Does anyone put a finish on the inside of a hollow form?

[Grey Darrah]

I was putting a finish on the outside of a shorter, side grain vessel (flying saucer-ish) and noticed that with a shorter vessel of 4 to 6 inches deep, it's pretty easy to see the dry, unfinished wood at the inside bottom. With taller end grain forms, it's dark enough down in there that it's less noticeable.

So is leaving the inside unfinished what most do? Or if you do finish it, how do you get it done? It's pretty hard to get down in there with a 1 /14 inch opening.

Thanks,
Grey

 

[Mark Wollschlager]

For me it depends on the opening size and what I am after.
Normally my 'closed ' hollowforms do not get finish on the inside.
Sometimes dye or finish will wick through on the endgrain and leave stains on the inside.
If I think that the inner surface is ugly, I might put black gesso inside.

I think that finish on the inside takes too long to cure if there is no airflow.
When I have used an immersion technique to apply finish I have found this to be true.
My more open hollowforms always gets finished on the inside.

 

[Breck Whitworth]

The few times I've done hollow forms the hole was large enough for people to see the inside so I poured linseed oil into it and rolled it around until the inside was covered. The only draw back is depending on the wood and wall thickness you could get a bleed through that might be visible using a type of oil. You could probably use a lacquer type finish that would dry quick enough to prevent that from happening. Or if you have the skills make the opening so small no one can see inside! Here is an example of bleed through at the base (using linseed oil) that I tried to make it look like I planned it. (didn't work to well)

 

[Odie]

Here is an example of bleed through at the base (using linseed oil) that I tried to make it look like I planned it. (didn't work to well)

To the contrary, Breck......If you hadn't mentioned your disappointment, I'd have never known it was something that you weren't happy with!

You see things, as the maker.....entirely different than an observer does.....

-----odie-----

 

[hockenbery]

I don’t sand the interior of hollow forms except maybe the bottom middle if tool marks are showing.
What I do is use a teardrop scraper to get a smooth looking surface. Most HF I apply one coat of watco to the inside after the outside is finished with 3-6 coats of Waterlox just wipe on with a cloth in a forceps just tomwet the surface. Once the outside is finished no blead through and one coat dries to soft matte finish.

The form below is one that showed a lot of interior. It is 13-14” diameter spalted maple Burl.
I bleached the inside to highlight it and no finish on top of the bleach.
The bleach raises the grain a bit softening any tool marks, you can spot a few.
The general appearance is a smooth surface inside. Customers love them
Sanding a form like this in my opinion is not necessary and likely to do more damage than improvement.
Sanding in not real safe for the form and would likely round over the opening edges.
The outside is finished with Waterlox, The bleached surface is not finished.

 

[Steve Doerr]

Since I dip all of my turnings, all of my hollow forms are finished on the inside. I find that by soaking them, for an hour, it helps produce a even finish on the outside of the HF. Remember end grain and cross grain absorb finish at different rates. By finishing the inside as well as the outside, both the end grain and cross grain get an even finish.

 

[Bill Boehme]

I usually do something to the interior ... it doesn't have to be especially pretty, but I sort of feel like it isn't finished until the interior is finished. I have applied black gesso to a few to make it too dark to see the interior. I have sprayed clear lacquer a couple times (lesson learned: most of the lacquer you spray in will come right back into your face). I painted the interior of one hollowform to make it look like pottery.

 

[Mike Johnson]

Most of the hollow forms I have turned over the years get a coat of sealer or finish that seals the wood. Dry wood can absorb moisture from the air so sealing the form will slow down the rate of absorption. When dry wood changes it's moisture content it will expand and contract which over time can have a negative affect on the finish and the form. Many finishes or sealers can be thinned down with compatible thinners to produce a product that can be poured into the vessel rolled around several times and poured out to leave a thin coating on the inside that will limit bleed through.

 

[hughie]

It depends on how much can be seen through the opening and or how far anybody can get their finger down inside. Either one or the other will get me finishing the inside too something similar to the outside

 

[egsiegel]

Depends on the piece and the size of the opening.
When I am able to, I apply the same finish inside and out.

 

[Gerald Lawrence]

I usually do not finish inside unless 1. the top has a wide opening, 2. Parts of the inside are easily visible. I too have used black gesso for forms I could not get smooth inside or to add dramatic effect to interior. I steer away from oil finish inside due to the slowed drying time since there is no airflow. Like others I try to sand as far as my fingers would reach when handling the HF and deeper if easily seen. Shellac is a good finish for inside as it dries quickly and can be poured in to cover hard to reach areas.

 

[William Rogers]

Larger openings i finish the same as the outside and if the opening is small I use Zinzer SealCoat (de-waxed shellac) for same reason Mike Johnson stated.

 

[John Tisdale]

Always. Wood is hygroscopic - while you can't stop absorbtion, you can slow it down.
I wipe in 300/21 Aero Marine epoxy - it penetrates a bit more than other epoxies due to low viscosity.
Slowing moisture absorption is a good thing.

 

[Grey Darrah]

John,

I checked out some of your work at the Dallas Woodturners website...absolutely beautiful work! I noticed that most of your pieces have what would call a "show finish," meaning (to me) high gloss/shine. That's where I'm trying to go with my finish work as well. Outside of sanding up into the 2000 to 4000 range, what are you using for your primary/favorite gloss finish?

Thanks so much for sharing,
Grey

Always. Wood is hygroscopic - while you can't stop absorbtion, you can slow it down.
I wipe in 300/21 Aero Marine epoxy - it penetrates a bit more than other epoxies due to low viscosity.
Slowing moisture absorption is a good thing.

 

[Bill Boehme]

John,

I checked out some of your work at the Dallas Woodturners website...absolutely beautiful work! I noticed that most of your pieces have what would call a "show finish," meaning (to me) high gloss/shine. That's where I'm trying to go with my finish work as well. Outside of sanding up into the 2000 to 4000 range, what are you using for your primary/favorite gloss finish?

Thanks so much for sharing,
Grey

HERE is a post from a while back where John Tisdale briefly describes what is needed to use his finishing process. It sort of put a damper on my interest in switching from rattle can lacquer.

 

[Breck Whitworth]

I usually do something to the interior ... it doesn't have to be especially pretty, but I sort of feel like it isn't finished until the interior is finished. I have applied black gesso to a few to make it too dark to see the interior. I have sprayed clear lacquer a couple times (lesson learned: most of the lacquer you spray in will come right back into your face). I painted the interior of one hollowform to make it look like pottery.

Great idea Bill thanks for the tip black gesso would be perfect for many hollow forms I would do.

 

[robo hippy]

Hmm, while I don't do many hollow forms, I always put finish on the inside. Main reason was to help keep wood movement equal on inside and outside. Unfinished, the wood on the inside would absorb and expel (get rid of, or???) water at a different rate than the outside. While most hollow forms are rather thin, I don't know if it is enough difference to cause any major stress...

robo hippy