Announcement

Collapse
No announcement yet.

Finish on top of Shellac?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Finish on top of Shellac?

    Hey everyone, just completed a small refinishing refurbishing on an old antique birdseye maple side table. Original table was a shellac finish and I removed all the old with Methyl Hydrate then resanded some damaged areas. I reapplied shellac 5 coats and finish came out looking really great. A few days later I placed the table in the house, put a lamp on it and someone laid some mail and magazine on it. Later on, discovered the shellac had bonded to the magazine and the lamp base. Bunch of paper shreds and lamp felt ended up embedded in the shellac. No idea why. Temp and humidity inside were constant, finish seemed hard at the time. Can anything be put on top of shellac to make it a harder surface? dont want to wax it unless absolutely have to. Once its waxed, you can never really go back.. Any ideas??
  • Thread Continues Below...

  • #2

    Re: Finish on top of Shellac?

    Wax is actually a great idea IMO It's my go-to finish over shellac for a number of applications. Wax can be removed with mineral spirits very easily if necessary.
    WCraig and Frank D. like this.
    The difference between a master and a beginner: The master has failed more times than the beginner has even tried.

    Comment


    • #3

      Re: Finish on top of Shellac?

      One more vote for wax.

      If the shellac is de-waxed, then you can apply a polyurethane varnish over it, but with a thicker coat of shellac (more than two thin coats), the poly will be more fragile (white marks when banged because it de-bonds).
      Frank
      SPCHT

      Comment


      • #4

        Re: Finish on top of Shellac?

        As long as the shellac is dewaxed you can put any finish over top of it. Very versatile finish. I wonder about how old the shellac you put down was though. If it is too old it stops hardening properly.

        Comment


        • #5

          Re: Finish on top of Shellac?

          Originally posted by Grailwoodworks View Post
          As long as the shellac is dewaxed you can put any finish over top of it. Very versatile finish. I wonder about how old the shellac you put down was though. If it is too old it stops hardening properly.
          Agree about the age of the shellac. I know what you mean about anything goes on top, but one recent poster applied a penetrating oil finish (tung oil) over shellac...which doesn't work, so it's good to mention that any film finish goes over de-waxed shellac, not penetrating oils like tung or linseed.
          Frank
          SPCHT

          Comment


          • #6

            Re: Finish on top of Shellac?

            Yes, sorry, any film finish. Good catch Frank.

            Comment

            • Thread Continues Below...

            • #7

              Re: Finish on top of Shellac?

              Originally posted by Windhaven View Post
              I reapplied shellac 5 coats and finish came out looking really great. A few days later I placed the table in the house, put a lamp on it and someone laid some mail and magazine on it. Later on, discovered the shellac had bonded to the magazine and the lamp base. Bunch of paper shreds and lamp felt ended up embedded in the shellac. No idea why.
              The shellac wasn't fully cured and was still off-gassing.
              5 coats would take about 2 to 3 weeks to fully cure, unless it was sprayed on in thin coats, as each successive layer melts into the one below it. Even though the top surface feels hard to the touch, the shellac is still soft underneath. Once all the alcohol has percolated upwards and out, the finish will be fully cured.

              Solvent off-gassing and soaking into the items on the table's surface caused them to act a little like a sponge soaked in alcohol and locally redissolve the surface layer. As the shellac hardened, the items stuck to it.

              My experience with coating shellac is that you can put a lot of different finishes directly over it as long as the first couple coats are applied very, very thinly and each is given time to cure so you can catch any adhesion issues. I spray all my finishes so it's fairly straightforward to dial back the gun and do this. Not so easy if you are brushing or wiping.
              Whilst dewaxed shellac is definitely the preferred option if you are coating with a more resistant film finish, careful prep and very light thin first coats may also work. Not guaranteed, but lots of folks do it, including me.
              I have heard of folks applying a layer of dewaxed shellac over the regular stuff, then coating with waterbased or regular poly, but I have no first hand experience.

              Hope that helps
              Paul

              Last edited by Paul O in Paris; 09-17-2020, 07:19 PM.
              smallerstick, [email protected] and 2 others like this.

              Comment


              • #8

                Re: Finish on top of Shellac?

                Many thanks for the input folks. I have been down with pneumonia for weeks and just returning to the living now. I will start by reapply another top coat of shellac and leaving lots of time for it to cure before I let the table be used. If still an issue looks like I will go to a ply or varnish topcoat. Thanks again for sharing your experience.

                Comment


                • #9

                  Re: Finish on top of Shellac?

                  shellac has a low temperature resistance
                  I wrapped an antique radio in newspaper and it was
                  in the hot attic. Newspaper stuck to it

                  i have a shellac table. if i put a hot coffee on it the cup gets stuck down. the finish is almost worn off.
                  i dont see a mark but it's weird when it catches you off guard.

                  if thats my biggest issue im doing ok. hope you heal well.

                  I coated some wood cabinetry near my oven shellac then poly. tthe countertop edge. it stuck ok but the heat affected it a little.
                  it can be good to have that down if you paint stuff. easier to heat strip if you ever want to get it back off.
                  Last edited by phil; 11-23-2020, 02:39 AM.
                  “The time you enjoy wasting is not wasted time.” -Bertrand Russell

                  Comment


                  • #10

                    Re: Finish on top of Shellac?

                    For what it's worth here's a video from Mark Spagnolo aka the Wood Whisperer where he tests polyurethane over waxed and dewaxed shellac. He found no adhesion problem with either. https://www.youtube.com/watch?v=7kCnmW6mKCM
                    Last edited by Doug G; 11-23-2020, 04:16 PM. Reason: spelling

                    Comment

                    Working...
                    X