Was I too impatient?

[Eric Gourieux]

I applied several coats of dewaxed shellac and then began spraying WTF using the JKWTFBDAR technique. I've had good luck with this technique on smaller hollow forms, but this piece may be too big. It looks like one of the coats did not adhere properly. I'm not sure how many coats I had applied by this time, but I know I applied several coats, sanded flat, reapplied several and sanded again. Overnight, these splits developed. Any suggestions as to what may have happened? I left the vase on the lathe in my heated shop, so I don't think temp had anything to do with it. I have a couple of "shop cats" and thought that one of them scratched on the vase when I first saw it.

Walnut vase 18" x 8". I don't have any pics of the whole vase, yet. Final pics to follow when complete.

BTW, JKWTFBDAR = "John Keeton Woodturners Finish Blow Dry And Repeat"


IMG_7294.jpgIMG_7292.jpgIMG_7293.jpg

[Paul Williams]

This sounds like a dumb question, but are those cracks in the finish or in the wood. I have a batch of walnut that is prone to cracks like that the day after turning., with or without finish. Number 3 especially looks like a crack in the wood, but that could be just the difference in viewing a photo vs real life.

[James Combs]

How dry was the blank. Looks like drying cracks to me.

[Roger Chandler]

You don't have a finish problem........you have a drying problem! I had a similar issue with a recent hollow form and had to turn away those cracks...........then control the rest of the drying ..........I got lucky! I think if you had soaked in DNA and then allowed to dry slowly before final sanding and finish, you may have been okay............can't guarantee that result however, but it is worth a try for sure!

[Eric Gourieux]

Thanks for the replies. The wood is dry. I rough-turned, Anchor Sealed, and then dried in my "kiln". The cracks are not in the wood. I wish they were. It would make more sense to me that way. The deeper coats of WTF are intact.

[Reed Gray]

I think the old saying about 'if it cracks, you dried it too fast' applies here. Surface finishes, if built up thick and fast have to cure as well, and when curing they shrink. Too thick, and too fast and it will crack. Almost reminds me of putting medium CA glue around a threaded nut I recessed into a waste block, maybe 1/2 inch deep. After drying for 24 hours, I was turning and getting CA spray. I put them over the shop heater to quicken the drying, and the glue recessed way down in, and was honey combed. I don't think there is any type of epoxy or finish that does not shrink as it cures. Sanding off or down, then recoating is probably the best option.

robo hippy

[Richard Coers]

Thanks for the replies. The wood is dry. I rough-turned, Anchor Sealed, and then dried in my "kiln". The cracks are not in the wood. I wish they were. It would make more sense to me that way. The deeper coats of WTF are intact.

You wish the wood was cracked? Strip the finish and start over. If the cracks are in the finish like you say, the refinish will make it perfect. Can't imagine those are not in the wood based on the pictures. Another reminder, just because you can touch the finish, it doesn't mean it was cured. Give it time! You don't mention how long you waited between coats, nor the age of the shellac. Old shellac can cause trouble.

[Dennis Nagle]

There may be some sort of oil or wax left on the wood.

[John Keeton]

BTW, JKWTFBDAR = "John Keeton Woodturners Finish Blow Dry And Repeat"

Eric, I am not sure of the derivation of this concept. While I have used WTF, though not so much recently, and have applied multiple coats within minutes on a warm, dry day, I have never used a blow dryer or assisted the drying in any way beyond ambient conditions. Perhaps your acronym is simply a joking reference to the rapid application process (and, it probably is), but I didn't want any viewers to get the wrong impression.

My guess is that the ambient conditions were not conducive to a rapid application of multiple coats. Even with the recent cold weather, the relative humidity has been high, and I suspect it is the same in your area. I have had the best success with this type of quick finish process standing outside, in the sun, on a 85-90* day. I don't think I would attempt it in conditions other than that, and would allow more time between coats.

The problem now is that WTF is difficult to remove without using a citrus stripper. The good news is that process goes fairly well and you should be able to save the piece.

One other note - I have found the shelf life of WTF to be quite limited, and for that reason alone, I have drifted away from it. On a large piece, it is difficult to use and I prefer WOP for a film finish.

I hope you are able to recover the piece.

[Eric Gourieux]

John, MY APOLOGIES! I didn't mean to misrepresent your process. I must have confused the "blow drier" concept with yours. I must say that I've had good success with it in the past on smaller pieces. I have also noticed the short shelf life of WTF. I was attributing it to user error - not sealing the can well enough. That still may be part of my problem although I do seal it up as well as I can.

I was able to sand down to get past the splits and have applied a few more coats. Once I finish it, I'll post final pics. I will be taking my time this time around.

[Faust M. Ruggiero]

Eric,
I am willing to bet you let the shellac soak into the wood the first couple coats. That causes the wood to swell then rapidly shrink. The dried shellac binds the fibers enough that as the piece shrinks with the evaporation of the alcohol the piece has no choice but to crack. The layers of shellac must be light and built up with several coats.
faust

[Doug Herzberg]

Thanks for the replies. The wood is dry. I rough-turned, Anchor Sealed, and then dried in my "kiln". The cracks are not in the wood. I wish they were. It would make more sense to me that way. The deeper coats of WTF are intact.

What an illusion! I looked again and I see it now. I was never sold on WTF, despite the excellent results JK posted. I bought one can and opened it once to fill a plastic squirt bottle. A year later, I am still using the product from the squirt bottle with no noticeable degradation in the resulting finish, not that it was ever as good as the results I saw others getting. I guess I'm with John - strip it and start adding back coats without the blow dryer. I might test the finish on some scrap first in case it has gone bad.