I am trying to develop a “best practice” for a mosaic project and would appreciate some advice.
The project is a trivett (ite, to put a hot dish in the kitchen or dining table) that has a plywood base with quarter round molding surrounding the plywood square.
The plywood must be sealed in order to protect it from water in the tile adhesive and grout. The instructions say to dilute “craft glue” with 4 parts water and 1 part glue. After not finding anything that said “craft glue” I assumed it was a reference to Elmer’s white glue. Of course, adding the water made it a very watery sealer.
Then someone said that “craft glue” refers to a specific glue that is very thick and would need thinning to be a wood sealer. Several checks at big craft stores produced nothing that says “craft glue.”
The goal is to seal the wood but still allow the tile adhesive to stick.
Cost and dry time are concerns.
Replies
There are a lots of different things that are collectively called "craft glue," some of which aren't even soluble in water. So, I don't think you can use the information you have without further details.
Dewaxed shellac should work well as a sealer. You can go to your local home center or hardware store and get a quart can of Zinsser Seal Coat and an inexpensive bristle brush. You may also want a can of denatured alcohol for clean up (you can also use ammonia). Total outlay should be less than $20, and give you enough material for a lot of trivets.
-Steve
Will shellac sealer affect the adhesive? What "cut" would you recommend?
Shellac shouldn't interfere with adhesion as long as it's dewaxed. (That's why I specifically recommended Zinsser Seal Coat.) Two coats of a 2-lb. cut (which is the way that Seal Coat comes in the can), applied about an hour apart, should be fine.
-Steve
Edited 10/24/2007 12:09 am ET by saschafer
I have some 2 lb cut of shellac mixed up. I'll try a test on one and two coats and adhere some tiles to it. Then I'll turn it upside down and shake it and see if any fall off. : )
Thanks for the comments.
Steve.. My Step Dads name.. Nice Guy..Sorry about interfering with this post but I had to ask.shellac.. What "cut" would you recommend?Why is it necessary to 'cut' the shellac. The reason I asked is I am making a Child size rocking chair made of Riff and QS red and white oak. Yes two different woods.. 'Full strength' out of the can works for me but 'I have been wrong before'....I find that not cutting works.. I have to sand it anyway!Your opinion...Thanks!
"Why is it necessary to 'cut' the shellac."
It's not necessary, but it can make finishing a little easier. If you use Seal Coat, it comes as a 2 lb. cut (which is just fine as it is for most purposes). The other Zinsser shellacs come as a 3 lb. cut. My experience is that a 2 lb. (or even 1-1/2 lb.) cut flows on more smoothly, with less in the way of brush marks.
-Steve
It's not necessary.. What I thought also..Just looking for your opinion. Thanks!
The simplest thing to do may be to do nothing. Plywood isn't drastically affected by moisture, the temporary exposure to the moisture in the grout will probably do no harm. I'd do an experiment before looking for a sealant.
John White
Yestermorrow School, Waitsfield, Vermont
One issue is the effect of water on plywood during the construction process. There will also be some amount of water involved in cleaning the trivet--hopefully a damp cloth with minimal water
Another issue--will the dry bare plywood leach water from the adhesive and have any effect?
I am testing the water resistance of plywood coated with a 1:4 dilution of Elmer's glue.
Thanks for your comments.
This forum post is now archived. Commenting has been disabled