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Bubbles on wood when varnishing

  • 03-06-2020 10:11pm
    #1
    paddylonglegs
    Registered Users Posts: 3,516 ✭✭✭


    Hi folks.

    I am varnishing a table with polyeurathane. It’s looks like some bubbles have developed from the first coat.

    I had completely stripped the wood which looks like a veneer mahogany or teak. I then put 2 coats of wood dye on, and then started with the varnish.

    Any thoughts on why this has happened, and how I can avoid? I wouldn’t like to have to sand them back as I don’t want to damage the varnish.

    Any help appreciated.


Comments

  • #2
    Kaybaykwah
    Registered Users Posts: 3,083 ✭✭✭Kaybaykwah


    Sounds like you did a lot of prepping and that the surface is quite nice wood. Don't worry too much about it, it is normal to have a few bubbles from air buildup. You could sand it with very fine sandpaper like 600 grit or finer, but with a light touch. It is also normal to sand between coats, so it is okay to take your time with this. If you sand and take away the dust with a slightly damp rag, let the surface dry or dry it with a good soft dry one to make sure all the residue is gone and that the humidity doesn't create more bubbles. You can actually do a couple of sand, rag and varnish passes to make your project better. Is your varnish water based or oil, lacquer?


  • #3
    recipio
    Registered Users Posts: 2,804 ✭✭✭recipio


    It is either air bubbles from the brush or silicone contamination from a polish.
    They can be fixed by sanding back carefully starting with 240 grit up to 320 or 400 if you can. Buy a dedicated varnish brush from a good paint shop - they are about 10 euro and make all the difference.When the surface is ready vacuum the top ( compressed air is better is you have it ) and wipe down with 'Panel Wipe ' or 'Cellulose thinners' as a second choice. After that its a few coats of poly with a good brush -- air bubbles are less likely to form if you keep the coats thin.


  • #4
    CJhaughey
    Registered Users Posts: 14,906 ✭✭✭✭CJhaughey


    Just make sure that if you are using a compressor that the air supply is filtered, most compressors put a small amount of oil into the air and that also leads to fish eyes developing in varnish.


  • #5
    paddylonglegs
    Registered Users Posts: 3,516 ✭✭✭paddylonglegs


    Thanks for the advice everyone, appreciate it.

    Separately - the lacquer is a bit too glossy for my liking. I have heard that rubbing with wire wool and a top coat of bees wax is good to reduce the sheen but still have a nice satin finish?


  • #6
    recipio
    Registered Users Posts: 2,804 ✭✭✭recipio


    paddylonglegs wrote: »
    Thanks for the advice everyone, appreciate it.

    Separately - the lacquer is a bit too glossy for my liking. I have heard that rubbing with wire wool and a top coat of bees wax is good to reduce the sheen but still have a nice satin finish?

    Yes , wire wool with wax will give a lovely sheen - make sure its 0000 wool. Wax should be given a few hours ( preferably overnight ) to evaporate before buffing. I use a rounded brush in a drill for this - saves a lot of 'elbow grease.':D


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