Surface Gild Failure

Rick Sacks · Post by **Rick Sacks** » Sat Jul 29, 2006 8:27 am

We sealed the incised letters of this redwood slab with a few coats of shellac, then a coat of 1 shot white, then a tad of imitation gold into Lafranc slow size. Two days later we gilded it with 23k and flipped the board and did the same on the other side. Next day it was loaded into a truck and driven to a hot sunny location where the customer noticed bubbles rising about the size of a nickle under the leaf. I asked him to in prick a couple and press them and he found no moisture in there. The surface of the board surrounding the gold is stained and not a sealed surface that could trap anything inside. Any ideas?

Doug Bernhardt · Post by **Doug Bernhardt** » Sat Jul 29, 2006 6:32 pm

I dunno Rick....you seem to get away with murder in California. Is this process with shellac usual for you? Has it worked before? Shellac is great stuff but I couldn't use that outdoors around here.

Doug Bernhardt · Post by **Doug Bernhardt** » Sat Jul 29, 2006 10:38 pm

Just to add...me thinks the shellac and heat combo is the culprit...size takes SO long to set and cure.

joe cieslowski · Post by **joe cieslowski** » Mon Jul 31, 2006 11:20 am

I'm just gonna think out loud here. The moisture content of a lot of dried woods is higher in the center. Generally only about 10% of the surface of a board reacts to the changes in enviormental conditions. When the incised letters were carved and quickly sealed, it is possible that a small amount of moisture was temporally captured and bubbled out when the sign was placed into a heated enviorment. Air causes bubbles. It happens when moisture turns into a vapor. When the bubble is broken, the moisture leaves with the air......it feels dry. Just a thought.

BTW, Are the bubbles still appearing? Or was it a one time event?

Joe,

Rick Sacks · Post by **Rick Sacks** » Sun Aug 13, 2006 9:38 am

At this time the bubles rise and set and continue. They can be popped, but appear next to where they were. There is also some sap risig to the surface. I tend to think it's moisture in the wood. This was milled here on the coast a couple years ago and after gilding was moved inland to a much hotter and drier climate. I don't know of anything to stabilize this sign other than waiting a long, long, time and then possibly re doing it.

joe cieslowski · Post by **joe cieslowski** » Mon Aug 14, 2006 1:08 pm

Rick,

Just another question.....or two

. You said you finished the other side the same way....are both sides blasted? You said it was installed in a sunny location.....Do both sides get the same amount of sun? Has it cupped any? On the sunny side?

If there is cupping towards the sunny side moisture is the culpret. Is the gold bubbling on both sides?

Sorry for all the questions.....

Thanks,

Joe

Rick Sacks · Post by **Rick Sacks** » Tue Aug 15, 2006 7:45 am

Joe,
No cupping, the board is four inches thick and better than three feet wide and fifteen feet long. There is some checking though and that is not a big problem. The summer sun hits both sides through the day. The letters are carved into the flat smoothe surface, no blasting.

Post by **Ron Percell** » Fri Sep 08, 2006 10:34 am

Disney experienced a simular experience with bubbles when finishing the Animal Kingdom, it ended up being carved wood that was infested with bugs, they had to place all of the carved projects into shipping containers and fumagate, after refinishing, it happened again, this time due to the bugs decomposing. Many signs were wet and being installed the day of the opening of Animal Kingdom.

In this case Rick, I believe that this problem is moisture and not enough dry time. The Shellac doesnt out gas and is cured withen 1 hour. I've seen this happen when the primer hasnt had a full 24 hours to cure, then the panel is placed in the sun and the bubbles began, and at other time I've seen the sun sweat pitch/sap to the surface.

Monitor this project as it settles in to it's location, continue to pop the bubble, once it is stable, you may want to redo the affected lines of copy.

As far as the gold size, only pure pigment is recomended for tinting to avoid adverse affects.

Good Luck