Sanding plywood to remove Danish Oil

[Aurelius13100]

Hi everyone,

Here is my problem. I used plywood for a project, stained it (water based, so really easy to remove by sanding), and applied 4 coats of danish oil. Until the last coat, everything was fine, but after the last one, weird shiny wide lines appeared, visible from a certain angle only. I would like to start over the finish.

My question is : knowing that I used plywood, can I sand my piece to get the bare veneer back ? I'm a little afraid of sanding through it...

I sanded many times with 600 grit paper and steel wool 0000, but nothing seems to help. The veneer is not that thin (1mm for a 18mm plywood, the botton layer on the picture). The other pictures are the same area from various angles.

Thank you !

 

[AESamuel]

I may be wrong but isn't that just natural rippling in the woods surface? Oil finishes tend to bring out those features of the wood and it's normally one of the desired features of oil.

 

[Aurelius13100]

I may be wrong but isn't that just natural rippling in the woods surface? Oil finishes tend to bring out those features of the wood and it's normally one of the desired features of oil.

Those weird light vertical lines (second picture) were not visible after the second or third coat of danish oil, and are not visible when seen from the left... (third picture) It does not seem natural to me.

 

[jcassidy]

So you're talking about the lighter patches in the second picture? Pretty sure that's where you've got different thicknesses in your veneer. Oiling is not like painting or varnishing, you're not layering one impermeable layer on top of another - you're soaking more oil into the wood. I'd suggest what's happened here is that the surrounding darker colour is where the wood has absorbed more oil and water-based stain, and the lighter patches are where it's absorbed less.
You could try to validate this theory on an off-cut, by sanding down to various levels and applying your finishes in the same sequence.
If this is the case, then sanding back won't do anything.
You could and should looking into - oh I'm having a momentary block and can't remember the term - you paint the wood to match the surrounding wood with artists oil paints, before sealing under a varnish. The critical point is you do this only after staining/oiling, so you can colour match exactly, using really thin layers. This method is often used by restorers to match repairs to patina. Mixing colours is actually quite easy, there's some good youtube videos about how to mix oil paints.

**edit** Actually you don't have to colour match exactly, you have to match the tone (light vs dark). The human eye will just not process the colour difference when the tone is correct.

Hope this helps.
John C.

 

[Sgian Dubh]

I would like to start over the finish.
My question is : knowing that I used plywood, can I sand my piece to get the bare veneer back ? I'm a little afraid of sanding through it...

I'd leave well alone. It's technically known as 'blotching'. What you're looking at is where the colourant and finish has picked up and highlighted waviness in the grain. Lighter areas are where you are looking at the grain rising away from you, and darker areas (vertical stripes) are where the grain is rising towards you where severed end grain is more pronounced. It's likely that if you view the item first from one end and then from the other, that the area that was dark from the first viewing end will look light when viewed from the opposite end, and visa-versa, light viewed from one end looks dark viewed from the other. It's a bit like looking at a smooth haired pet, e.g., a cat, where its coat appears glossy looking from the head towards the tail, but quite dull or matte when looking from the tail to the head.

If you start sanding you're very likely to cut through the top layer of veneer at some point, and maybe at several points trying to get down to a white surface again, and even if you don't cut through anywhere you need the skills and knowhow to successfully apply finish products in a manner to either eliminate or largely hide blotching.

It's probably best to learn to live with what you've already got, but use the experience to perhaps improve your finishing skills for future projects. Slainte.

 

[jcassidy]

My dad spilt some Galveston anti acid stomach stuff on my counter...

Holy smokes, stripped the oil right off. I don't known what's in that stuff, but lads, its a wonderful stripper....