Top-coating BLO

[millwab]

Scrollers,
I was thinking about trying BLO for the first time. I've read somewhere in a thread here that (at least) some use BLO to "pop" the grain and then top-coat with a lacquer or some other finish. After reading the BLO label, I don't understand the need for the top-coating. It sounds like the BLO would be complete in and of itself. Could someone explain why the top-coat?

Also, if using BLO on (eg) BB, maple or some other "white" wood, does it tint it any or will the wood stay white? If there is some yellowing, what would you recommend to use instead to keep the white shining through?

Bruce

[MacS]

B L O- boiled linseed oil

Bruce,

Yes, some people do use BLO to "pop the grain" (there are other ways of poping the grain)

And, you can completely finish with BLO alone, one of the problem is dries to a low sheen, two its a very thin film, three it takes a lot of applications, and forth, the yellowing is not conducive on many woods, on darker woods like walnut, mahogany, ebony it will enhance the finish..

Acrylic lacquers, CAB coatings, and all water base coatings all of these are "water clear coatings" they are non yellowing, you can use clear shellac.

[millwab]

Thanx Mac. This project is going to be a 'portrait' cutting so I wasn't too worried about the sheen or how heavy a coating was on it. I was more concerned this time about the yellowing since I'd be using a light colored wood. My next project, though, is going to be a clock. I was hoping to figure out the finishing before the clock comes up in the queue. I'm not sure yet, but it will probably be cherry with maple accents and I'll want good grain appearance as well as durability.

Bruce

[MacS]

Blo

Bruce,

BLO is a "reactive coating", which means that each application of BLO that you apply to the wood it becomes a thin layer, each coating will lay on top of the proceding coating. Varnish and Polyurethane are reactive coatings.
Both of these solvent coatings are amber in color, whereas, their Water Base coatings are water clear.

Shellac, Nitocellulose, Acrylic, CAB Lacquer are "evaportive coatings," these coatings dissolve into each application, so you end up with one layer regardless of how many applications you apply.

Nitrocellulose is amber in color. While the others are water clear.

Some of the amber coatings actually warm up the wood finish, while the water clear coatings lose that feature.

[Mick Walker]

Bruce, BLO is not a protective coating it is an oil that soaks into the wood. You should apply a coating over it and it will turn the wood an amber color. Make sure the BLO is dry as it takes a few days before you can apply protective coats over it. I would try it on a scrap piece first.
My 2¢ worth.

[MacS]

Protective Coating

Mick,

BLO is a "drying oil", it is not the same as Linseed Oil.

A metallic drier is added to the Linseed oil this speeds up the drying time of the oil, thats why they call it a drying oil, the metallic driers actually acts as a catalyst, speeding up and hardening the oil.

Thats why, if air gets into the drying oil containers it will cause the top of the drying oil to skim over.

Almost, ever one of the "OIL FINISHES" that are sold, contain a drying oil from the popular Watco, and the Danish Oil to the Teak Oil, even those that are know as "penetrating oils" are basically either Tung Oil or BLO with a colorant or resins added.

[millwab]

In summary

So Mac, if I'm understanding this correctly any oil I would use would be to bring out the color/grain characteristics of the wood and a coating over that would be for 'protection.' Is that a fair summary?

Would the coatings bring out the wood characteristics without the oil?

BTW, 'CAB' coatings is not a familiar term to me. What does CAB stand for?

Bruce

[MacS]

Drying oils

Bruce,

Yes, but not all drying oils are as dark in color, BLO is darker in color then Tung Oil, some Tung Oils from South America are lighter in color then Tung Oils from China. There are other drying oils besides these two. I don't want to make a big thing out of this, but 100% Tung Oil is approved to be used on salad bowls, cutting boards, ect. wherwas BLO is not, on the other hand the BLO dries faster.

As far as "protection" goes, it would depend on what you are going to use the "oil" on, if you were doing a wall plaque any of the drying oils would do as it would not really need a lot of protection, the only reasons it would be used is for "color" and to "seal the wood" so any dust and dirt wont enter it. Now, on the other side, if you was going to finish a desk or a kitchen table, you would want a more durable and chemical resistent coating. You should consider what coating would be best on this piece, how much use and abuse will it have to take.

Even, the coatings with an amber caste would not be as affective as the oil, because coatings lay on the surface of the wood, whereas, the drying oils are allowed to soak into the wood before they are wiped off and then they are allowed to dry, so they will penetrate into the wood and remain there.

What does CAB stand for?

Cellulose/Acetate/Butyrate, its a "water clear coating", its not really new, I think, it may have been the first water clear coating used on furniture.
It fell out of "grace" for many years, but then it made a come back, after it was modified, it is also, sold in colored coatings, it is popular in shades of white because it don't yellow.

Class dismissed...

[pete00]

BLO and CA glue is a popular long lasting finish for pens on my other home. I perfer a shallac type finish.

A video was just put up on the instructions page.

take a look if so inclined......pete

http://www.penturners.org/forum/topic.asp?TOPIC_ID=17155

[MacS]

Tung Oil vs Acrylic Lacquer

Bruce,

The top woods are Baltic Beech, the left panel was coated with only Tung Oil, the right BB panel was coated over with "only" Acrylic water clear lacquer.

The bottom left panel is Burr Oak, it was coated over with only Tung Oil, the right panel was sprayed with only Acrylic water clear lacquer.

Bruce, you will find that on other woods you may get different results, that is why you should always make up complete start to finish samples.