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Forum topic by Croikee posted 09-26-2020 03:33 PM 303 views 1 time favorited 14 replies Add to Favorites Watch
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Croikee

31 posts in 45 days


09-26-2020 03:33 PM

Buying wood today for a project I got suggestions for, here, a few weeks ago. I’m going with plywood and edgebanding as recommended. I know I am going to stain it with General Finishes wb dye, then a clear coat of either their poly or lacquer.

I do have two questions though:

1) Should I use a sanding sealer first?

2) I’m attaching a picture of a project similar to mine. It will have a long narrow-ish tube portion for a yoga mat to sit in. I’m planning on using a sanding sealer BEFORE assembly, but was planning on staining once assembled for uniformity. That would of course leave the inside of the “tube” portion unstained & un lacquered.

First, is that the right process? If so, will the sanding sealer be a sufficient sealer for the wood? Or should I seal, stain and lacquer each piece prior to assembly, then do one final coat of lacquer once assembled? Thank you all!

John


14 replies so far

View Fred Hargis's profile

Fred Hargis

6502 posts in 3376 days


#1 posted 09-26-2020 04:09 PM

Well, in general sanding sealers aren’t more than a very thin coat of finish (of some type), that’s what seals the wood. If you seal the wood before you apply the dye…it isn’t going to penetrate the wood and provide color. I guess I wonder why you think you need the sanding sealer. My approach would be a little different. I would skip the sanding sealer, and dye what ever parts you want. Now, with a WB dye you can apply the de to the unassembled pieces and still glue them together…the dye doesn’t have any “binders” to interfere with the glue. The problem may be when you top coat. A top coat of GF “poly or lacquer” isn’t very descriptive. If you top coat water based dye with a water based finish, you pretty much have to spray it. Brushing it on will almost certainly redissolve the dye and cause streaking. That doesn’t happen, however, if you use a solvent based top coat. One other thing: the dye will cause grain raising…the wood will feel like sandpaper after the dye dries. If you apply a top coat (brushed/sprayed solvent, or sprayed waterbone) t will seal the raised fibers; all you have to do is smooth it out after the top coat dries and you’re done with the grain raising. So, I would apply the dye, then top coat, smooth it, then apply as many more top coats as I though it needed. There’s a couple of hundred other ways to do this, and that’s only mine.

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

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LesB

2622 posts in 4326 days


#2 posted 09-26-2020 04:23 PM

The use of a “sanding sealer” depends on the type of wood your are staining. For example, pine or fir do not accept stain uniformly so a sealer such as dilute shellac helps control the penetration of the stain to even it out. Other hard woods like maple, birch, beech, etc do not need a sealer before staining. Shellac can be applied with a lint free cloth and wiped on. It dries quickly. Sand lightly and apply a second coat if it appears needed.
As is commonly stated here about finishes…test first on a scrap piece before you start….

I personally would not use any coating of the wood before assembly…I’m assuming you will glue it. If you are using screws or nails it makes no difference.

Leaving the inside of the tube unfinished could potentially create a problem of expansion and contraction of the wood in an environment where the ambient humidity varies significantly so I would finish all surfaces. A wipe on poly is easy to apply in cases like this. It would require 3 or 4 coats with a light sanding between coats.

Good luck

-- Les B, Oregon

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Aj2

3414 posts in 2680 days


#3 posted 09-26-2020 04:33 PM

I think if you understand the purpose of the sanding sealer you’ll know what to do.
We use sanding sealer to build a base for the top clear coat. Sanding sealer is very easy to powder out. You can use the top coat as a base coat but it’s not that easy to sand it might take days to dry enough to sand with Corning up your paper.
But sanding sealer drys so fast you get a base coat done quickly.
Like Fred mentions if you want to color the wood do it first before the sealer. The sealer will close out the wood cells so they won’t take color very well at all.
That’s a neat looking simple project
One more suggestion protect your lungs from breathing finish it’s very bad even water based stuff. Might even be worse.
Good Luck

-- Aj

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Croikee

31 posts in 45 days


#4 posted 09-26-2020 04:37 PM



Well, in general sanding sealers aren t more than a very thin coat of finish (of some type), that s what seals the wood. If you seal the wood before you apply the dye…it isn t going to penetrate the wood and provide color. I guess I wonder why you think you need the sanding sealer. My approach would be a little different. I would skip the sanding sealer, and dye what ever parts you want. Now, with a WB dye you can apply the de to the unassembled pieces and still glue them together…the dye doesn t have any “binders” to interfere with the glue. The problem may be when you top coat. A top coat of GF “poly or lacquer” isn t very descriptive. If you top coat water based dye with a water based finish, you pretty much have to spray it. Brushing it on will almost certainly redissolve the dye and cause streaking. That doesn t happen, however, if you use a solvent based top coat. One other thing: the dye will cause grain raising…the wood will feel like sandpaper after the dye dries. If you apply a top coat (brushed/sprayed solvent, or sprayed waterbone) t will seal the raised fibers; all you have to do is smooth it out after the top coat dries and you re done with the grain raising. So, I would apply the dye, then top coat, smooth it, then apply as many more top coats as I though it needed. There s a couple of hundred other ways to do this, and that s only mine.

- Fred Hargis

Fred, I needed to be more clear for sure. The General Finishes I want to use are both water based, their dye and their lacquer. I have a nice 4 stage turbine hvlp system I just got that will spray it just fine. SO, spraying is my planned method of delivery. So, if I am hearing you right, you would dye all pieces unassembled, then assemble, then final coat(s) of lacquer?

I am assembling with dowels and glue.

View Croikee's profile

Croikee

31 posts in 45 days


#5 posted 09-26-2020 04:38 PM



The use of a “sanding sealer” depends on the type of wood your are staining. For example, pine or fir do not accept stain uniformly so a sealer such as dilute shellac helps control the penetration of the stain to even it out. Other hard woods like maple, birch, beech, etc do not need a sealer before staining. Shellac can be applied with a lint free cloth and wiped on. It dries quickly. Sand lightly and apply a second coat if it appears needed.
As is commonly stated here about finishes…test first on a scrap piece before you start….

I personally would not use any coating of the wood before assembly…I m assuming you will glue it. If you are using screws or nails it makes no difference.

Leaving the inside of the tube unfinished could potentially create a problem of expansion and contraction of the wood in an environment where the ambient humidity varies significantly so I would finish all surfaces. A wipe on poly is easy to apply in cases like this. It would require 3 or 4 coats with a light sanding between coats.

Good luck

- LesB

If I am reading right, you are saying do not stain/dye before assembly, but then you are saying you would not leave the inside of the tube unfinished. So if I assemble first, how would you go about getting the inside of the tube to prevent that possible expansion? Again, all water based, using a sprayer.

Thank you for your input!

View Croikee's profile

Croikee

31 posts in 45 days


#6 posted 09-26-2020 04:39 PM



I think if you understand the purpose of the sanding sealer you’ll know what to do.
We use sanding sealer to build a base for the top clear coat. Sanding sealer is very easy to powder out. You can use the top coat as a base coat but it’s not that easy to sand it might take days to dry enough to sand with Corning up your paper.
But sanding sealer drys so fast you get a base coat done quickly.
Like Fred mentions if you want to color the wood do it first before the sealer. The sealer will close out the wood cells so they won’t take color very well at all.
That’s a neat looking simple project
One more suggestion protect your lungs from breathing finish it’s very bad even water based stuff. Might even be worse.
Good Luck

- Aj2

Thank you! So I hear you saying stain/dye, then use a sanding sealer to seal/smooth everything out, then assemble and lacquer? That sanding sealer would be sufficient for the inside of the tube that the spray top coat can’t reach?

I have a respirator for paint, good to go on that front :)

View MPython's profile

MPython

308 posts in 695 days


#7 posted 09-26-2020 04:42 PM

You can tint shellac and water born finishing products by simply adding Trans Tint dye to the finish before it’s applied (see link below).That may be a helpful in this case. If you use water borne finishing products like water born polyurethane, you still have to deal with the grain raising issue.
Just a thought.

https://homesteadfinishingproducts.com/transtint-liquid-dyes/

View Fred Hargis's profile

Fred Hargis

6502 posts in 3376 days


#8 posted 09-26-2020 04:47 PM



Fred, I needed to be more clear for sure. The General Finishes I want to use are both water based, their dye and their lacquer. I have a nice 4 stage turbine hvlp system I just got that will spray it just fine. SO, spraying is my planned method of delivery. So, if I am hearing you right, you would dye all pieces unassembled, then assemble, then final coat(s) of lacquer?

I am assembling with dowels and glue.
- Croikee

I don’t know if i would dye first, I normally do not. But if the color has to be applied to a hard to reach area, there is no reason not to dye it first and save your self some grief. So my point was that you can dye first, if you want. Knowing that you will be spraying I would assemble it, then dye it, then use the top coat. Sand the first top coat back slightly to smooth it out, then apply however many coats you want.

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

View Croikee's profile

Croikee

31 posts in 45 days


#9 posted 09-26-2020 04:49 PM


Fred, I needed to be more clear for sure. The General Finishes I want to use are both water based, their dye and their lacquer. I have a nice 4 stage turbine hvlp system I just got that will spray it just fine. SO, spraying is my planned method of delivery. So, if I am hearing you right, you would dye all pieces unassembled, then assemble, then final coat(s) of lacquer?

I am assembling with dowels and glue.
- Croikee I don t know if i would dye first, I normally do not. But if the color has to be applied to a hard to reach area, there is no reason not to dye it first and save your self some grief. So my point was that you can dye first, if you want. Knowing that you will be spraying I would assemble it, then dye it, then use the top coat. Sand the first top coat back slightly to smooth it out, then apply however many coats you want.

- Fred Hargis

I appreciate your quick replies. What would you do about the center of the tube portion? Maybe just wipe that down with a wipe type sealer? I imagine sealing is more improtant than matching the sealers perfectly, it won’t be visible.

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Fred Hargis

6502 posts in 3376 days


#10 posted 09-26-2020 05:15 PM

I would want that part finished, in the pic it looks to open from the wall side, is that not the case? If it isn’t open, then that part may have to be finished prior to assembly. If you do so, mask the areas to be glued. Or consider putting the back on last (after finishing), if it has one.

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

View Croikee's profile

Croikee

31 posts in 45 days


#11 posted 09-26-2020 05:22 PM



I would want that part finished, in the pic it looks to open from the wall side, is that not the case? If it isn t open, then that part may have to be finished prior to assembly. If you do so, mask the areas to be glued. Or consider putting the back on last (after finishing), if it has one.

- Fred Hargis

SUCH AN OBVIOUS FIX! The tub portion will be attached to a back portion of plywood, but I can drill the holes for the dowels, tape them, then assemble the tube portion and finish it BEFORE attaching it to the back. THANK YOU! Such a obvious solution I would have never thought of.

John

View Fred Hargis's profile

Fred Hargis

6502 posts in 3376 days


#12 posted 09-26-2020 05:23 PM

Be sure to try your finish plan on a piece of scrap before committing to your project….sometimes things don’t look the way we envision them in the beginning.

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

View MPython's profile

MPython

308 posts in 695 days


#13 posted 09-26-2020 05:35 PM

Aj2 said, “The sealer will close out the wood cells so they won’t take color very well at all.” That’s true if you use the sealer full strength. If you dilute it, it is a pre-stain conditioner called a “wash coat” that helps even out the penetration of stain on woods that are prone to blotching. Shellac is probably the most universal sealer. It adheres to and seals everything and almost all common finishes adhere to it very well. Shellac has also traditionally been used as a finish. The concentration of shellac is expressed as the “pound cut,” I.E., a 1 pound cut (1#) is one pound of shellac flakes to a gallon of solvent (alcohol). Shellac sealer is usually a 2# cut, and shellac used for the final finish is more concentrated, like a 3# or 4# cut.

Wood is a collection of hollow fibers, like a bundle of straws. Stain applied to wood’s long grain soaks down between the fibers and usually gives you a fairly even color. But if stain is applied to end grain, the hollow fibers suck it up (capillary action) and absorb much more of it, resulting in a deeper or darker coloration. When the fibers on a board undulate along its length, the rising fibers are cut off when the face of the board is planed or sanded, leaving the hollow ends exposed on the surface. When stain is applied to the long grain of a board that has some of these truncated fibers on the surface, the result is uneven absorption of the the color known commonly as “blotching,” because the the little fiber tubes that have been cut off suck up more of the stain than the long fibers that have not been cut.

A thin coat of shellac, like a 1# cut, usually solves this problem. It is applied first, before the stain. It acts like any other liquid; it soaks down between the wood fibers and is sucked up by any of the hollow fibers that have been cut and present an open capillary tube on the surface. When it dries (it dries very quickly), it solidifies and seals the ends of the open tubes, preventing them from sucking up the stain when it is applied later. A light sanding with 220 or 320 grit paper after the sealer has dried removes almost all of it from the long grain fibers, making them receptive to the stain, but it remains in the hollow tubes because it has soaked deeply into them and is not all sanded away. When the stain is applied after a wash coat of sealer, it goes on much more evenly and the coloration is much more consistent than it would have been without the sealer. At this point you can apply just about any finish you want.

If you want to try this process, you don’t need to worry about how to measure and mix a 1# cut of shellac. Buy a can of Zinsser Seal Coat. It is a commercially available pre-mixed 2# cut of shellac sealer. Dilute it 50-50 with denatured alcohol and you’ve got a 1# cut for your wash coat. It can be wiped or brushed on, but move fast because it dries very quickly.

Sorry for the long dissertation, but it’s an interesting process, and the way it works is not immediately evident.

View CWWoodworking's profile

CWWoodworking

1092 posts in 1061 days


#14 posted 09-27-2020 02:32 AM

Assemble, stain, 2 coats of precat lacquer. No sanding sealer. No shellac/sealcoat.

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