Plastic Wrap to Control Drying while Hollowing

[Marty Tippin]

(I guess great minds think alike -- I was watching Robo Hippy's bandsaw video in another browser window while composing this post and (I swear!) just about the time I was ready to hit the Submit button, he stole my idea in his video! So if you've just watched his video, you'll think I'm taking credit for his idea... )

I was working on my second attempt at a cremation urn yesterday and needed a way to slow down the drying of the exterior while hollowing the inside. I've previously used plastic grocery sacks to wrap a piece when I'm going to be away from the lathe for a while, but I didn't think that would work well for a piece that I'm actively working on - I use a laser-guided hollowing system and need to accurately see where the laser is hitting the piece. I tried (briefly) to use plastic packing tape (the wide, clear stuff) but didn't like how it went on as it left bumps and ridges that would distort the laser. Then it occurred to me that plastic stretch wrap (the kind that is used to secure boxes on pallets for shipping, etc.) might work, and I happened to have a partial roll leftover from our move to the new house a couple of years ago.

So I wrapped the outside of the urn in the stretch wrap, going all the way around the top end as well. I trimmed the excess from the end and added several cross-ways strips of packing tape, then carefully cut out a hole about 1/2" bigger than I intended the opening to be, and wrapped a few strips of tape around the base of the urn and in the middle. Unfortunately, I didn't get any photos, but hopefully you can visualize what I'm desribing.

This ended up working wonderfully as I hollowed - I could see moisture starting to collect inside the plastic wrap but it wasn't able to escape, keeping the outside of the urn nice and wet as I hollowed the inside. The wrap conformed to the shape of the urn nicely and the laser was easy to see. And the reinforcement around the opening held it all in place through 2+ hours of hollowing. Plus, I was interrupted for a few hours to watch the KC Royals clinch the American League championship and didn't have to worry about covering the piece when I walked away -- all I did was stuff a plastic grocery sack in the opening to keep the inside from drying out.

I don't know if regular "Saran" type kitchen wrap would work or not - the stuff I have came from a moving supply company and is a lot heavier than the kitchen wrap and is extremely stretchy, allowing you to make it conform to whatever shape you're trying to wrap.

Anyway, I wanted to share in case this is "new" to anyone else and might be helpful.

[Peter Blair]

Marty, I too use shrink wrap on my turnings. Especially while on the lathe when I need to take a break overnight or so. I have also tried, with some success to wrap the outside of a roughed out piece instead of using a wax sealer. I also have found that sometimes when I turn thin or porous wood it helps to hold a vacuum when I reverse to finish the bottom. Thanks to Reed I now will use it instead of my second freezer when I need to keep a rough out for a a few days before getting to it.

[Jerry Rhoads]

Beats the hheck out of the plastic bags. Thanks for posting this Marty

Jerry

[Reed Gray]

Great minds think alike Marty. Glad to see the Royals advance. I grew up in St. Joe.

robo hippy

[robert baccus]

Plastic wrap works well for short periods but also for totally drying vases and hollow forms. Two layers and leave the opening open seems to season a roughed out piece very well.

[Mike Null]

I buy that shrink wrap in 6" rolls from Uline. It lasts a long time.

[robert baccus]

HF is another source of 6" rolls.

[Ronald Campbell]

This week I have finished 4 pieces in the 22-23 inch range. They were all wrapped with stretch wrap while I hollowed them. It takes me too long to turn and then hollow to do it in one day. I will work 4 hours on turning and shaping and then the next day I will hollow. The stretch wrap allows me to keep the moisture in the wood and control the shape to finish

[Thom Sturgill]

It also works well to hold forms with voids that might make the piece want to fly apart while hollowing, and club members have used it to hold a piece while glue cured to fill a crack. It can apparently develop quite a bit of compression.

[Lee Watermann]

Does anyone actually heat it to shrink it or just stretch it on?

[Reed Gray]

This type of film is for stretching, not heating. If you heat it, most likely it will melt into a sticky mess. You can stretch it to the point where it will conform to just about any surface. I have used it to glue broken bowls back together as well.

robo hippy

[Robert Henrickson]

Kitchen plastic wrap has worked fine for me. Its width can be a drawback in some cases, but it is always at hand. I've also used it sometimes as a clamp when gluing awkward shapes.

[terry richards]

I too have had success with plastic wrap. "Saran" wrap works well, but is difficult to re-use. I use the cheap plastic painters' tarps - cut about 8" off the end while they are still folded. They conform reasonably well, and can be used several times. I leave the piece fully wrapped, except for the vase opening, until it is almost dry. Then I put a sealer on the outside only, leaving the inside raw. I weigh it with the plastic wrap included, so I can tell when it stops losing water.

I also have had excellent success by filling the hollow form with oil-dry, the kind you get at the auto parts store. By all means, do NOT use kitty litter. Kitty litter looks the same but contains polymers to encourage clumping. You don't want your form choked up with kitty clods. Just get the cheap stuff - pure fuller's earth, no additives. I pour it out and replace it every few days. It sucks the moisture from the outside through to the inside walls. You will see moisture condensed on the inside of the plastic wrap at the beginning, but it goes away in a week or so. It is migrating back into the piece and through the interior walls.

The key is to keep - as long as possible - the moisture equal on the inside and the outside of the form.

You can bake the used oil -dry in the oven on a cookie sheet at about 200 degrees for an hour or so, or you can pour it out on a black trash bag on the hot sidewalk in summer. It dries out nicely, and is good as new.