shellac back-up

[Steven Vigeant]

Is it acceptable to brush on shellac on to the back of a fresh matte reverse gild as a backup?
For example.
1)painting a box on the inside of a window with enamel and hardener over masked off letters.
2)pull out the letters right away. wait briefly or as long as feasible, then quick size.
3) patent gild, then apply shellac immediately, possibly tinted ocher? over the back.
4) then possibly putting on a second coat of enamel or clear coat on as soon as feasible.

or second example.
1) using a paint mask to apply quick size for matte gold letters with no outline on the inside of a window .
2) then clearing with shellac with a brush.
3) then applying window spar almost immediately?

[Kent Smith]

Shellac has been used as an intermediary coating since it has a different base than enamels, varnish or Japan and will not rewet them. It also has enough surface tension that you can paint over it. Using it as an alternate coating between coats of varnish or enamel has some merit as long as the first coat is dry, ohterwise the first coat can be sealed wet and fail.

[Dan Seese]

I've used shellac as a backup to matte reverse gild in the past. I would add a bit of gold bronze powder to the shellac and then back it up. Seemed to work great because, as Kent mentions, it creates a barrior that doesn't rewet what is underneath and because it dries so quickly you can move along quickly to the next step.

However, I quit this practice when I had to return to a job site (about 3 hours drive) a month or so after doing a window. The sun would hit the surface of the glass and heat things up. Then it created bubbles in the painted areas where the shellac had covered some paint - including some of the matte gild. I think the reason had to do with the fact that it sealed things off. As the paint tried to cure, the outgassing bubbled the paint. Also, I noticed some brittle areas around the gold. I don't know how elastic shellac is but my guess it that using these layers of materials that have different drying properties was a recipe for failure.
Hmmm, seems like I'm often posting about failures here!

My guess is that shellac is fine for indoor work, especially used as a barrior. Rick Glawson used it all the time in various applications. Because of this experience, I haven't used it for several years.

[Jerry Berg]

Dan,

What method of back up on matte for outdoors are you having success with now?

[Dan Seese]

Jerry,

I usually like to add a bit of gold bronzing powder into some varnish or into the same medium I used for the matte center and use that as a preliminary back-up. The bronze powder is close in color to the gold leaf and gives a little reflectivity and opacity so that it helps hide any holidays.

Similarly, One-Shot metallic gold works. Or Dekor Ochre Back up, though I prefer the method I first described. If I have other colors which need to be added which will overlap onto the gold, it seems to hide things well.

Than I follow it with the gilders black back up, available through Letterhead Sign Supply. That last step is fast-drying and provides a hard protective finish.

Whether or not I follow this course depends somewhat on the other things going on but this is somewhat normative. Maybe my method ends up adding an additional step which ultimately cuts into profit. I just like the end result.

Dan