It is a common mis-conception that glass blocks 100% of the UV light. Check
this link http://www.jersey.net/~edsci/techsup/GlassCurve.pdf for a graph
showing transmission at various wavelengths for 5mm thick glasses.
The UV portion of the spectrum is generally taken to be 400nm or less
(1000nm = 1 micrometer, or 1 micron if you prefer). In this list I am
familiar only with the first three types listed: Borofloat would be similar
to window glass, Pyrex is Corning's name for tempered glass, and BK7 is
commonly used for mirrors or lenses.
Optical plastics, e. g., CR-39 and polycarbonate that are used in plastic
eyeglass lenses, have UV absorbers in the mix but I doubt that the windows
in the Europa have an absorber, and your experience confirms this suspicion.
Best regards,
Rob Housman
A070
----- Original Message -----
From: "LTS" <lts@avnet.co.uk>
Subject: Re: Use of White Pigment with Ampreg 20
> I am not on a topic that I know much about here but:
>
> 1 I thought Rayban used glass in their sunglasses for 100% UV block????
> 2 I get a great sun tan whilst flying and I have a plastic canopy????
>
> Jerry
> LTS@avnet.co.uk
> www.avnet.co.uk/touchdown
> ----- Original Message -----
> From: "J R (Bob) Gowing" <gowingjr@acr.net.au>
> <roger.mills@btinternet.com>; <europa@avnet.co.uk>
> Subject: Re: Use of White Pigment with Ampreg 20
>
>
> > Thank you fellas for your comments.
> >
> > Dave S, I take your point that the UV is a serious matter and that is
the
> > reason for my reply to Roger as follows:-
> >
> > Roger, I put a lot of laminated glass in the front extension of our
> house -
> > to get the plastic layer in between the 2 layers of glass. That is the
> part
> > that keeps out the UV.
> >
> > Fred F, I intend taking your advice and forget about using any White
> pigment
> > in the epoxy itself.
> >
> > Thank you all for your inputs.
> > Sincerely
> > JR (Bob) Gowing in Oz Kit 327
> >
> > ----- Original Message -----
> > From: "Dave Simpson" <davesimpson@londonweb.net>
> > Subject: Re: Use of White Pigment with Ampreg 20
> >
> >
> > > Bob,
> > >
> > > At work, a sub-contractor used white pigment in the epoxy/glass lay up
> for
> > a
> > > very large radome mounting ring (3m dia.) for a microwave test site.
> The
> > > rig has been completely outdoors for almost 4 years now and shows no
> sign
> > of
> > > UV degradation. It also has a blue foam base. The laminate was much
> > > thicker that our Europas but the environmental exposure was more
severe
> > too.
> > >
> > > Dave Simpson
> > >
> > > ----- Original Message -----
> > > From: J R (Bob) Gowing <gowingjr@acr.net.au>
> > > Subject: Use of White Pigment with Ampreg 20
> > >
> > >
> > > > I have just read the pamphlet that came with my latest supply of
Slow
> > > > Hardening Ampreg 20 and 2 year shelf life. It states that up to 10%
by
> > > > volume of SP epoxy pignents can be added to the resin component and
> then
> > > > this mix can be combined in the same old weight ratio of 100:25.
> > > >
> > > > It may be that using the available white pigment in the finishing
> phase
> > > > might reduce the amount of paint needed for satisfactory cover and
UV
> > > > protection.
> > > >
> > > > Has anyone something useful to report about using SP white pigment
in
> > the
> > > > mix to finish their wings?
> > > >
> > > > JR (Bob) gowing, Kit 327 in Oz.
> > > >
> > > >
> > > > The Europa List is supported by Aviators Network UK -
info@avnet.co.uk
> > > >
> > >
> >
>
>
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