poly over tung oil ???

[John C Bush]

Making a NE desk with Big Leaf Maple and wondering if there is any benefit/limitation using Tung Oil as the first coat to bring out more grain character before using a poly for a more durable top coat. I've done the first coat on the drawer pedestals and it looked good when wet and flattened--as expected-- when dry and haven't done 2nd coat yet. Not sure how much oil is in the poly I'm using and not sure if more oil or initial straight oil first coat would make a difference or effect the durability of the poly top coat. I usually just gettertdun but this is for a friend and I would like to max the nice character of the slab. Thanks, John

[Jim Becker]

Just let the tung oil cure for at least 24 hours or so before top coating with an oil based product. But you'll also find that just using the oil based finish will give you essentially the same look without the added step. I only use oil as a first step because I use waterborne finishes and want the amber effect that the oil gives in addition to the "grain pop" along with the wax free shellac to act as a barrier coat. Sometimes just the shellac is enough for that.

[John C Bush]

Thanks Jim,
That was my guess-- already enough oil effect in the poly formula. I'm not up to speed on shellac--suggestions on good reference info?? Thanks again, John

[Andrew Seemann]

A coat of dewaxed shellac (Zissner's SealCoat) is often used as a finishing step to add an amber cast to a finish, often very helpful with water based finish which can make wood look greyish or bluish.

It's main use though is a barrier coat. It sticks to everything, and everything sticks to it, so it solves most "attitude problems" between finishes (such as oil & water base; water dye & and water topcoat). It also gets used as a sealer coat (hence the name ) to prevent blotching of oil based finishes.

I tend to use it under poly for both blotch control and to keep any oil from a stain from mixing in with the poly if it hasn't fully cured. It also can add a little more visual depth to the finish.

Shellac also makes a very nice finish, for things that won't get wet or suffer a lot of abrasion.

[Jim Becker]

Thanks Jim,
That was my guess-- already enough oil effect in the poly formula. I'm not up to speed on shellac--suggestions on good reference info?? Thanks again, John

John...do some test pieces on scrap of the same material and do the entire finishing regimen through at least the first application of top coat.. Don't experiment on the real project. Try different combinations and see what looks the best to you.