NFIP wood

[Don Hiatt]

the last two years I have been turning turning Northfolk island pine , and been soaking them in linseed oil and minerals spirits , the issue is that the knots will not dry or keep a finish on them what should I do

 

[john lucas]

Never turned NIP but when I have knots that bleed or won't take finish I use a coat or two of shellac to seal.them.

 

[Don Hiatt]

Never turned NIP but when I have knots that bleed or won't take finish I use a coat or two of shellac to seal.them.

So apply shellac to knots only then I can apply more finish over shellac

 

[Doug Freeman]

Shellac is a great sealer for resin like this case but it may not look that great on the finished piece. Im wondering whether its the pine resin seeping or is it the linseed oil. I suspect you are soaking for translucence, which Ive never done and dont know much about, so I will approach from a finishing perspective that may not apply to translucence.

If using raw linseed oil it takes years to dry. If using blo, you could add additional japan drier so it dries faster. I also wonder if a varnish would be better. A thinned poly may achieve the same look but provide more stabilization of the wood and a better finish. Either would not require shellac unless it is resin seeping out. If so adding a little japan drier may stop the resin seeping.

 

[Dennis J Gooding]

I would agree with Doug. Also, note that some "drying" oils, for example walnut oil, need sunlight to cure at any reasonable rate. (Apparently UV light is not needed since light passed through a window will do the trick.) Also you might consider the old standby of equal parts varnish, boiled linseed oil and thinner for a wipe-on wipe-off penetrating finish. (Poly works fine for the varnish component.)

 

[Don Wattenhofer]

I have been doing translucent pieces for many years and have settled on lacquer sprayed on using a small gravity feed Harbor Freight spray gun. The only NFIP up here in the lakes country is potted. I have used eastern white pine, birch, black cherry, buckthorn, white & red oak and anything else I come across and use lacquer on all of them. The walls are usually no more than 1/16th inch thick and will allow light to pass thru. The first pic is red oak about 8" diameter and the second is white pine branch wood about 3" diameter.

 

[Dennis J Gooding]

I have been doing translucent pieces for many years and have settled on lacquer sprayed on using a small gravity feed Harbor Freight spray gun. ..... View attachment 29930

Nice pieces, Don. I too use lacquer a lot, but generally have not particularly tried for translucence. I wonder if a wipe-on/wipe-off application of highly thinned lacquer before the regular coats would increase the transluscence.

 

[Don Wattenhofer]

Nice pieces, Don. I too use lacquer a lot, but generally have not particularly tried for translucence. I wonder if a wipe-on/wipe-off application of highly thinned lacquer before the regular coats would increase the translucence.

I think the translucence has more to do with the thickness of the wood, many times when I spray the inside first the lacquer soaks thru to the outside especially in ring porous woods like oak.

 

[hockenbery]

Thin walls are needed for translucency
The fiber optic effect enhances the translucence.

Most readers will have used a light to turn green wood thin or seen it used in demos.
Water in wet wood gives the light a path through the wood.
These green turning lose much of their translucence when the wood dries.

The various treatments of NIP use oils to make fiber optic paths through the wood to enhance the translucence.
We have a NIP bowl by Gerhart Schwanke with 1/4” thick walls that is translucent.

 

[Emiliano Achaval]

the last two years I have been turning turning Northfolk island pine , and been soaking them in linseed oil and minerals spirits , the issue is that the knots will not dry or keep a finish on them what should I do

Take a look at Ron Kent's web site: https://www.ronkent.com/techniques.php Ron was the master of Cook Pone turning, and some NIP. 90 % of pines in Hawaii are Cook. The mix we use is 5 to 1 BLO and mineral spirits. I have never seen knots not drying.

 

[Dan Stevenson]

I turn NIP almost exclusively, and do lots of translucent work with it. I haven't encountered problems with knots NOT drying out, but since the density difference between them and the heartwood - they do dry differently. There seems to be some sapwood around each knot that surrounds it as it travels outward from the pith so you have a third density - all 3 of which dry and shrink at different rates - but all eventually do dry out. I turn green to thinness of +/- 3/16" with lights behind to help guide me and do the last cuts with the laser (But I too have done translucent pieces 1/4" thick. Kelly Dunn told me that the more angled the forms are across the grain, the better the light allows for translucence. My own study bears this out. Very often I'll use CA glue on the outside form around the knots to keep them together and frankly - to keep them from popping out altogether which has happened unfortunately many times. After turning thin I watch those knots carefully while the form dries over the next 2 weeks and in that time the contractions will happen. Often I fill those shrinkage areas with either paduak dust(for red) NIP dust (for whitish) or some kind of colored crushed stone powders mostly set in with thin CA glue and gently hand sanded flat. As for the knots weeping once they come out of the soak (which I use 2 parts Mineral Spirits to 1 part BLO & 12-16 hour rotations) after lightly wet sanding the piece while dripping I wipe it down dry with paper towels. Then - 10 minutes later - wipe down those knots again as you'll see they are still wetted while the greater form isn't. During the soak/dry rotations, I dry the pieces in my shop with a fan blowing on them. After the process, I let the piece dry completely for a couple of weeks then spray lacquer and wheel buff. Most of the pieces feel like glass when finished. You really have to mind the knots from start to finish they're tricky at times.I hope this helps Don.

 

[Mike Johnson]

Another option might be pulling a vacuum on the wood blank to extract all of the moisture and sap from the piece. Some sawmills have adopted the newer style vacuum kilns that simplify the drying process of woods. These newer systems can accept various moisture content and species of wood at the same time and come out of the kiln at the same level of moisture content.

 

[Don Wattenhofer]

Thin walls are needed for translucency
The fiber optic effect enhances the translucence.

Most readers will have used a light to turn green wood thin or seen it used in demos.
Water in wet wood gives the light a path through the wood.
These green turning lose much of their translucence when the wood dries.

The various treatments of NIP use oils to make fiber optic paths through the wood to enhance the translucence.
We have a NIP bowl by Gerhart Schwanke with 1/4” thick walls that is translucent.

1/4" is not thin

 

[Don Wattenhofer]

Dan talked about knots falling out and ways to prevent it. I have never worried about keeping knots but I think I may have some insight into why some fall out. The trees in the forest start out covered with branches and as they grow and reach for the sun the lower branches die off and eventually get covered up. If when turning you encounter a knot from a dead limb it will likely be loose unless you can turn down to the point where the limb was still live.

 

[Dan Stevenson]

I salvage the NIP here locally in Tampa since folks use them as ornamentals. The dead limbs are often the lower branches that have been pruned off so you can mow under them without getting a face full of pine. When there's just 1/8" of a dead knot spinning at 750 - sometimes they pop out and go who knows where in the shop. Sometimes you notice and can find them. Other times I've carefully replaced dead limbs (which don't allow transparency btw) with nice knots which do glow.

 

[hockenbery]

1/4" is not thin

My point exactly! It is that thick and with the absorbed oil shows translucence

I have some oak goblets that showed bright yellow when turned wet.
A 1/16” thick cup wall and they are not what I would call translucent when dry.
A bright light inside would show a little but my idea of translucent is to glow bright color with an overheat light.

 

[Don Hiatt]

Thanks to everyone the process that I have been using with the NFIP is to turn to 1/2 thick soak in 50% blo and mineral spirits (24) hr then after drying for a couple days, finish turning (3/16) wall, wet sanding with same blo/ min spirits , after dry , wet sand again with equal parts blo-mineral spirit and polyurethane, it sounds like I need to change to a higher mineral spirits in the mix. I have been having good luck with translucency, then when they do dry I buff them , sure are a great eye catching piece any added advice is appropriate

 

[Emiliano Achaval]

1/4" is not thin

Only a woodturner's opinion.