How to Prevent Corning When Sanding Shellac
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- Опубліковано 19 жов 2015
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Shellac is a great finish, and can be used for many different aspects of finishing. However, some woodworkers run into problems when sanding shellac, such as corning.
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I refinish cabinets and furniture for my business. I never use shellac only pre catalyzed lacquer or conversion varnish. I came up with a trick to sand off shellac. Spread regular white flour on the surface it prevents the sandpaper from clogging
These are great tips. People often think shellac will dry so fast only because it's dry to the touch in no time. But in reality it can take weeks to dry completely.
First time I used shellac I had put it on thick. However I didn’t do my last coat sanding for months. It sanded perfectly. Second time was Exact same type of project. I put shellac on thick but tried to sand 48 hrs later. Sanded good at first but then I hit gummy areas. Lesson learned. You can apply in thick coats and it will dry. It just takes months.
Power sanding at low rpm with vacuum assisted dust extraction helps reduce corning. I just have a Shop-vac hooked directly to my sander via an adapter. At low rpm, a sanders vane based air flow is to low to be effective, hence the vacuum assist. Corns can be removed with a stiff brush and ammonia solution on sandpaper that is water resistant. Also shellac is made from the casing the laq bug secrets for protection, no poop involved
Perfect. Best video out fo the five I just watched about shellac. Thank You
Glad you liked it!
Great information I never knew. thank you
As always... Patience padawans. Let it dry! LOL. Informative as always.
Great tip, thank you.
Excellent, thanks
In restoring old furniture, I've found this to be a problem as well. I only use hand-sanding, and I think what happens is that if the sandpaper is worn down (or even if it's not, sometimes), the heat generated from sanding causes the shellac to get sticky and ball up like this. The solution seems to be to slow down, or get fresh paper.
Thank you
I have found that I get these when I put to much pressure on my sandpaper, let the sandpaper do its job with a light touch.
Hi GeorgeGood information, I like that sanding block where can I get one?Regards Murray
You can scrape it, too.
Thanks, now I know!
George, do you need to sand shellac between coats? Doesn't each coat melt into the previous coat and they all become one coat? I just sand before the first coat and before the last coat. And yes, if you aren't getting white powder you're probably sanding too soon. Shellac tempts you to do that :)
at 1:42, the video says the shellac could still be wet underneath a top layer when applied too thickly. However, I was just reading the chapter on shellac in “Understanding Wood Finishing” (1994 edition), which describes shellac as an evaporative finish that dries from the bottom to the top, and seems to contradict this specific explanation for why thicker layers are more likely to corn. Maybe there’s a subtlety that I’m missing, or I misunderstood what I read.
I'd love to understand this, too. Did you get any more info?
@@cmpetersonstudio unfortunately, I did not, and I personally have not used shellac very much
well it's still the same basic idea, that the thicker areas are just not going to be as dry as the thinner ones unless you wait longer
Is this an acceptable way to sand shellac when it is the final coat? What about wet sanding prior to buffing/polishing? What lubricant?
Hi Rick,
You can use this approach, but you should be starting the process with a much finer grit. You can wet sand with distilled water, and a couple drops of liquid detergent. Start with 1000 grit and a rubber sanding block, and progress through 2000 grit paper.
Paul
Woodworkers Guild of America
No don't wet sand shellac
Thanks George, this is something that we may discover by experience, but you explained quite technical!!!!
Just a word. Do you have any reference on this sanding block?? I guess this block use the regular sanding pads for the electric sanders, isn´t it?
+Mario Lagarde The sanding block I use in this video is from Festool. It’s set up for hook and loop and accepts 6” (150 mm) sanding discs. They make a variety of these. One part number is Festool 495966 HSK-D-150 Round Sanding Block
+WoodWorkers Guild Of America Thanks!!! After watching the video I found some of them in UK, but let´s check on the Festool page instead.
Good tips....I never knew that shellac 'went off' as in...became rubbery. ..assumethis is for ready mixed stuff as opposed to the actual shellac flakes?
Oakleaf700 No, I’m told by those with far more experience than myself that All shellac has a shelf life, pre made or self made from flakes or buttons. Maximum about 18mths if I remember rightly
Thanks for video. What grit sand paper are you using?
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Good explanation! Question: Can one expect to get better results with Shellac by mixing Flakes & Denatured Alcohol rather than using canned Shellac? Just curious................Thanks
Yes, from my research shellac has a shelf life and it’s best to buy fresh flakes and mix
Hi George,
I’m making big bass marimba bars (percussion instrument that will be struck thousands of times with a medium hard mallet and will vibrate like crazy over and over and over). Traditionally they finished with oils and waxs, though I want to experiment with other stuff. For my experiment phase-in order of best to worst-can you please suggest/brainstorm what you think might work out for coating/sealing wooden bars that will be taking a lot of inherent abuse? With all the beating and vibrating, for instance, might shellac or lacquer or polyurethane or wood hardener or an acrylic poor be too brittle, resulting in getting rattled and crushed to death and breaking apart microscopically over time? Also consider which finish would be the most scratch resistant. (Bars will be stored in stacks and slid against each other with the potential of dirt and sand bits in between. Thanks for brainstorming with me 👍🏻
Sam
Great question! I have forwarded it to our experts and they will reply here within 1-2 business days. Thanks!
@@Wwgoa Cool! Thanks.
I don't think that any of the finishes would crack from this impact. My first choice would be walnut oil; It doesn't offer any scuff resistance but it's easy to refresh/repair and you could use it almost immediately after reapplication. My second choice would be poly urethane because it offers the most scuff resistance.
Paul
@@Wwgoa Cool. Thanks Paul.
I'm still a novice with finishing wood. How about combinations? How 'bout a coat of oil then a coat of poly? Aside from the use of stains, are combinations of finishing-types a thing? If so, what are the most common combos, and which combos might be good for these marimba bars I'll be crafting? Thanks!
The 1st coat of shellac should be a 50% solution of alcohol and shellac. Lightly sand and proceeded to your other coats of shellac.
You can put tint in that first coat, too - e.g. “Ruské Red” shellac that looks like an old time foundry pattern.
I use Transtint dyes.
So how long do you need to wait before sanding? Is it true that shellac should be mixed with denatured alcohol?
Great question! Wait at least an hour before you sand. The shellac product shown in this video does not need to be mixed with anything. It's ready to go, directly from the can.
Paul
Sincerely,
Woodworkers Guild of America
I have the same problem with sanding sealer, it ruins my paper no matter how long it's cured. Other people say they don't have the problem, so I don't know what to do.
+Josef Roesler It might be worth trying one of the following:- a new can of sealer as it is possible that the age of the sealer is causing a problem with cure time
- a different brand sealer
- run a dehumidifier in the room where you are applying the finish.
WoodWorkers Guild Of America I guess living in humid Louisiana ain't helping.
I always mix 1:1 sealcoat shellac to denatured alcohol and apply thin coats. Should not feel sticky when dry.
I like to use cheap cooking oil while sanding. Just be careful things start to happen really fast and you'll bust through real fast.
Can you wet sand after shellac is dry?
Hello William,
I wouldn't suggest wet sanding on shellac as it has low moisture resistance.
Thanks for watching!
A question I want to put Zinsser Sealcoat on my hardwood floor lightly sand it then apply two coats of Bona Traffic HD what would be the best way to apply the Zinsser sealer on my floor approximately 400 sq ft and should I thin it? Thank you
I don't have a lot of experience with floor finishing, so I'm probably not the best one to ask. For large furniture projects that required a Zinsser Sealcoat sealer, I would spray it on. I don't know how feasible that would be for flooring.
Finer paper.
I really like the Woodglut plans.
I thought the title said "How to Prevent Coming...."
Wrong video.
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@@thatguyjoel9885 far more eloquent than I would have put it Joel. My first reaction to the Jesus mumbo jumbo was a simple two-word riposte, the second word being "off". Saddens me how they are still allowed to recruit openly for their cult.
But the question is what cut of shellac does he use?
@@brefnejowers9747 Jesus WAS a carpenter, after all! 😂😂