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Failing finish and not sure why

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Forum topic by sansoo22 posted 12-17-2019 06:05 PM 640 views 0 times favorited 16 replies Add to Favorites Watch
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sansoo22

1905 posts in 944 days


12-17-2019 06:05 PM

As some of you are aware I like restoring old hand planes. My typical finish process for totes and knobs is to apply a flood coat of danish oil to pop the grain, wipe the excess off after about 15 min or just before it gets tacky, let that sit and cure for 3 days, spray a coat of clear shellac as a sealer, and top coat with semi gloss lacquer. The final step is a very light wax with Renaissance wax just because i like how it feels.

I have done over a dozen planes this way without issue so far. Since moving to my new shop I have had 3 finishes fail on me and I’m not sure why. And by fail I mean the top coat flashes off or I had one that looks like the top coat oxidized. I don’t know if its a different moisture content in the air or the fact the bigger space is effecting drying times. If im finishing in the winter months I leave all my handles in a make shift drying cabinet over by the space heater. I will say the shop heater is probably not up to task for the bigger space so maybe that’s it.

The ones that failed have been sanded back to bare and I have moved my finishing work inside to the kitchen counter much to the chagrin of my girlfriend who thinks kitchens are for cooking only. I plan to let those cure for up to 5 days this time to see if it makes a difference. In the meantime I thought I’d reach out to see if I can get any pointers.

Thanks


16 replies so far

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HokieKen

19945 posts in 2428 days


#1 posted 12-17-2019 06:25 PM

Wow. You go to more effort for finishing tool handles than I do for furniture!

I’ve never had much luck with lacquer personally. I’d advise trying a poly coat for the top using wipe on poly. For me, totes and knobs get a mix of poly/blo/ms for a couple coats then a coat of paste wax.

-- I collect hobbies. There is no sense in limiting yourself (Don W) - - - - - - - - Kenny in SW VA

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sansoo22

1905 posts in 944 days


#2 posted 12-17-2019 06:39 PM

Thanks Kenny I will give that a try. I’ve used spray on poly before and just wasnt pleased with the result. It has a wonderful satin sheen but looks to “plasticy” for my taste. Maybe the wipe on wont build up so thick.

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HokieKen

19945 posts in 2428 days


#3 posted 12-17-2019 06:43 PM

That’s exactly why I like wipe-on, it doesn’t look plasticky and doesn’t feel it either. I usually use a single coat if I’m using it as a topcoat on tool handles. A little protection without looking like it :-) I prefer to just mix everything up in a wiping varnish though. It’s super easy and effective in my experience.

-- I collect hobbies. There is no sense in limiting yourself (Don W) - - - - - - - - Kenny in SW VA

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OhioMike

89 posts in 3452 days


#4 posted 12-17-2019 06:44 PM

Is the shellac you are using the DEWAXED variety?

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sansoo22

1905 posts in 944 days


#5 posted 12-17-2019 06:49 PM


Is the shellac you are using the DEWAXED variety?

- OhioMike

I’m not entirely sure. I use the Zinser Bulls Eye rattle can. Im assuming since it doesnt say dewaxed that it probably isnt. I only use it to prevent anything from the lacquer reacting with the danish oil.

Edit: After a quick trip to Google it appears the shellac im using is not dewaxed and i should be using a seal coat instead

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Fred Hargis

7302 posts in 3783 days


#6 posted 12-17-2019 07:51 PM

I doubt the shellac is causing the problem. The adhering becomes a problem when you combine it with either a urethane oil finish (the urethanes are the problem) or some of the water borne finishes. The shellac you use will stick to the BLO just fine, and the lacquer actually burns itself into the shellac coat.

-- Our village hasn't lost it's idiot, he was elected to congress.

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Rich

7578 posts in 1879 days


#7 posted 12-17-2019 08:05 PM

Photos would help. I’m not sure what you mean by flashes off and oxidizes. Flash time refers to the evaporation of solvents in an evaporative finish like lacquer, and flashing off is the term for that process. It’s not a term for a flaw in the finish. By oxidizing, do you mean the finish gets cloudy?

Lacquer can trap moisture in a humid environment, causing blush, or a whitish haze in the finish. Is that what you’re seeing? If so, there are measures to take to prevent or remove it. To prevent it, use a retarder thinner. Sherwin Williams makes one called K27. It’s a blend of very slow evaporating solvents that allow the moisture to evaporate before being trapped in the finish. To repair a finish with blush in it, the retarder thinner can be sprayed directly on the finish. It will dissolve it and allow the moisture to evaporate.

If you are working with aerosols, there’s nothing you can do to add a retarder to the spray, however Mohawk makes a product called No Blush which is the same retarder thinner in an aerosol. You can spray that on a finish that has blushed to dissolve it and let the moisture evaporate. It can take multiple applications to completely remove the blush.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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Woodknack

13585 posts in 3670 days


#8 posted 12-17-2019 08:16 PM

I’m with Kenny, simplify. But my guess is humidity. If nothing else changed and it was working before but not working now, then it almost has to be environmental unless you’ve overlooked something basic.

-- Rick M, http://thewoodknack.blogspot.com/

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sansoo22

1905 posts in 944 days


#9 posted 12-17-2019 08:26 PM

Rich – I wasn’t sure what terms to use and i already sanded back down so no photos unfortunately. The white haze you are talking about it what I’m mostly seeing. At first i assumed it was just some spots i hadnt buffed correctly after waxing. So got out a buffing clothe and after it looked as tho my top coat simply came off. Like the adhesion completely failed.

The one that I said oxidized had bright white flaky spots similar to corrosion on battery terminals if that helps. That one had been introduced to some sort of chemical before refinishing. You could see a thumb and 3 fingerprints of something that ate into the original finish. Might be safer to call that one a fluke for now.

I have been using aerosols because its quicker but I can switch to brush on and pick up some K27. There is a Sherwin Williams very close by. It has been snowing and higher humidity here lately. We got 8” of a heavy wet snow recently.

Fred – The danish oil i was using is a urethane type so wont use that anymore. That could explain the adhesion issue i mentioned. I’ve got plenty of handles i can try different things on. Will give BLO a shot next and see what happens.

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Rich

7578 posts in 1879 days


#10 posted 12-17-2019 10:27 PM


Rich – I wasn t sure what terms to use and i already sanded back down so no photos unfortunately. The white haze you are talking about it what I m mostly seeing. At first i assumed it was just some spots i hadnt buffed correctly after waxing. So got out a buffing clothe and after it looked as tho my top coat simply came off. Like the adhesion completely failed.

The one that I said oxidized had bright white flaky spots similar to corrosion on battery terminals if that helps. That one had been introduced to some sort of chemical before refinishing. You could see a thumb and 3 fingerprints of something that ate into the original finish. Might be safer to call that one a fluke for now.

I have been using aerosols because its quicker but I can switch to brush on and pick up some K27. There is a Sherwin Williams very close by. It has been snowing and higher humidity here lately. We got 8” of a heavy wet snow recently.

- sansoo22

I led you down the wrong path. Lacking information and photos, I made an assumption about the blushing that clearly is not the case. You’re better off sticking with your spray lacquer versus brushing it. Just pay attention to the conditions you spray it in. A good rule of thumb is not to spray lacquer below 60ºF or above 60% humidity. As with all generalizations, there is leeway with those numbers, but low temps and high humidity are issues with lacquer.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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sansoo22

1905 posts in 944 days


#11 posted 12-17-2019 10:57 PM

^^^ I think we have a winner. I don’t recall humidity the last day a i sprayed a batch but i know it was in range. I do know for a fact temp in the shop was 55 because i remember thinking to myself…”sure doesnt feel 55 in here…meh close enough” and sprayed away. Next time i think that I will remember that Rich is smarter than me and turn up the heater for a little while.

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sansoo22

1905 posts in 944 days


#12 posted 12-23-2019 03:54 AM

Thanks again for the pointer Rich. Temperature seemed to be the culprit. Spent the last few evenings insulating my old wooden garage door. Got out the 80,000 BTU propane heater today and ran it on low for about 20 min and brought the temp up to 68 deg in the shop with humidity around 45%.

Sprayed 2 sets of handles and both sets turned out great!

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Rich

7578 posts in 1879 days


#13 posted 12-23-2019 04:04 AM


Thanks again for the pointer Rich. Temperature seemed to be the culprit. Spent the last few evenings insulating my old wooden garage door. Got out the 80,000 BTU propane heater today and ran it on low for about 20 min and brought the temp up to 68 deg in the shop with humidity around 45%.

Sprayed 2 sets of handles and both sets turned out great!

- sansoo22

That’s awesome. Thank you so much for letting me know.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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tomsteve

1182 posts in 2509 days


#14 posted 12-25-2019 09:09 AM

that oxidizing or whitening is called blushing caused by moisture..evaporating solvents can lower surface temp below dew point. lacquers are notorious for it.

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bondogaposis

6069 posts in 3641 days


#15 posted 12-25-2019 01:52 PM

For my tool handles and totes I stop at the danish oil step. You are way over complicating. Keep it simple.

-- Bondo Gaposis

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