Wiping Varnish Question

I dug up a mystery "cedar" stump a while back and have been using the wood for small projects as I tinker in the shop. I don't know what kind of cedar it is, but it's very purple and clear of knots and resin pockets. It is extremely dry though. Sanding produces a very fine dust that gets everywhere.
I cobbled together a letter opener of some maple I had sitting around and a chunk of this stuff (the "blade" and "pommel" are maple and the handle is the cedar), and I applied some Formby's Tung Oil Finish to it as a finish. After 7 or 8 coats, I'm finally to the point where the finish has stopped soaking into the cedar and is starting to get glossy.
I do some research on rec.woodworking today and find that tung oil isn't recommended as a finish for cedar due to the oils reacting. I then find out that Formby's isn't really tung oil, but a wiping varnish. My question now is, this:
Is the finish I put on the cedar going to go funky in a few months? If it is, or even is there is a better than 2/5 chance that it will, can I put anything on it like shellac or a polyurethane finish?
The Formby's site really wasn't very helpful, which is why I'm here.
Thanks, Nathan
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I have been using shellac on some old incense cedar( I believe that is what you have) and it seems to do ok, I can't say what it will do after years though, cedar has always been a problem to finish, the resin never seems to set in the wood.
I also have a large quantity of old cedar logs and stumps, some of it has been dead for 35 years and most of the sapwood has decayed, but the heart is still good looking and as with yours it is very dry. The main problem I have using it is that when cut for use it will begin to develop hairline cracks within hours.
I end up roughing out slabs and blocks, then working around the cracks.
Basilisk
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.