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How do chemical tests stack up against XRF for surface lead detection of paint?

Updated: Mar 24

How do chemical tests stack up against XRF?

to find out I did a little study where i produced several paint samples. These paint samples by mixing some lead based paint into modern house paint.


It was eggshell finish, indoor paint and after homogenizing them to the best of my ability. I put a general uniform thickness onto each square that had been taped off on this piece of sheet rock.



I allowed it to dry for four days and then I tested each one with a variety of chemical tests as well as the XRF.


Both methods successfully detected the lead in each of the boxes. The first box was the only one where the lead content was too low to detect with the chemicals but was detected at a range of about 120 parts per million lead by the XRF unit.


While this would be too high to sell in the U.S today as the limit is 90 parts per million, the limit set by the CSPC in 1973 was 600 and that persisted until 2008 when they lowered it to 90

I tested all the boxes with the sodium rhodizonate based swabs that I invented in 2019

I currently sell those on Amazon and they have detected lead on millions of surfaces so far conversely, there's a new type of test out which relies on fluorescence this one is a bit more tricky and I am always still tweaking the mixture to ensure the highest degree of sensitivity.

Both of these swabs would not meet current EPA regulations ironically because they detect lead far below the quote on quote limit of 5,000 parts per million.


The real area where XRF outshines the chemical tests is when the lead is over painted


Now while this does not, over painted lead does not cause an immediate threat to the occupants, if it's disturbed without being properly investigated it certainly will.


So if you're going to renovate always adhere to the rules surrounding the RRP rule. Renovation of over six square feet inside of a house necessitates inspection by a qualified person and if you use a professional contractor they should either have RRP certification themselves or know where you can get a professional lead inspection to determine if you they need to comply with the laws when they renovate this is a huge area where people wind up getting poisoned because they don't know that there's lead in the walls and they do a lot of renovating to buried lead so even though the 3M swabs which are currently unavailable are able to rule out the presence of lead paint I think that this rule is a little bit misguided since over painted lead would not qualify as a net positive result and therefore the people would have a false sense of security.


Below you can see me testing all the paint boxes with the swabs.



Although i do enjoy using chemical tests more, and they are faster and more accessible to the average person.


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