Helmsman Spar Varnish - not hardening

[Jon A]

Hello,

 

I made some coasters out of some western red cedar I had in the cut-off bin with a curved stripe of 1/16" mahogany veneer left over from a strip-built kayak project.  Since they are coasters and will see a lot of water, I thought I would use some old Helmsman Spar Varnish I had in the cabinet.  Seemed like a good idea anyway...  

I strained the finish and put it on with a brush.  It was much thicker than I would have liked and it picked up a ton of debris.  In retrospect, I probably should have thinned it with some mineral spirits or just used a wipe-on poly.  Of course I waited until after I began experiencing problems to do a search on this site.  It sounds like HSV doesn't harden as much as poly so that it can expand and contract with the wood in exterior applications.  It was around 55 degrees when I applied the finish and probably dropped down to the 40's at night (unheated garage shop in Massachusetts).  

 

It sands but gums up the paper a bit.

 

Am I better off scraping it mostly off with a card scraper or razor and starting over with wipe-on poly? 

 

I am really annoyed at myself for using this old stuff.  I had some Interlux varnish in the same cabinet as well as some different oil-based polyurethanes.
 

Thanks in advance for any suggestions!

 

-Jon A.

[Boatworks Today]

highly unlikely it's going to harden in those temps; most other finishes as well.  Best to have 60 or better throughout the 'cure cycle'.  If you're able to move the pieces indoors it should do it's thing but may take a day or two or three. 

 

When the material is thick in the can it also goes on heavier than normal giving a thick film which will take longer to set up.  If you start to see the surface wrinkle it's a lost cause and will have to be removed.

 

FWIW varnish doesn't really go bad.  Providing it isn't hard in the can, it can be re-constituted with mineral spirits to thin it back out.

[Jon A]

I think you are right about the temperatures... it was in the upper 70's yesterday and that seems to have done the trick.  The varnish has cured.  It is still a bit soft (you can leave a mark with a finger nail).  I think I put it on too thick.  I was trying to fill a couple of knots... I think I will use some SystemThree epoxy instead then sand everything down and either put some varnish thinned with mineral spirits or wiping poly on.  Good to know that varnish doesn't really go bad... that provides some reassurance!

 

Thanks!

 

-Jon A.