Clear Polyurethane Gloss

Triarius wrote:

I'm told by my contacts still in the paint industry that all polyurethane formulations yellow with time and exposure, especially to ultraviolet, but that the degree of yellowing varies significantly.

So as long as I keep my models out of the sun tanning table and away from windows, they should be alright for awhile?

"Hey honey... have you noticed if our furniture has turned noticably yellow yet?"

Thanks guys. Big help. The water-based furniture finishes sound promising.

Andrew

I'm told by my contacts still in the paint industry that all polyurethane formulations yellow with time and exposure, especially to ultraviolet, but that the degree of yellowing varies significantly.

New formulations of polyurethanes and acrylics are constantly being developed, making generalizations difficult. What works one year may be very different the next. My advice is to test any product not made specifically for modeling applications on scrap before you risk it on a valuable kit.

Humm... I'm wondering now...

What about the water based polyurethane such as what is used for furniture finishes?

I bought a gallon of that stuff, finished a bunch of furniture pieces long ago and it hasn't showed any signs of yellowing yet. The stuff was great to work with compared to the old smelly stuff. It goes on milky but dries clear within 30 - 45 minutes and ready for the second coat. I wonder if it could be used on models if sprayed in thin coats?

Has anyone tried it?

I'm not familiar with that particular product, but polyurethanes do have a fairly strong tendency to turn yellow, especially when exposed to ultraviolet light. They also tend to cure slowly, especially if it is cool and damp. Ironically, exposure to ultraviolet light will speed the cure (and increase the yellowing).

If you want a high gloss, I'd suggest Future Floor "Wax" which isn't a wax at all, but rather a high-gloss, clear acrylic. The stuff is wonderful. In this forum there is a sticky topic called "The Complete Future." It will tell you almost everything you need to know about Future, including where, and under what names, to find it.

There are loads of high gloss coats avaible from the various paint brands (humbrol, polly scale, tamiya, testors etc.)

Using non-model paints can often give undesired effects (as you found out) but Future (johnsons floor finish) is also a viable alternative.