overcoating oil/varnish finish

[Jerome B]

I verntured out of my shellac comfort zone and tried some Watco danish oil finish and now I am wondering what I can top coast it with. Wait let me back up. I am doing a table top, walnut which had some sapwood streaks in it. I Wanted to experiment with staining out the streaks, so I used some water soluble Walnut crystals.

It worked like a charm. Although instead of using my paint brush as a chisel point I gave the whole surface a wash. I was a little surprised by how dark that it came out.

My next step was to top coat it. I have been experimenting with historical stains and I had some Watco danish oil handy and so I thought what the heck. I need to learn how to use the stuff. This is as good of a place as any.

Well.... What I didn't quite realize was that the watco was a oil/varnish finish and that it provided little protection against water transfer. That nice stain that I laid down is not staying where I laid it.

I guess that I could top coat it with shellac, but I need to learn more and experiment more with oil type finishes. I am thinking of trying a varnish like Waterlox. My only concern is that I am putting something that gets hard on top of something that doesn't get hard. I am afraid that I will gets cracks.


What do you guys think?


Jerome

 

[Mike Davis]

Be sure it is dry like for a week or more then go ahead and top coat it.

 

[Jerome B]

Be sure it is dry like for a week or more then go ahead and top coat it.

Cool. Wow I didn't realize that It would take so long. It makes me wonder about the pigment/stain that I want to use to recreate my 1850's red wash. This stuff would be a great vehicle for a stain to be followed by a varnish, except it takes so long between steps. I was sure that the stain would have had to be water based, but it could be oil based, but wow the wait time between steps is a while. I need to go back and look at Day's production output at the end of his career and see if he could have waited that long.

Jerome

 

[Mike Davis]

Probably not, you can recoat oil over oil after a day. But you said Waterlox, so I think more time is needed to let the oil dry off before the water based varnish is applied.

If i were using a long oil varnish over danish oil and an oil stain I would wait a day between coats unless the older coat still felt tacky. Since they are all basically the same thing they will blend and meld together.


I think Waterlux, lacquer or polyurethane would create more of a vapor barrier that could blister as the oil cured.




Seems that the finishing time would not necessarily interfere with production if there was enough space available to let the finished piece sit while other work was being done on the next piece.

 

[Gofor]

Watco Danish Oil can says you can overcoat with poly after 72 hours (I am assuming oil-based poly). However, Behlens Rock Hard table top finish worked very well for me (I did not use it over stain, tho,) It is not a poly. Its a short oil phenolic varnish.

Go

 

[Howard Acheson]

To clear up or re-state a couple of points. Watco--or any other oil/varnish mixture--can be over coated with an oil based film finish within 24-48 hours. While the Watco really takes longer than that to fully cure, an oil based finish is oxygen porous enough that it can continue to cure with the oil based over coat. Watco will also continue to cure with a single coat of shellac. Shellac creates a more oxygen impervious film than oil based varnish. If shellac is going to be he final finish, and you apply more coats, it is best to allow the Watco to dry/cure for 4-5 days. It takes the linseed oil in Watco that long to dry/cure and it needs oxygen to do that properly. Similarly, 4-5 days is recommended if you are over coating with a waterborne b finish but for a different reason. Waterborne acrylic finishes have less aggressive adherence characteristics. Therefore, applying a waterborne finish before the underlying finish is fully cured can lead to adherence problems.

Finally, Waterlox Original is not a waterborne product despite the confusion related to its name. Waterlox Original is a fairly standard non-poly oil based varnish. It's made from phenolic resin and tung oil so it's a hard varnish with excellent water resistant qualities. Behlen's Rockhard is also a phenolic resin varnish that produces a very durable finish.

 

[Jerome B]

sheesh this oil based stuff seems pretty complicated. I'm about ready to go running back to my shellac, but I want to come up with combination that mimics what was used in 1850 so onward I brush.


J

 

[Travis Porter]

sheesh this oil based stuff seems pretty complicated. I'm about ready to go running back to my shellac, but I want to come up with combination that mimics what was used in 1850 so onward I brush.


J

No pun intended, right>:wink_smil

 

[Gofor]

I can only recommend the Behlens (have not used Waterlox). I had a few visitors over this week-end who saw the table I built that was coated with the Behlens (pics of the table in my gallery, and pics of the visitors in the Goldsboro Shop Crawl gallery). Most noted the amount of shrinkage by referencing the breadboard end (it was flush when coated and is now a good 1/8" in from each side). No finish distortion , cracking or damage after over a year.

Go

Oil based isn't more complicated, just slower. When you get to my age, that can be a good thing:rolf:

 

[MrAudio815]

I can only recommend the Behlens (have not used Waterlox). I had a few visitors over this week-end who saw the table I built that was coated with the Behlens (pics of the table in my gallery, and pics of the visitors in the Goldsboro Shop Crawl gallery). Most noted the amount of shrinkage by referencing the breadboard end (it was flush when coated and is now a good 1/8" in from each side). No finish distortion , cracking or damage after over a year.

Go

Oil based isn't more complicated, just slower. When you get to my age, that can be a good thing:rolf:

Mark's Table is Very beautiful. And yes it did shrink quite a bit since I seen it last year, amazing how wood works.

There is some great advice given and I can't wait to see your Pictures of your table.

I used Rocklers WunderCote on my maple butcher block table, but thats a water based finish. I made it in summer 2006.

 

[Howard Acheson]

>>> I want to come up with combination that mimics what was used in 1850

Stay with the shellac then. You won't have to "mimic" as shellac is the most traditional of the modern finishes. It came into general use in the US and Europe in the early 1800's replacing linseed oil and wax.