shellac/wax damage from cork placemats

Howdy,

I finished a table top not that long ago with white shellac followed by hard shellac and then traditional wax over the top. It seems that the cork placemats I was using to protect the table are damaging the finish though. The only way to get rid of the marks is to get out the EEE and apply significant elbow grease which makes me think it isnt just the wax on top being marked, but the shellac as well. It isnt anything spilt under the placemats, and it occurred under more than one of them. It isnt heat related, because it even happened under the cork drink coasters (wine glasses on top - no hot coffee). I had thought the hard shellac sounded like a nice robust finish, but I'm not so happy now. Has anyone had a similar experience or know why this might be happening?
Attachment 153224

thanks

How old was the shellac? - Use before date on both shellacs?

How many coats of each?

How soon after last coat was Traditional applied?

How long did you wait before using the placemats and coasters?

What timber is it?

Was the timber kiln dried or air dried?

Looks like moisture damage, which shouldn't happen on hard shellac.

Try wiping the surface down with turpentine and a clean soft rag to remove it. If the white disappears it's most likely the wax.

The photo is a little misleading in that the marks aren't really white, it just looks that way because of the angle trying to get them to show up on the photo. They are more like something in the placemats has just eaten its way through the finish.

shellac was 2 or 3 months old.

many coats of white shellac, although most sanded off (first shellac project), two or three coats of hard shellac, and one of trad wax

wax applied about 3 weeks after hard shellac

4 or 5 weeks before use after that.

timber is red gum (I think)

no idea if kiln or air dried

I tried wiping with turps, and scrubbing with turps, but the marks weren't coming out in a hurry.

The finish was far from perfect as apparently I really hadn't prepared the table top well enough before getting the shellac on it, but I was happy enough with it to move on to the next project and keep this as an example of needing to do better next time. I would prefer not to keep the table covered up with a table cloth to protect the surface though.


thanks

OK here goes. Red gum.... Hmmmm even kiln dried can have a high moisture content.

I doubt it's the Hard Shellac that's been damaged as much as the white shellac below. The hard will resist the damage from water and heat etc, but what's below can still be effected as heat can draw moisture out of the timber into the layers of shellac below. Same can happen if an oil has been used beneath hard shellac or even another coating like polyurethane.

Best to use Hard Shellac from the start to the finish then there shouldn't be a problem. I would never use shellac on redgum, but then again I would never use redgum for anything more than stumps or fence posts.

If you still have them, check on expiry dates (best by dates) on the bottles of both shellacs. You may have only had it for 2 - 3 mths, but it could have been sitting on the shelf in the shop for 12 months or more.

I can't really think of an easy way to fix this other than stripping the table and starting from scratch. Preferably with another product like Organoil, which really loves redgum.

Cheers - Neil

Thanks Neil, I'll put timber selection down as another one of my "learnings" from this project, I was just trying to match the red ironbark floorboards. They have an oil finish, so maybe I should have taken the hint!!

I'll do some more experimenting before I sand off the shellac. The table frame (European Beech) looks very nice with the shellac finish, so I'm not ready to give up on the top just yet. I have tried to get a better view of the surface pitting with the macro lens - unfortunately it shows the dodgy job I did of wiping on the shellac as well!! Not sure I was clear above, but the table sat unused and looking good for 4 weeks while I was on holidays and the marks only appeared after usage when I returned from hols. I'll swap to some different placemats for tonights feast and see if anything similar happens.Attachment 153333

Hi guys,

I've been using Mirotone on my furniture for about 20 years, just strip off the shellac and spray on about 4 coats of Mirotone,(which is the mainstay of the furniture industry) and you wont have any trouble, talk to your local Mirotone dealer for the specs etc. Good stuff, sorry to say leave shellac for artistic and ornamental things nowadays, best and most beautiful for that.

Regards...Oddjob1:)