Digital BW, The Print

----- Original Message -----
From: "Ernst Dinkla" <E.Dinkla@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Saturday, September 21, 2002 5:55 AM
Subject: Re: [Digital BW] Coating prints with Epoxy?


>
> ----- Original Message -----
> From: "jhanson_mad" <jimhanson@...>
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Sent: Saturday, September 21, 2002 1:15 PM
> Subject: Re: [Digital BW] Coating prints with Epoxy?
>
>
> > Guys,
> >
> > Our local Woodcraft sells a product called Mirror Coat made by System
> > 3 Resins.  One of its stated uses is for bar and table tops.  Don't
> > think the epoxy will yellow, but may be concerned with a print
> > reacting and changing.  I have not used this product.
> > Jim Hanson
>
> A lot of the polymeres have problems with yellowing. For many polymeres it
> was even difficult to get them transparent without a tint in the first
> place. Often you will see that they are a bit grey. Instead of getting all
> of the colour out they added some colorant to get the neutral tint.
> Acryl has the best optical properties. The disadvantage is that it can get
> brittle if applied in thicker layers.
> PVA has nice optical properties but isn't water resistant. Polyurethane
> initially was very yellow, can't comment what has been done to get it so
> clear and I have no knowledge whether it will show yellowing when it gets
> older. It is a very tough resin otherwise. Epoxy isn't known for its
optical
> specs. As with any material the thinner the layer the better the
> transparency, but why start with a material that isn't that good in
thicker
> layers.
>
Ernst,

The two polyurethane coatings I tried, both labeled as "non-yellowing" did
indeed yellow with in a few months. These were products made for wood
finishing so the standards are probably not very high in this regard. In
general I would urge people to start with what they find in their art supply
store. You will be amazed at what is available. The stuff in the hardware
store is for the more adventurous and should be entered into as an
adventure. The other sorce of materials are various coating made for the
sign and banner industry. I tried ClearSheild a vinyl coating for outdoor
banners that is holding up well so far.


Martin Wesley

http://www.borderless-photos.de/guests.html