Varnish over Oil

[Bonecarver]

I am ready to finish a honduras mohagony piano bench and would like to know if I finish it with a danish oil hand rub can I use a hvlp sprayer to spray Behelen Rockhard table top varnish over the top of it? So in reality I guess it is two questions. Can I use varnish over oil and can I spray on Varnish.

BC

 

[daclgr]

I have never used varnish over oil. I have however used arm-r-seal and the one thing I will caution you on is to make sure that the oil is good and dry. I beleave that they suggest 72hrs I would give it longer, I will wait a week sometimes before I start the top coat. I have tried 72 hrs and then the top coat would not dry for several days, or maybe just one section was a little wet.

 

[Howard Acheson]

If your intent is to use an oil based varnish as your final finish, there is no need to first apply a "Danish Oil". Danish oil is almost totally linseed oil. The linseed oil is what "pops" the grain. You can just apply a heavy coat of boiled linseed oil, let it set for 30 minutes and then wipe it totally dry. Let it dry for 48 hours and then apply your clear coat final finish.

Spraying oil based finishes is problematic. They dry so slowly that the overspray is a liquid. It gets on everything in the shop and forms a crust. So, unless you have a good spray booth to capture the overspray or can spray outdoors, you will have a problem. You also need the proper respirator to protect your lungs.

 

[Trog777]

You can just apply a heavy coat of boiled linseed oil, let it set for 30 minutes and then wipe it totally dry. Let it dry for 48 hours and then apply your clear coat final finish.

Make sure if you're using a water based clear coat over BLO, apply a barrier coat between, such as shellac.

 

[Howard Acheson]

>> Make sure if you're using a water based clear coat over BLO, apply a barrier coat between, such as shellac.

That's not really necessary if you let the BLO dry for 4-5 days.

If a shellac were used and the finisher were going to use a waterborne finish, then dewaxed shellac would be required.

 

[John Reeves]

I have done this with great success and did not need any barrier between the BLO and the ROCK HARD VARNISH. Make sure that you need the oil. As Howard said its only purpose in what you are doing will be to enhance the grain.

I used a brush for the Behenlen because i did not want to suffer the VOC's. It takes some time to dry then cure but it gets very hard. It will have an amber tint to it so plan for that color. You will need to scuff the Behenlen as it does not burn in very well unlike other solvent based varnishes. I used three coats and got a very glossy and smooth surface Behenlen does have very good flow out qualities but you will have to give it a little more time to dry and cure.

 

[Trog777]

If a shellac were used and the finisher were going to use a waterborne finish, then dewaxed shellac would be required.

Yep, should have mentioned it should be dewaxed shellac. Never tried the wait 4-5 days thing. How do you know it's ready to be topcoated? Odor?

 

[Bonecarver]

Thanks guys maybe the varnish isn't the way to go. The oil really "popped" the grain out and I certianly don't want to ruin the look with an amber tint on top of Mahogany. Thanks for the input!

BC

 

[BillPappas]

BC,

I made a bedroom set out of mahogany and I used BLO with Behlens Rockhard Varnish over the top of the BLO. I thinned the varnish with mineral spirits then padded it on after the BLO cured for about 3 days. I rub down the BLO every 4 hours or so the first day and then a couple more times each day until it cures...this removes any bleed out from the BLO. I usually put on about 4 coats of the thinned varnish. I did not want a glossy finish so my final (5th) coat of varnish was actually minwax satin. Final step after a week or so was a rub down with a brown paper bag to knock off the dust nibs.

Here is a picture of the dresser top with this finish....

Regards,

Bill