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Sanding Before and After Zinsser Sealcoat Shellac ( topcoat is General Finishes H20 Poly)

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Forum topic by Lovegasoline posted 08-28-2020 05:50 PM 1660 views 0 times favorited 18 replies Add to Favorites Watch
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Lovegasoline

176 posts in 1004 days


08-28-2020 05:50 PM

I’m spraying some pieces (cabinet/drawers). Using an HVLP conversion gun/compressor (Iwata). No stain or dye. I’m using Sealcoat hoping it will pop the grain a little and also darken the ends of the dovetails for contrast.

My finishing schedule is
1) Zinsser Sealcoat
2) General Finishes High Performance Topcoat, Flat sheen (a waterbourne poly). I assume 2 coats should do it?

1) What’s the recommended sanding grit prior to shooting the Sealcoat?
2) how long need I wait after shooting the Sealcoat before shooting the topcoat. (Good weather today, 85 degrees and 50% humidity). Generally one coat of Sealcoat is good?
3) what grit to sand the Sealcoat prior to the topcoat?
4) any tips on shooting General Finishes High Performance Topcoat?

-- “It is the beginning of wisdom to recognize that most men are fools and knaves, but it is the end of wisdom to embrace that vision.” -Arthur Kleps


18 replies so far

View Fred Hargis's profile

Fred Hargis

6717 posts in 3459 days


#1 posted 08-28-2020 06:01 PM

Everyone will have a different take on this, here’s mine:
I would sand to 180 and apply the seal coat. One coat should do it, and though it dries fairly quicky I would give it at least a couple of hours before top coating. The only reason I wold sand the seal coat is to smooth out any nibs, so a very fine grit should do….220 or even 320. No tips on the HP, you can thin it as much as 20% but I find it to spray very easily. I would worry about it drying a little too fast in your conditions…not allowing it to flow out. There are some retarders available if that’s a problem.

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

View AlaskaGuy's profile

AlaskaGuy

6335 posts in 3275 days


#2 posted 08-28-2020 06:07 PM



Everyone will have a different take on this, here s mine:
I would sand to 180 and apply the seal coat. One coat should do it, and though it dries fairly quicky I would give it at least a couple of hours before top coating. The only reason I wold sand the seal coat is to smooth out any nibs, so a very fine grit should do….220 or even 320. No tips on the HP, you can thin it as much as 20% but I find it to spray very easily. I would worry about it drying a little too fast in your conditions…not allowing it to flow out. There are some retarders available if that s a problem.

- Fred Hargis

Same here but I only go to 150 grit for drawers boxes.

-- Alaskan's for Global warming!

View Lovegasoline's profile

Lovegasoline

176 posts in 1004 days


#3 posted 08-28-2020 06:13 PM

Thanks. (Some of these parts are sanded to 220, some 300+/-)/
I’ll hit it with a Norton 220 sanding sponge after the shellac and between top coat applications.

-- “It is the beginning of wisdom to recognize that most men are fools and knaves, but it is the end of wisdom to embrace that vision.” -Arthur Kleps

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RadRider

8 posts in 144 days


#4 posted 08-29-2020 02:20 AM

I would do 320 grit.

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RadRider

8 posts in 144 days


#5 posted 08-29-2020 02:22 AM

.

View angelosart's profile

angelosart

14 posts in 175 days


#6 posted 08-30-2020 03:32 PM

Just my opinion:

1) What’s the recommended sanding grit prior to shooting the Sealcoat? 220 sanding, 150 might give you more pop in the grain. Brushing sealcoat will give you more pop as well

2) how long need I wait after shooting the Sealcoat before shooting the topcoat. (Good weather today, 85 degrees and 50% humidity). Generally one coat of Sealcoat is good? An Hour, 2 coats.

3) what grit to sand the Sealcoat prior to the topcoat? 320

View Rich's profile

Rich

6385 posts in 1555 days


#7 posted 08-30-2020 03:42 PM


Just my opinion:

[...]

- angelosart

Based on what? Why would brushing “give you more pop?” Why would 150 give you more pop than 220?

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

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Lovegasoline

176 posts in 1004 days


#8 posted 08-30-2020 10:25 PM

Here’s the results.

The Zinsser Sealcoat has completely transformed a moderately handsome wooden object into a dull, washed-out, drab looking, piece of nothing. It has obscured and reversed all of my efforts. Ugh.

——

I sanded to 150 on my ROS. I had no 180 ROS sanding discs left, so I sanded by hand at 180 grit. Figured that would be enough for a waterborne poly film finish.

I have a great spray gun but it’s been a decade since I’ve used it … much has been forgotten (like the fan adjustment. The documentation – Anest/Iwata – is so sparse as to be useless) so during set up I was getting a heavy center weighted pattern without a broad fan … “are the orifices obstructed?”. No. Finally got that figured out and got refamilarized wi the controls (!)... I was under extreme time pressure and rushed so working frantically.

Got one Sealcoat sprayed.
I was thinking I’d only need one, but it looks like it will need two. maybe I should have thinned the Sealcoat to a one pound cut(?) and done two coats of that?

There’s a few areas where it needs to be gone over: a coupe areas a little heavy with thick edge and one of these which boarders on a dry spot that didn’t get finish.
It left the wood grain raised/rougher than I though it would with an alcohol base so I’ll do light 220-320 sanding to smooth the nibs. I’ll need to do a second application and I’m hoping the 2nd coat of shellac will just melt in with the 1st coat for a seamless look.

I have drawers for another cabinet (not posted about) that are going to be finished just with shellac, likely two applications of Sealcoat. The case for that cabinet gets a Sealcoat of shellac inside and out, then General Finishes Waterbase Poly topcoat for the exterior only.

—-

Back to the drawers in question kitchen drawers that will be top coated with General Finishes Waterbase Poly/Flat.

Regardless of the above minor spraying issues – which I’m sure are easily correctable (I’m actually very good with spray guns but it’s been a very long time): unfortunately to my eyes the Sealcoat on these two drawers looks like completely terrible. It looks like crap to me.

Instead of popping the grain, deepening the tone of the dovetails, and enhancing the wood, it looks to have done the opposite: washed out the entire drawer and equalized all the wood. It looks to me like early era water base finishes would look. Uninteresting. Dull.

I’ve gone through all this trouble to do hand cut dovetails for a sightly dramatic look, accentuated and with some decent contrast. Instead, the Sealcoat seems to have obscured them. The reports I’d read online suggested the opposite. Again it looks like a nice, crisp, pristine drawer with uninteresting wood and partly obscured washed out looking joinery.

Not sure what to do at this point but I’m unhappy with the look, esp. with all the work, time, and struggle put into to these.

Do I need to sand the Sealcoat off? Not looking forward to that … maybe just sand the sides of the drawers since the fronts will get false fronts and no one will see the backs?
Would this benefit from boiled linseed oil first to pop the grain and deepen the end grain on the DTs, then Sealcoat, then the topcoat of water base poly? I didn’t do that because the reports I’d read suggested Sealcoat would do a decent job of that. It didn’t.

For comparison the pics attached show what the raw maple drawers look like before finishing, wiped wet with denatured alcohol. They look great.
The next pics show one of the drawers with Sealcoat next to another hand cut dovetail item which was recently finished with 3 coats of an oil/varnish blend (1 part BLO/1 part satin polyurethane/1 part OMS).The wood on the latter is different and is a softwood (I assume pine, I scavenged it). But still, and even though the pic is blurry, and disregarding the hue imposed by the oil/poly… the joinery is more accentuated.

I thought the Sealcoat would pop the grain and deepen the contrast but it’s failed completely to do that.

-- “It is the beginning of wisdom to recognize that most men are fools and knaves, but it is the end of wisdom to embrace that vision.” -Arthur Kleps

View Aj2's profile

Aj2

3577 posts in 2764 days


#9 posted 08-30-2020 10:58 PM

Real shellac doesn’t come in a can. I’ve been saying it for years the best shellac finish is multiple barely perceptible coats. 15 or more isn’t uncommon fresh shellac dries very fast esp when it’s super thin. It’s sometimes called polish but it’s really padded on. It will pop your joinery,grain and be very hard and durable. Much more then the can stuff .


These are the two I keep on hand.
I forgot to add I think your shellac was drying in the air if that drawer was sprayed. You could always wipe it down with a little alcohol denatured. Too give it some life.
Good Luck

-- Aj

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Rich

6385 posts in 1555 days


#10 posted 08-30-2020 11:49 PM

.

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

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Lovegasoline

176 posts in 1004 days


#11 posted 08-31-2020 12:01 AM

I’m not using Shellac as a finish, fine or otherwise (except for a final finish on drawers for another item which straddles the line between fine and utilitarian furniture … the fronts on the latter will receive a different top coat. This was all explained clearly in my post).

If you read through my OP, General Finishes Waterbase Top Coat is the finish.
The shellac Sealcoat is being used as … a sealcoat. To handle the grain raise and to add some grain pop (the latter which it has failed to do), maybe a touch of color (although that looks to be minimal) for use under a water white H20 finish.

This is the first time using shellac in a can for like 25 years … before the marketing of shellac was reconfigured and they ceased calling canned shellac ‘orange’ and ‘white’ and switched to ‘amber’ and ‘clear’. I’ve mixed plenty of shellac from flake from a variety of types. I can’t see why in the world ‘shellac in a can’ would be an issue for a sealcoat. Explain why it being in a can would be a problem. Date code was checked prior to purchase.

PS: For anyone following the discussion Rich has removed the content from his post above ^, consequently this post of mine now makes a little less sense (as it addressed what were for me erroneous ‘shellac as a finish’ issues).
Nonetheless the shellac in a can issue, re: Aj2 stands.

-- “It is the beginning of wisdom to recognize that most men are fools and knaves, but it is the end of wisdom to embrace that vision.” -Arthur Kleps

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Aj2

3577 posts in 2764 days


#12 posted 08-31-2020 12:47 AM

I guess we have different views of what we are trying to accomplish. My way of looking at it using shellac under any decent clear finish is not necessary. Unless your trying to control blotchy wood that don’t take stain evenly.
The other application for can shellac would be to block Old Douglas fir odors before painting inside a closet.
Rich and I have had this discussion about the purity of canned shellac. If you really have used fresh flakes then you know the difference.
I’m also not sure what grain pop means I don’t see anything in the drawer sides that really merits any effort. Most put all the efforts in the drawer fronts.
I won’t try to help anymore since I don’t know what your trying to accomplish.
Good Luck always

-- Aj

View Lovegasoline's profile

Lovegasoline

176 posts in 1004 days


#13 posted 08-31-2020 01:11 AM


I’m also not sure what grain pop means I don’t see anything in the drawer sides that really merits any effort. Most put all the efforts in the drawer fronts.
- Aj2

That’s fine Aj2. Thanks for your input.

The direction this thread has taken – in my eyes – is more complicated than the actual issue at hand.
The outcome I’m seeking is some decent level of contrast between end grain and the surrounding wood so as to accentuate what to my eyes is the beauty of dovetail joinery (some may find dovetails ugly so may differ on aesthetic issues and beauty). Also if possible, a little richness to the grain via some small degree of ‘pop’. Oftentimes water base finishes (or at least older incarnations in the earlier days) tended to be dull lifeless finishes on light woods.

Based on advice, the shellac Sealcoat was applied with the added function of sealing the grain and dealing with any grain raising/sanding.

Also and in my own (albeit limited experience) all shellac (even the premium offerings of ‘platinum’ or ‘super’ or ‘ultra’ blonds mixed recently from fresh flakes that have not been stored long in the raw flake state) adds some tone to the wood, it’s not only the so called amber, lemon, garnet, orange, etc. that add tone to wood. So I was hoping for a little of that as well from the ‘clear’ Sealcoat.

But the main thing was a little deepening of the end grain for a bit of contrast. However the opposite seems to have happened with the contrast between the end grain and the rest of the wood being reduced or no effective change.

The appearance of the wood with the denatured alcohol wipe is about what I was after.
The effect of the Sealcoat application has in my eyes diminished the moderate beauty that the drawers exhibited in
the raw wood state.

So, if one can imagine that drawers of this type in the future will come off the workbench with an adjustment dial which shall permit tuning in the dovetail end grain contrast … from extreme contrast to practically no contrast … then I’‘d like to set that dial around the level of the alcohol wiped DTs. Of course that dial does exist, now, in the realm of finishing treatments (and wood selection).

—-
To answer your question:
Grain pop as I understand it in it’s simplest form would be the accentuation of grain via contrast. So perhaps an issue of tonality or grain structures. This occurs differently in difference wood species and treatments. It can be a 2D situation or as in chatoyance it can simulate 3D effects.

The drawer fronts will be painted, blandly, so unlike most who put all efforts in the drawer fronts, doing so in this project will yield no results, nor would I want it to (the selection of hardware pull on the drawer front will merit more effort) and it would reverse the aesthetic effect. So in this case the aesthetics is the painted drawer front, the hardware, and the drawers sides (plus the drawer interior: the objects therein, the spacing and proportion, the textures, surfaces, and patterns). The drawer sides will also be in discourse to the rest of the wood in the room. It’s more downplayed. The exposed wood is in use in measured doses throughout the room, it provides a background and accent but in balance with other materials. In which case small details – like drawer sides – come into play. Hopefully there’s also something occurring on the level of proportion through the space and also, hopefully as I hone it in over time, the flow and movement of the eye – in speed, direction, punctuation, rest, activity, tight vs. wide focus … across surfaces and in time. There’s the factor of light as well … color has been reduced so slight shifts in hue and tone will become more prominent and texture (possibly pattern) will add another dimensional layer. I’m working with structures that are in place rather than redesigning from whole cloth, although there’s also been a little of that, so it’s a slow reshaping of forms over time to achieve a more harmonic balance.

So in this case, the sides of the drawers play a role. The DTs add pattern and the hue/tone of the end grain will be reaching out in communication with other small details in the space. A degree of contrast there will provide a point to slow the eye and focus … and connect it with other details in a slower background rhythm.

—-
The rationale for the use of shellac with the dovetailed drawers is described below …. however in addition to that I wanted to use it as a finish on other drawers and a case interior both from another piece of furniture. The latter will hold drawing supplies so I didn’t want bare wood for the drawers, I wanted a little protection from marks, dirt, graphite shavings, etc. and with fingers crossed even spills with a potential for being able to clean the drawers a little vs. unfinished wood, and due to the lack of egregious off gassing odor with shellac I thought it was a great candidate. That it’s easy to spray was also a factor. Expediency played a part.

-- “It is the beginning of wisdom to recognize that most men are fools and knaves, but it is the end of wisdom to embrace that vision.” -Arthur Kleps

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Lovegasoline

176 posts in 1004 days


#14 posted 08-31-2020 02:26 AM

Also, all my shellac in flake form are about a decade old. They are Liberion: Dewaxed Orange and Platina (Platinum Blonde/ Extra Pale Dewaxed). I decided it might be too old to use. I did mix up and use the orange (brushed on) on a temporary countertop underneath a General Finishes High Performance Top Coat as a test piece. It performed fine as did the GF top coat … it’s in use now on a temporary counter top that sees harsh use and the GF performs better than I imagined.

I too considered shellac in a can as infra dig … however I read some very promising things about Zinsser Sealcoat, esp. from authors who had no financial motivation in selling shellac or ideological dogmas to defend … in fact some touted its superiority for seal coat/barrier coat/washcoat purposes due to the mixture, the ease, price point, performance … and shelf life (how do they blend it to extend the life?). I can’t say as this is the first time using it.

I’ve only ever used shellac for sealing or toning wood under colorless water base top coats. I’ve never French polished anything. I’ve also used it as a sealer or utility topcoat on many items over the years where looks played no role.

-- “It is the beginning of wisdom to recognize that most men are fools and knaves, but it is the end of wisdom to embrace that vision.” -Arthur Kleps

View CaptainKlutz's profile

CaptainKlutz

3981 posts in 2460 days


#15 posted 08-31-2020 05:24 AM

Comments from an amateur FWIW:

- The very few times I use a WB top coat and want grain pop, one of my finishing schedules is: 1lb cut of amber shellac (from dewaxed flake only) on white wood, or 1lb cut garnet shellac on dark wood. Judge color change after one coat, use 2 if needed. Seldom do I use blonde or patina shellac to pop grain as it doesn’t have enough color.

- I usually have several different colors of shellac flake on hand and will test different colors or cuts on scraps before coating the project. Have even mixed different amber/garnet colors to achieve the tone desired. Tend to buy flake 1-2 pounds at a time, as have seen one shipment of Amber look more blonde, and visa versa. If shellac flakes are stored in cool place away from moisture (Tupperware with desiccant in humid area); they can last indefinitely. Testing if shellac has been contaminated with moisture is easy. Water cross links the shellac which forms a goop, snot, or jelly; like mass that will not dissolve in alcohol after couple days. What ever shellac does dissolve can still be used as is, just note the cut will be less than planned.

- IME Satin gloss top coats hide or diffuse the grain, compared to gloss finish. To get any serious grain pop with satin finish on white wood, you need some serious color addition. Oil can work sometimes, but IME you need to use highly diluted amber (or brown) dye stain as ‘wash’ coat, and sand back top surface to desired wood color. Then spray 1lb cut of light blonde shellac as sealer to prevent WB carrier from pulling dye out of wood.

- Always test, test, and test again; any new finish schedule before using on completed project. Finishing takes as much time as building, if not longer on large builds for me. I will spend several days testing out any new finishing schedule, or checking out new batch of lumber with unusual colors when using an existing schedule.

Best Luck getting the look you want.

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

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