrates. Eisler (1989) reported a 48-hour median lethal concentration (LC50) of 260 g/l for the clawed toad.Clawed toads are a little tougher: it will take about 1/4 of 1 part per million to kill half the population.
Birds. Avian toxicity may be somewhat less sensitive to PCP than mammalian: LD50s 380 mg/kg bw for mallard duck and 504 mg/kg bw for ring-necked pheasantThe LD50 measurement (Lethal Dose, 50%) indicates the doseage at which 50% of the population dies. Mallards weigh in around 1250g, ring-necked pheasants weigh in at a little less, about 1100g. Does a bunch of these birds each with 475-500mg—less than 2/100th of an ounce—of PCP and you kill half of them.

Howard Sharp
05-14-2003, 11:31 PM
"California has a legislative environment that is unique in many respects. It is likely that California requires, or at least gives a manufacturer the opportunity, to state clearly that unsafe things are unsafe, whereas in other states or countries one need not so clearly warn the user."

The California warning labels have an interesting history. The law was the first of its kind to be enacted. Similar acts have been proposed in every other state in the US, but they have all been stopped by the chemical industries, which, after the California experience pooled a fund to stop any further legislation. The labels are based on solid science and warn of known dangers.

Most of what we know about chemicals comes from animal tests and epidemiological evidence, because it is illegal to test chemicals on people. The majority of chemicals have not been researched for their effects on adults or children, so even when a chemical doesn't have a warning label, it doesn't mean that it is safe. The CDC is starting to look in the most likely areas for toxic dangers to children, and I believe that the EU is moving to properly research all 30,000? chemicals in daily use. It could be that many chemicals which we think are safe will eventually be withdrawn.

In the meantime we can take note of those little California warning labels, and try to use less dangerous alternatives.

thechemist
05-15-2003, 01:24 PM
Originally posted by Howard Sharp:
"California has a legislative environment that is unique in many respects. It is likely that California requires, or at least gives a manufacturer the opportunity, to state clearly that unsafe things are unsafe, whereas in other states or countries one need not so clearly warn the user."

The California warning labels have an interesting history. The law was the first of its kind to be enacted. Similar acts have been proposed in every other state in the US, but they have all been stopped by the chemical industries, which, after the California experience pooled a fund to stop any further legislation. The labels are based on solid science and warn of known dangers.

<snip>Sadly, the science is not that solid.

Under California State Proposition 65, twenty or so years ago, anything detectable is considered equally hazardous. This was the lunacy of that rule, now a State law.

Merchants of oblong metal cans with soldered necks-and-handles have to warn the consumer that of the hazard of the lead; the steel manufacturers warn of the chromium in the can, the paper manufacturers may warn of formaldehyde in all paper products [at the parts-per-billion or trillion-level, but with modern technology almost anything becomes "detectable" regardless of actual hazard level] and prudent manufacturers cover their behinds and protect themselves from the proliferation of predatory plaintiff's lawyers with warnings to the consumer about anything and everything.

You know [adding another paragraph of ranting whilst editing to correct a typo], there's about fifteen thousand atoms of arsenic in every cell in the human body, I read somewhere [don't remember where...probably memory-loss due to aresnic]...it's a terribly common element. Under California's Proposition 65, we are all in violation, just being ourselves and walking our bodies down the street. Legally, we'd all have to have tattooed on our foreheads that our bodies contained detectable amounts of so-forth.

The State enforcement people "interpret" the law to mean only those things the manufacturer deliberately adds to the formulation, but that's not what the published law says. This leaves the door open for the lawyers.

Naturally, Industry will band together to defend itself. The consumer pays for the cost of extortionate or frivolous lawsuits with every product they buy.

The consumer has, I believe, become numb to hazard warnings since so many products appear with them.

Manufacturers themselves have a vested interest in not making excessively hazardous products, since their own production personnel may receive comparable or higher exposure than the consumer. Further, the bad press asssociated with a consumer's bad experience with a product hurts product sales, and manufacturers are in business to expand sales and create good product reputations.

As consumers, we will vote for the most user-friendly prodcts with our feet and our wallets, and that's how this free-enterprise system works.

Oh, and one more thing. Tin-plated cans of fruit cocktail or pineapple contain lead in the tin plate. Modern technology cannot separate them, and acidic foods dissolve the lead. Thus, those foods contain lead, usually in excess of the fifty parts-per-billion allowable under some-standard-or-other.

Since nothing can apparently be done about it, no one in the food industry or State government wants to talk about it.

Enjoy.

In reality, Life is nowhere-near-as-hazardous as the Merchants of Fear would have you believe. you really don't need rubber gloves to read the newspaper: It's only got a few parts-per-trillion of formaldehyde.

[ 05-15-2003, 05:24 PM: Message edited by: thechemist ]