How much Rockhard per sq foot?

[SubGuy]

I got a commission project and I am ordering finish. Does anyone know how much Behlen's Rockhard will cover? I am planning 3-5 coats but it would be nice to know how much in one coat roughly. Thanks in advance.

 

[Jeff]

About 125 sq ft/qt.

http://www.shellac.net/rockhard_table_top_urethane_varnish.html

 

[SubGuy]

Thanks for that. I actually looked at that while I was writing this, but I have found that advertised coverage amounts were generally very over or understated in most cases. Additionally, I was thinking it was only for one coat and was probably not under consideration of coating raw wood. So I apologize for being unclear. So can anyone attest to this figure they give? I do understand that different woods will use different amounts and I also understand that temperature and application thickness and method is a variable as well. Thanks.

About 125 sq ft/qt.

http://www.shellac.net/rockhard_table_top_urethane_varnish.html

 

[McRabbet]

Zach,

I've used Behlen's Rock Hard Varnish on 3 projects and the coverage is pretty close to what is on that description sheet. If you are planning to apply it onto an open pore wood, then I'd recommend using Pore-O-Pac (untinted) as they recommend (I used it on some African Mahogany with excellent results). I cut it 50:50 with Behlen's Reducer (better quality than big box mineral spirits) for a sealer coat and applied it with a very high quality bristle brush (badger is the best) in thin strokes with light touch. Like any short-oil varnish, it will bubble if you are too aggressive with those brush strokes -- I keep the brush nearly vertical and never shake the varnish. I normally did the sealer coat and two second coats with very light 320 grit sanding between coats. You must by absolutely dust free or you'll be frustrated with dust bunnies. Ditto bubbles.

Here are some examples on African Mahogany (my Wine Cellar commission) and Bubinga (Countertop commission) (Many more pics in my Gallery). The 3rd project was my first usage -- I took the finish off a maple veneer kitchen table, stained the maple with Cherry SolarLux and applied 3 coats as above. That was done 10 years ago and water still stands in beads on the finish. Hope this helps.

​

 

[Gofor]

The other thing about Rockhard is that it does not keep well after the can is opened. It may do better if you have some Bloxygen to spray into the can when resealing. So, you may not want to order more than you need, even if the gallon size is a lot cheaper per pt than the quart size. That said, it is an excellent coating, my favorite for top surfaces.

It sets up pretty quickly after exposure to oxygen, so if doing something as large as a table top, tip out slowly with the brush vertical about every 2nd row of application to get the bubbles out. Otherwise it will start pulling on the brush if you wait too long. It worked best for me by applying with a slower brush speed tthan minwax poly. That said, it levels out beautifully.

Go

 

[McRabbet]

Mark,

Thanks for the mention of Bloxygen -- I used it every time I finished each coat on those projects in order to avoid any skim on top of the balance in the quart cans. +1 on your brushing advice.

 

[SubGuy]

One of the woods on one of the 5 pieces is ring-porous. If I use the Pore-O-Pac, will it cause any color change in the wood, or could I get away with a couple coats of shellac to seal the grain? And how far will one quart go?

 

[McRabbet]

I found that the untinted Pore-o-Pac left noticeable white dots where pores were filled, but they disappeared completely when I put the first coat over it (that reduced coat I mentioned above). Here are more details. Behlen also has a good video on grain fillers that may give you more info (click on the YouTube logo to see it full screen). I did use their reducer and the squeegee they show. As you can see from the video, you can also stain the filler. A quart goes a long way. I have not used their water-based filler.

 

[SubGuy]

Well I know what I need to get for sure. Woodcraft, here I come.

 

[SubGuy]

Zach,

I've used Behlen's Rock Hard Varnish on 3 projects and the coverage is pretty close to what is on that description sheet. If you are planning to apply it onto an open pore wood, then I'd recommend using Pore-O-Pac (untinted) as they recommend (I used it on some African Mahogany with excellent results). I cut it 50:50 with Behlen's Reducer (better quality than big box mineral spirits) for a sealer coat and applied it with a very high quality bristle brush (badger is the best) in thin strokes with light touch. Like any short-oil varnish, it will bubble if you are too aggressive with those brush strokes -- I keep the brush nearly vertical and never shake the varnish. I normally did the sealer coat and two second coats with very light 320 grit sanding between coats. You must by absolutely dust free or you'll be frustrated with dust bunnies. Ditto bubbles.

Here are some examples on African Mahogany (my Wine Cellar commission) and Bubinga (Countertop commission) (Many more pics in my Gallery). The 3rd project was my first usage -- I took the finish off a maple veneer kitchen table, stained the maple with Cherry SolarLux and applied 3 coats as above. That was done 10 years ago and water still stands in beads on the finish. Hope this helps.

​

Behlen discontinued the rock hard reducer. I bought naphtha. It appears to be one of the main volitiles in the rock hard. Any objections?

 

[McRabbet]

Nope, I'd just follow their guidance. I didn't mention it but I used the glossy version and for one project (the second picture), I buffed out the top starting from 320 to finishing with 1400 grit with an ROS to achieve a satin finish.

Rob

 

[SubGuy]

I will. I bought satin, because that's what the customer wanted and it would be quicker to go straight to it rather than rub it down to satin. I don't think he will be as picky of the finish as I will. I am obsessive over finish, if there is a defect, I lose my mind trying to make it disappear. Thanks again Rob.:icon_thum

Nope, I'd just follow their guidance. I didn't mention it but I used the glossy version and for one project (the second picture), I buffed out the top starting from 320 to finishing with 1400 grit with an ROS to achieve a satin finish.

Rob