Homebrew PCBs

> -----Original Message-----
> From: derekhawkins [mailto:eldata@...]
> Sent: 26 September 2006 10:05
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Re: UV Light Sources
> 
> 
> >FYI in the English language we spell "vapor" as vapour, so a search 
> >missed it
> 
> Missed what? Searching on >mercury vapour< gives another set of hits 
> including this;
> 
> >>DO NOT break the outer glass shell of a mercury vapour lamp! It 
> >>will radiate a lot of short wave UV (UV-A) which is dangerous for 
> >>eyes and skin, and it generates lot of ozone (O3). Good results 
> >>could be obtained without breaking the outer glass shell.
That was precisely the reason for my question (see the first post on this thread). I understand from my web searching that UV-A is the radiation band that actively polymerises the UV resist. I further understand that the more intense the UV-A radiation is the quicker the polymerisation. I have also read that the quicker the exposure, the better is the definition achievable. Seeing as the exposure unit would be fully enclosed, I don't see a problem with the eyes and skin bit. Anyway, from the research that I have done, it seems that the dangerous radiation bands are UV-B and UV-C; so your quotation is quite incorrect on that point but the UV-B and UV-C also is unblocked by breaking the glass filter. So the recommendation in that excerpt is appropriate for some purposes. However it is out of context so I cannot tell. The so-called solariums (facial tanners) rely on UV-A as their active radiation ingredient so it cannot be too harmful. Ozone has got me a bit worried though.
Still trying to get a range of views on whether mercury vapour is a better way to go than fluorescent.

> I'm inquisitive too...What are you really up to? You're coming 
> across like a "Man dressed in black".
> 
That is your opinion. Problem with the English language I guess. Re-read the thread and reflect on whether you are being just a teensy bit paranoid.
Regards
John C