I'm a UK based sash window restorer - often restoring and repainting Georgian or Victorian windows which will have many layers of lead based paints.
Such historic paint is mostly scraped off (non-hazardous) but sanding is inevitable (hazardous). I've been monitoring the lead in my blood and continue to think about not only the best behaviours to adopt (to protect my health from dust inhalation) - the most meaningful side of the challenge imo - but also which equipment is best to assist in that effort. I've a couple of Festool CTL Midi 1s which are used both in customer's homes (when restoring the sash box), but also in my workshop where the sashes themselves are worked on. I didn't go for CTMs (over CTLs) as the additional alarm (I felt) was only really necessary for those that don't have good routines and check the bags and are alert to blockages etc. Rightly or wrongly I didn't feel I was in that category.
For what follows: I may have got some things wrong. I'm not an expert but I consider myself to be more informed than most. So, if you know that for sure that any of the following is incorrect (and haven't just been served up some data by ChatGPT et al) then do inform this thread, otherwise I'd be grateful if you didn't as this topic is complicated enough without misinformation being added.
Lead paint dust (or fume) is deemed to be carcinogenic and, in terms of particle size I believe it's between 0.1-0.7 microns. That means that "some" lead dust can be categorised as MPPS (most penetrating particle size) which is deemed to be at between 0.1-0.3 microns (and smaller). I believe HEPA filters fall into two categories (and of course standards and naming conventions aren't the same between the US and EU/UK) but from what I understand H13 is a 'True' HEPA which should capture 99.970% of mpps and H14 'Highest Medical grade' HEPA (EN1822) should capture 99.995% of mpps. H14 are said to have a ten fold improvement in particle retention. So the difference, when it comes to mpps would appear to be pretty meaningful.
The filters used in CTL & CTMs are the same 'HF-CT comp' and those used in the CTH are referred to as 'HF-CT'. I believe the former is H13 standard HEPA ("Festool has exhaustively tested its CT Dust Extractors to the strictest standards (IES RP-CC-002, IES-RP-CC-0034.1) to ensure that our units not only filter particles to 0.3 microns with 99.97% efficiency"). I'm not sure where the latter is H14 grade or not, I'm guessing it's also H13 (but would like that confirmed).
Festool extractors all send their collected dust to the bag and the air then passes through the HEPA filter before it's returned to the room. HEPA filters don't work just like a sieve or water filters per se. Particles >0.3 microns (non-mpps) are more easily trapped. Their greater inertia prevents them from navigating the filter's winding fibers, causing them to collide and stick to the filter fibres (interception). Mpps collide with gas molecules (known as Brownian motion or diffusion) and become trapped by the filter fibres. It seems therefore that the filter in the Festool extractors is all important when it comes to mpps and H Class (which i defined by the UK's HSE as the required equipment when working with hazardous dust).
Festool no longer sell their H Class extractors (discontinued in the UK, not sure about the US) but you can still get the 578558 CTH Midi 1 and the 577866 CTH 26 EI from agents. However, I don't believe the filters they used in them are H14 (99.995%). Can anyone confirm?
Such historic paint is mostly scraped off (non-hazardous) but sanding is inevitable (hazardous). I've been monitoring the lead in my blood and continue to think about not only the best behaviours to adopt (to protect my health from dust inhalation) - the most meaningful side of the challenge imo - but also which equipment is best to assist in that effort. I've a couple of Festool CTL Midi 1s which are used both in customer's homes (when restoring the sash box), but also in my workshop where the sashes themselves are worked on. I didn't go for CTMs (over CTLs) as the additional alarm (I felt) was only really necessary for those that don't have good routines and check the bags and are alert to blockages etc. Rightly or wrongly I didn't feel I was in that category.
For what follows: I may have got some things wrong. I'm not an expert but I consider myself to be more informed than most. So, if you know that for sure that any of the following is incorrect (and haven't just been served up some data by ChatGPT et al) then do inform this thread, otherwise I'd be grateful if you didn't as this topic is complicated enough without misinformation being added.
Lead paint dust (or fume) is deemed to be carcinogenic and, in terms of particle size I believe it's between 0.1-0.7 microns. That means that "some" lead dust can be categorised as MPPS (most penetrating particle size) which is deemed to be at between 0.1-0.3 microns (and smaller). I believe HEPA filters fall into two categories (and of course standards and naming conventions aren't the same between the US and EU/UK) but from what I understand H13 is a 'True' HEPA which should capture 99.970% of mpps and H14 'Highest Medical grade' HEPA (EN1822) should capture 99.995% of mpps. H14 are said to have a ten fold improvement in particle retention. So the difference, when it comes to mpps would appear to be pretty meaningful.
The filters used in CTL & CTMs are the same 'HF-CT comp' and those used in the CTH are referred to as 'HF-CT'. I believe the former is H13 standard HEPA ("Festool has exhaustively tested its CT Dust Extractors to the strictest standards (IES RP-CC-002, IES-RP-CC-0034.1) to ensure that our units not only filter particles to 0.3 microns with 99.97% efficiency"). I'm not sure where the latter is H14 grade or not, I'm guessing it's also H13 (but would like that confirmed).
Festool extractors all send their collected dust to the bag and the air then passes through the HEPA filter before it's returned to the room. HEPA filters don't work just like a sieve or water filters per se. Particles >0.3 microns (non-mpps) are more easily trapped. Their greater inertia prevents them from navigating the filter's winding fibers, causing them to collide and stick to the filter fibres (interception). Mpps collide with gas molecules (known as Brownian motion or diffusion) and become trapped by the filter fibres. It seems therefore that the filter in the Festool extractors is all important when it comes to mpps and H Class (which i defined by the UK's HSE as the required equipment when working with hazardous dust).
Festool no longer sell their H Class extractors (discontinued in the UK, not sure about the US) but you can still get the 578558 CTH Midi 1 and the 577866 CTH 26 EI from agents. However, I don't believe the filters they used in them are H14 (99.995%). Can anyone confirm?
