Is it possible for finish to "go bad?"

[Roger Chandler]

I don't know what happened.......turned this little bowl from dunno wood.......I think it might be spalted cherry, but it had some end grain that looked a bit like sycamore .......got it from a box that another turner gave to our club a few months ago.......probably 15 years old or more......very dry.

I power sanded this and it looked really nice without a finish on it.......had to fill a couple of worm holes, but it was nice and smooth......went through grits 120,150,180,220,320 and 400 ........thought it could use some amber hues to bring out the grain so I applied two coats of antique oil....let dry, then proceeded to put a couple coats of shellac [Zinser seal coat] and let it dry, then knocked back the nibs a bit with some synthetic steel wool of a fine grit.

Put about 4 coats of Wood turners finish on..........looked awful!!! My can is down to the last 1/4 and I am wondering if the stuff is just bad now? It has a grainy, not smooth finish on it now and I need to completely resand down to the wood and start over......never had this happen before, and have used the same process with good success! Any ideas on what went wrong?

[Reed Gray]

Some finishes can go bad, but most of them just get thicker, and set up quicker if they have the chemical accelerators in them. You might be mixing too many different finishes, or possibly wax in the shellac. Not sure, as I don't use those finishes.

robo hippy

[Richard Jones]

Wood looks like hackberry and, yes, shellac can go bad. Dunno about WTF.............

More info on shelf life here: http://www.antiquerestorers.com/Articles/jeff/shellac.htm

[Michelle Rich]

heck if I know :-) Yes finishes can get "gluey" . Did the oil completely dry? How humid is it where you are? So many variables

[Roger Chandler]

Some finishes can go bad, but most of them just get thicker, and set up quicker if they have the chemical accelerators in them. You might be mixing too many different finishes, or possibly wax in the shellac. Not sure, as I don't use those finishes.

robo hippy

Thanks for the reply Reed......the Zinzser seal coat is 100% wax free shellac........that was not the issue, but perhaps the WTF did set up quicker than I realized......it was only about 65 degrees in my shop when I did this bowl....not too hot? :confused:

Michelle........I do believe the oil was completely dry......antique oil dries fast anyway, and that "gluey thing"....you might be on to something there........reason for my post........the humidity was not too bad......sort of a sunny warm October day here yesterday.......high of about 78 degrees.

[Prashun Patel]

I'm thinking one of 2 scenarios:

1) Contamination on the steel wool? Did you use anything to lube with? If there was some residual solvent on the surface, it could affect adhesion of the wtf.

2) Finishes can definitely go bad. This usually results in a coating that won't set or cure properly or at all. It could be the case that you applied the 4 coats of wtf too quickly. Applying subsequent coats to a not-quite-dry coat could lead to problems as the residual solvent escapes and the under coats settle underneath hardened skins of top layers. You can get dimples, ripples, or just gumminess.

[Peter Elliott]

Tell us about the shellac? If you sprayed it via rattle can, that's a 1/2lb cut, if you used it out of a paint can, that's a 2lb cut... If you are applying via brush/rag, you need to be in the 1lb cut range or even less, doing a few coats at a time. 2lb cut CAN be applied but depending on how the can was, you might be putting on too much product. And contrary to some, you need to sand down the first coat of shellac a little more than just de-nibs. Get the 1st coat super smooth, don't be afraid of removing that 1st coat to the eye. Then lay down 2-4 more light coats. Remember, shellac coats will burns into each layer, so 3-4 coats makes for a nice "sealer" or first step into the finish process. All this goes fairly fast too. Depending on weather/shop temps, you can have this done in 1-4hrs.

Same goes with the WTF. It shouldn't be laid on thick at all. Very light coats. The hardest part about WTF is the lap lines because it dries fairly quick. So working one side of the bowl/work at a time is best. You should really do light coats, let it CURE for a few days and then buff. WTF can be dry to the touch but it needs to be fully cured before buffing.

[Peter Elliott]

whoaaaaa... hold the phones.....

I just re-read your post Roger. (sorry 2hrs of sleep last night from the job).

You put on "Antique Oil" first?

OK, that's the problem. The 3 products you used don't jive too well.. Sure, you can throw anything onto a piece of wood... but the finish schedule is kinda out of whack (to me).

Antique Oil - is a oil/resin finish.. Mostly BLO and Poly with some accelerators. The BLO part is good, the POLY part is what hurt your finish.

I can almost bet the Antique Oil never cured.

I would not use Antique Oil with these other products. Oil/Resin finishes are best on it's own with maybe a wax top coat.

WTF alone gives a warm tone to it.. especially after a 4 coats and I would have just used WTF.

But if you really wanted to oil or give it a rich tone.

1. oil - either BLO or Walnut
2. shellac -dewaxed 1/2lb cut to 1lb mix
3. WTF

and not Antique oil as a top coat here (3).

Best part is you can remount it.. sand and start with shellac and WTF. That's what I would do here.

[Prashun Patel]

In general, I agree it's not good to put hard finishes like shellac over soft oil/varnish finishes, but it sounds like he just used a modest amount as a color enhancer. I don't think the AO is the problem. He also used Sealcoat as a barrier between that and the wtf, so any incompatibility of the poly with any top coat would be solved.

[Peter Elliott]

It's not a good idea to put shellac over poly resin, the shellac isn't much of a "barrier" here because it not going to seal off that Antique Oil well.

[Bernie Weishapl]

Roger I agree with Peter. I made the same mistake you did and found out the hard way don't put a hard finish under WTF. If I want a amber color I put a coat of dewaxed shellac. I use both the super blonde and I can't remember for sure but a blonde that puts a amber hue to the wood if I want it. I have also found that another problem is Jeff Weiss told me that the Zinnser sealcoat doesn't play well with Target WB poly and he said he that was one of the problems I was having with their poly and bets it is the same for WTF. He recommends mixing your own shellac. So that being said I only mix with DNA and shellac from shellac.net.

[Richard Jones]

I didn't see the part about the AO either, sorry.

Note to self: read carefully before responding......................

Regardless, shellac can go bad.............

[Roger Chandler]

Thanks guys.........I learned a lot from your responses........although I am puzzled a bit that AO should not be used as a color enhancer...........I have done this same proceedure before and had good success. I coated 2 coats of AO on the piece about 5 minutes apart.........then waited for a few minutes........perhaps the AO finish was not dry enough ......."cured" for sake of application of the WTF............

Thank you for your responses.......if you have any additional comments on my latest statement, the I welcome your input.....this finishing thing has so many variables, that it is hard to get something nailed down.........I really do appreciate all your insights and helpfulness!!!

[Peter Elliott]

Roger, AO is "brew" of components. 1st being BLO, 2nd Poly, 3rd Carriers like Mineral Spirits etc. As you know, BLO needs to dry and dry more than the touch of the finger. The oil needs to polymerize or we say "cure". It's doubtful that could be done in 1hr. Poly on the other hand can dry to the touch in 1hr but needs to cure for a lot more than that. The carriers are used to help "spread" the two and help level the combine ingredients, those evaporate fairly quick. The BLO is what is "enhancing" in the AO.

All dry times depend on weather outside, shop temp, how much you put on, how old the product is and the wood type. So no one can say exactly how long the dry time is but generally over night is a good estimate for a Oil/Varnish brew. For just BLO, you can do a super light coat, I mean just a little rubbed in and get away coated it in a hour or two. Anything more than that, the oil doesn't cure and putting something over it risks the chance of being cloudy, not curing, orange peel, dimples, etc..

I like AO but I make my own. It's part of the old oil/varnish family from many moons ago.. 1/3 oil, 1/3 varnish 1/3 mineral spirits. AO is a bit more refined in the carriers. But again, AO is great on it's own. I like to add Ren Wax as the final top coat, lightly buffed.

On the other hand. I've use a touch of Walnut oil, let it dry for a day or 2 and apply WTF. To me there is no need to use shellac here.

[Roger Chandler]

Roger, AO is "brew" of components. 1st being BLO, 2nd Poly, 3rd Carriers like Mineral Spirits etc. As you know, BLO needs to dry and dry more than the touch of the finger. The oil needs to polymerize or we say "cure". It's doubtful that could be done in 1hr. Poly on the other hand can dry to the touch in 1hr but needs to cure for a lot more than that. The carriers are used to help "spread" the two and help level the combine ingredients, those evaporate fairly quick. The BLO is what is "enhancing" in the AO.

All dry times depend on weather outside, shop temp, how much you put on, how old the product is and the wood type. So no one can say exactly how long the dry time is but generally over night is a good estimate for a Oil/Varnish brew. For just BLO, you can do a super light coat, I mean just a little rubbed in and get away coated it in a hour or two. Anything more than that, the oil doesn't cure and putting something over it risks the chance of being cloudy, not curing, orange peel, dimples, etc..

I like AO but I make my own. It's part of the old oil/varnish family from many moons ago.. 1/3 oil, 1/3 varnish 1/3 mineral spirits. AO is a bit more refined in the carriers. But again, AO is great on it's own. I like to add Ren Wax as the final top coat, lightly buffed.

On the other hand. I've use a touch of Walnut oil, let it dry for a day or 2 and apply WTF. To me there is no need to use shellac here.

Thanks for that info Peter......it is very helpful.........gracious!!! :)

[Fred Belknap]

Roger thanks for the thread. I have used quite a bit of AO an found that it can feel dry and still be wet inside the wood. I put some bowls that I use AO on and let set overnight then used the vacuum chuck, it sucked wet finish out of the wood.

[Roger Chandler]

Roger thanks for the thread. I have used quite a bit of AO an found that it can feel dry and still be wet inside the wood. I put some bowls that I use AO on and let set overnight then used the vacuum chuck, it sucked wet finish out of the wood.

Yep........I think that is what happened.....it felt dry to the touch and well........you know! Thanks Fred!

[Ryan Baker]

Looks like elm to me.

I agree with Peter on the finish.

[Roger Chandler]

Looks like elm to me.

That was my second/third guess, Ryan.......the box had some elm in it and this looked a bit more like cherry in the log form, but once I saw the end grain features when turning the bowl, I thought it might possibly be elm...........I am still leaning just a bit towards cherry because of the grain it showed in the log piece I had.......I might be wrong however, and gladly acknowledge that! ;):confused:

[Bill Boehme]

Roger, I agree completely with Peter Elliot. If you wanted to add a bit of amber color to the wood, shellac is perfectly capable of doing that without anything beneath it, but shellac should not be used over oil. It can sometimes even be problematic on especially oily woods, especially if a varnish like polyurethane is used over the shellac. Dewaxed shellac can be used on bare wood before some other types of finishes, but be careful about what other finishes you use. Zinsser seal coat is too thick in my opinion and it also has wax in it despite what the can says. You can pour it through a coffee filter and see that there is wax in it. Even the supposed dewaxed super blonde shellac flakes that I buy has plenty of wax in it. I always filter it after mixing up a batch. Pick one finish and go with it. Applying layers of different types of finish seems to always create problems. If I am not mistaken, Woodturners Finish is solvent based which means that it will dissolve the shellac. Since the two different types of finish are not really compatible when dissolved together, a mess is one possible outcome.

[Roger Chandler]

Roger, I agree completely with Peter Elliot. If you wanted to add a bit of amber color to the wood, shellac is perfectly capable of doing that without anything beneath it, but shellac should not be used over oil. It can sometimes even be problematic on especially oily woods, especially if a varnish like polyurethane is used over the shellac. Dewaxed shellac can be used on bare wood before some other types of finishes, but be careful about what other finishes you use. Zinsser seal coat is too thick in my opinion and it also has wax in it despite what the can says. You can pour it through a coffee filter and see that there is wax in it. Even the supposed dewaxed super blonde shellac flakes that I buy has plenty of wax in it. I always filter it after mixing up a batch. Pick one finish and go with it. Applying layers of different types of finish seems to always create problems. If I am not mistaken, Woodturners Finish is solvent based which means that it will dissolve the shellac. Since the two different types of finish are not really compatible when dissolved together, a mess is one possible outcome.

Thank you Bill!!! Finishing is an area I have some work to do to get really good at.....there are times I get good results, then every once in a while I get the "mess" you referred to........inconsistent! Information like what I have received on this thread is a truly valuable resource.......thanks to all!