Shellac sanding sealer - problems

[JangoTrooper]

Hi,
I usually use shellac sanding sealer for my wood projects on my hardwoods. Which I use odour free spirits to clean, shellac as a coat. I do also sand down to 400 grit. I usually apply two coats of this minimum.

Once I’ve done I use a beeswax finish to buff up on my drill press using a polishing mop.

Issue I’m having lately is leaving the coats during the night the finish seems to show a white, chalky appearance, I’m only using the shellac and white spirit process at this point. No beeswax yet.

Anyone know what’s going wrong? I’m using oak and walnut hardwood on my latest project. Confused with the white chalky appearance. Causing a nuisance on finishing. Any reasons and suggestions?

 

[Doug B]

Sounds like a problem with moisture. is it cold where you’re applying the sealer?

 

[JangoTrooper]

Yes it is cold. Winter weather and all.

 

[Droogs]

You are trapping a layer of moisture under the shellac. Basically the same as a ringstain on a table. Leave some heating on overnight to stop this happening and for the stuff already done treat in the same way you would a coffee cup ringstain. ie spread a little lighter fluid on and set it alight and then blow it out after 3 or 4 sec. This will flash off and soften the shellac enough to let the moisture out. then leave to cool

hth

 

[JangoTrooper]

Thanks for that. I think it’s trying to rush a project to much. I will bring the project in the house more in future, especially winter time.

 

[Armagh]

I've that problem before and was advised to stop using white spirits ad my cleaner. I'm definitely far from an expert though.

 

[AESamuel]

I've that problem before and was advised to stop using white spirits ad my cleaner. I'm definitely far from an expert though.

I don't know if residue from white spirit would cause milky shellac, however I was always taught to use the same solvent in the finish to clean. So clean with alcohol for shellac, white spirit for poly etc.

Doug is probably spot on with moisture though. Shellac hates moisture!

 

[Sgian Dubh]

White spirits is, emphatically, not the solvent to use with shellac - it doesn't mix with it, and it won't dissolve it when the shellac is dry, so I'm puzzled that mention has been made of white spirit in this thread. Industrial alcohol (meths) is the solvent/diluent for shellac, and it will soften cured shellac, and can even be used to strip a failing or failed coat of shellac.

The white spots or milkiness that are the subject of this thread are, I suspect and as others have said, moisture condensing out of the air and getting trapped in the polish as it cures. Apart from setting fire to the film, one potential solution suggested, another solution might be to put some alcohol (meths) into a ball of cotton wool and wrap this is in a fairly fine lint-free cotton cloth (hanky maybe or T shirt) thus making a polisher's 'rubber'. Then use this rubber to gently wipe over the surface a small area at a time. Basically, swing the rubber backwards and forwards so that the cotton cloth gently brushes the polish surface to soften it a bit to let the moisture out. Start cautiously, barely skimming the film surface to start with, and get more aggressive as you become familiar with how the shellac is reacting. The swinging motion of the rubber is somewhat analogous to an aeroplane touching down on the ground and immediately taking off again. Slainte.