Egg Wash

What is an egg wash?

When you have completely sanded your guitar and are getting it ready to apply a finish, you can first give it an egg wash. It is used to raise the grain and leave behind a very fine seal.
Earlier this year, when the NAMM Show 2005 was held at the Anaheim Convention Center, a friend of mine, Josep Melo (www.meloguitars.com) from Barcelona, came out to display his guitars at the show. I met Josep at the Jose Romanillos workshop. He is a very close friend of Jose Romanillos and a fine guitar builder.
During his week stay in Southern CA he was kind enough to share many of his trade secrets. Most of the questions I had were related to finishes. I was ready to put a finish on the guitar that I had built in Spain with Jose Romanillos. My plan was to apply a French polish to that guitar and nitrocellulose spray lacquer finish on another. He told me to first apply an egg wash regardless of what finish I was going to use.
The purpose of the egg wash is to raise the grain after sanding and just before sealing the wood before the finish. Normally you can just dampen the wood with water after sanding to raise the grain. It also leaves behind a very fine layer which helps coat and seal the wood before the sealing process. You really cannot see what is left behind after the egg wash.
The process consists of cracking an egg and separating it into a small cup or bowl, leaving only the egg white. Making sure that there is no trace of egg yolk in the bowl because once you introduce the yolk into the mixture, it can spoil the egg. It is not necessary to mix the egg white prior to application. Use a small paint brush to first apply the egg on all areas of the guitar that have colors that can bleed. Use the same process as if you are starting to seal the instrument right before applying your finish. Apply the wash on the soundboard first. Continue to brush on to the back and sides. Brush it on all parts of the guitar. Brush throughout until you finish the egg. Let it dry completely before fine sanding the raised grain, he recommended to dry overnight. You are now ready to apply your finish.
I asked Josep how many eggs are necessary for the process, and he replied that only one egg is necessary for the process to coat a full size guitar once or twice. I told him that it was a waste of a perfectly good yolk. He told me that if I save the yolk and add a few more eggs, mix in some onion, potatoes and olive oil, I can make myself a great Spanish tortilla.