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Lead tests reliable?

Posted by morgan88 (My Page) on
Mon, Oct 22, 12 at 18:05

My house was built in 1923. The woodwork is covered in several layers of horrible paint. Green, blue, yellow, white, white, and white. The top layer is peeling off. My guess is the previous owners slapdashed latex paint over oil? Without any kind of primer.
Anyway, I have chipped away at the layers and have tried 2 different a lead tests several times and all came up negative. Everyone and their uncle says I have lead paint. People who come to work in the house almost go out of their way to inform me of this and so I buy more tests. All negative.
Is it possible there is no lead paint in this 1923 house? I have kids and need


Follow-Up Postings:

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RE: Lead tests reliable?

check google for lead paint testers in your'e state, that way it is documented if you do or don't


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RE: Lead tests reliable?

The professional labs have access to equipment you don't, like mass spectrophotometers.

The DIY test kits can have a lot of false negatives and positives because they are chemistry-based and some samples don't let the lead (if any) react.

It's also possible that your woodwork was unpainted for long enough that all that tacky paint is lead-free.


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RE: Lead tests reliable?

"mass spectrophotometers."

An X-ray fluorescence tester is the typical field tool used.

The lead in the paint releases specific photons when excited by x-rays or gamma rays.
The photons are detected and used to determine the concentration of lead present.

The chemical testers work adequately for gross screening, but you have to insure that every layer of paint is touched by the chemical and observed for the color change in the reagent.

It can be hard to see the color change against some background colors of paint.


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RE: Lead tests reliable?

Thanks for the info.

I would be fine with leaving it alone, painting over it all and getting on with my life, but the previous owner did one horrible job and its peeling off, it's literally just falling off everywhere. I've never seen such a thing. I can't paint over that.

I guess my next step will be the professionals.


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RE: Lead tests reliable?

If you aren't wanting to go back to original wood, then just remove the top layer which is peeling using chemical remover. If the layers under that are adhering fine, then just coat with a new coat of primer and paint.

So long as there are no loose flaking paint chips or dust, and you don't let your kids chew on the woodwork, removing the peeling layer and repainting is fine.


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RE: Lead tests reliable?

If you aren't wanting to go back to original wood, then just remove the top layer which is peeling using chemical remover.

How are you going to avoid the chemical remover removing more than the top layer?


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RE: Lead tests reliable?

I have encountered that problem. There is an out of the way area I have been experimenting with. I use duct tape to help peel off the top layer. This gets rid of about 60% of that top layer. Of course the rest sticks. I used some citri strip I already had and that is slow going but easy and that goes through other layers.


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RE: Lead tests reliable?

Another way to break the bond betwen paint layers is using a steamer. It's particularly useful at the latex over oil juncture. But there's a caveat: you may just need to remove the outermost layer, but there's no telling exactly where the steam will "decide" the weakest layer is, it could be much deeper than you wish, or need, to go.
Also: once the paint is loose it will be very brittle so you will have an issue collecting all the little scraps before they get crushed down into dust that can float or get tracked around your house. So if you are removing what you suspect may be lead paint, use appropriate lead-safety precautions. Be sure to seal off the rooms; wear lead-room only clothes and shoes; and meticulously collect and clean up the areas after removal. I'd use plastic drop cloths so you can just toss 'em. (Check local regs for disposal of drop cloths and lead paint detritus.) Wash the lead room clothes in separate loads afterward and run a cycle (or so) empty afterward to avoid transferring lead particles to other clothes. And whatever you do do not use your vac to clean up the mess.

I second the usefulness of sticky tape for removing loose, crumbly layers en bloc, except I don't use duct tape, but rather clear, wide, really sticky packing tape. I smooth it on very firmly, sometimes going over it with a tool to press on it. Then off it comes, often leaving nothing behind or even generating much loose dust. It's a little like leg waxing.

L.


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RE: Lead tests reliable?

Please have your children and selves immediately tested for lead excess via a simple blood test! Some labs may suggest hair or nail clippings too.

Send your multiple paint scraps off to your state lab after you call them first and get the address to their lead testing department or state handpicked lab. Each state has an office specific for lead paint issues.

Something doesn't sound right given the age of the house and layers of paint you are taking off. I agree with the PP to immediately secure the areas you have worked in with plastic from the rest of the house. You might want to have a lead paint abatement crew come in and clean up. This could be a very serious situation medically. Cleaning off the potential dust from your bodies, hair, nail-beds can be done with advice, with clothes and shoes replaced with new until with 100% certainty lead paints presence or absence is determined.

Here is an abstract on the most popular home lead check test which shows a high falsely negative test percentage. Take care and resolve this issue definitively.

"There has been a long-standing need for a technique that can provide fast, accurate and precise results regarding the presence of hazardous levels of lead in settled house dust. Several home testing kits are now available. One kit manufactured by Hybrivet (LeadCheck Swabs) is advertised as able to detect lead dust levels that exceed the U.S. Environmental Protection Agency’s dust lead standard for floors (40 μg/ft2). The purpose of the study was to determine the ability of LeadCheck Swabs to instantly detect lead in dust above EPA’s hazard standard. A trained risk assessor collected two hundred LeadCheck Swab samples side-by-side with standard dust wipe samples. The result of the LeadCheck Swab (positive (pink or red) or negative (yellow to brown)) was compared with the laboratory results for the corresponding dust wipe (over or under 40 μg/ft2). The LeadCheck Swabs produced a false negative rate of 64% (95% confidence interval: 55%, 72%). The likelihood of a swab producing a false negative depended on substrate (painted or non-painted) and surface type (floor or sill). Changing the interpretation rule by classifying all swab colors except yellow as positive yielded lower false negative rates under some test conditions, but still produced high error rates. LeadCheck Swabs do not reliably detect levels of lead in dust above 40 μg/ft2 using published methods under field conditions. Further research into alternate methodologies and interpretation guidance is needed to determine whether the swabs can be appropriately used by consumers and others to test homes for lead dust hazards."

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2170477/


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RE: Lead tests reliable?

Better is the enemy of good enough.


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RE: Lead tests reliable?

^^Admiral of the Fleet of the Soviet Union, Sergey Georgiyevich Gorshkov, (February 26, 1910 - May 13, 1988).

"Лучшее - враг хорошего": it was said to have hung in his office.


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RE: Lead tests reliable?

It is also commonly referenced as "Perfect is the enemy of good" and attributed to Voltaire.

It has a very long history in numerous projects.


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RE: Lead tests reliable?

Chances are really good that your painted trim has lead paint. The only way you'll be sure is by spectrometer. If you can't afford it (see below for what it cost me), then try some detective work: Are you able to get an approx idea of how many layers of paint? If the woodwork was bare and painted over in the 80s, then maybe you don't have a lead paint issue. Look at the # of owners the house has had and then just guesstimate how many times it could have been painted. Most people don't repaint frequently. Usually on moving in, if that, and then...what do other people think?--Every 10 yrs? Maybe never?

Like you, we have children to worry about. We had our house professionally tested using a spectrometer when we moved in--all of our painted trim had lead paint. The painted plaster walls had a very tiny % of lead. For a large house, getting all the rm walls, the trim, exterior walls, and a small soil sampling cost ~ 1.2k. It was expensive. But I know exactly how much lead is in each area and can balance the risks of my renovation work. What I don't know is which paint layer contains the lead. The spectrometer does not analyze layer by layer. They just hold it up to the paint and get a total lead reading.

I know a lot of people recommend just painting over when you're dealing w/ a health hazard like lead paint and children, but in our house, if we were to paint over everything we'd risk having more paint flake off eventually--the thick layers of paint on the interior trim have become brittle w age and are prone to chipping off. Another layer of paint is just going to make the problem worse. It's hard, I feel your pain! I'm doing a combination of some stripping and some repainting, depending on the area. I only do paint removal when my daughter is out of the house and I can contain the area. Then I only wet sand, vacuum frequently, wet wipe all areas where I'm working. I also wash the clothes I've used by themselves and sometimes wear disposable coveralls. The phosphate in TSP is supposed to bind w/ lead, so can be useful for clean-up, but it can also hurt finishes. We're also getting lead paint screening. Not yearly, but often enough. No probs so far.

This is my opinion and completely anecdotal, but based on what I've read (and I've read extensively), most of the lead paint health issues are based on serious airborne dust, water from lead pipes, or pollution. One of my friends who recently interviewed at MIT and is incredibly bright used to chew on lead fishing weights when he was a kid...go figure. So, I suppose my message is: be safe, but not hysterical. :)


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