A couple questions on Sanding Sealer-
If i want to STAIN a project, I stain first, then apply sanding sealer, then topcoat correct?
If painting I put Sanding sealer then color, then top coat if desired?
Okay...last one... If painting...Sanding Sealer >Primer>Color>Topcoat- Is sealer needed if using Primer such as Bin Shellac Primer?
#confused
Thanks
D
Apply sanding sealer first before staining. This will seal the pores and make sanding easier with less potential "scoring" of the actual stain that one might get when the fines get caught up in the sanding paper. Similar to a stain pre-treatment/wood conditioner the sanding seal will minimize blotching on softer woods, and provide for a better, more uniform stain.
You may not need a sanding sealer at all depending on the species and what you want the finish to be. If the wood doesn't have undesirable pores to fill and isn't prone to blotching, why use it? My advice is to buy enough material so that you have some scrap to try a finish schedule that you haven't used before. That way, you will know what you are getting. I have seen dozens of posts from people who messed up a project because they tried a new method without experimentation first.
This. Apply first.Quote:
Originally Posted by Al Launier
I never use sanding sealer. IMHO it's a waste of money. If I need to use a sealer, I use Sealcoat shellac. For the finishes I use, that product works across all of them.
If painting, I use primer first, not sanding sealer. Generally, I use BIN pigmented shellac primer, but sometimes you have to use primer specific to the paint going over it. And sometimes the paint is it's own primer. In any case, I don't see a place for sanding sealer under paint.
John
David,
See the thread entitled "finishing question" below. I'm with those who say that you rarely need to seal wood before applying your finish coats. Sanding sealer is a thin varnish with an inorganic soap (stearate) in it to lubricate sandpaper. The stearate may interfere with bonding of finish coats, especially some polyurethanes and water-based finishes. IMO routinely using sanding sealer is "received wisdom" that often has no solid rationale. On the occasions when you do need a seal coat or barrier coat consider using dewaxed shellac (e.g., Zinsser Seal Coat) as John recommended above.
Doug
The first rule is to keep it simple.
In general, stain first then apply coating whatever it is. Sanding sealer can be used but it is not necessary. In a production environment it gets used as it is quick drying and speeds work flow. However, it is not a generic product. You must use the one that matches the top coat ie from the same manufacturer or face problems as outlined by Doug. I don't use one at home but have used them in production shops. I stick with the same product all the way through. There are no compatibility issues with this approach.
When staining, you get the best colour by applying the colour directly to the timber. This make your colour clear and highlights the timber itself. The principle here is that you stain to enhance the appearance of the timber. If you seal the surface first, the colour goes uniformly over the surface like a weak paint rather than reacting with the timber as a stain. This hides the grain to some extent and creates a quite different appearance that doesn't really enhance the timber. If your timber is one that goes blotchy, either don't stain or you may have to sacrifice clarity and seal first. For me, if a timber doesn't take stain well, I don't used it in that situation but others here have techniques for dealing with blotching.
When painting, your paint manufacturer should supply a primer and top coat that match. This is a coating system. The primer should be readily sandable. If it is not, change to a manufacturer that makes products that are good to use. With a good primer/topcoat combination, sanding sealer is irrelevant. Cheers
Sounds like the sales guy at my paint store made a sale because i was un informed.....i never used it before and thought i must have been doing something wrong... My goal is to practice and learn how to make some glass smooth finishes on my wood projects.. ie table top, book shelves, etc... i thought the sanding sealer was a component i was missing. I have an auto body background.. you know.. prepare metal, prime , using a sanding primer, paint, clear coat...WALA Done.. LOL
Since you have an auto painting background, you are set for painting techniques. You just don't need as many stages. High build primer, sand, colour is all you need. Clear over if you feel like it or the system demands it. Cheers
This is a standard procedure dependent on the wood being used.Quote:
Originally Posted by David Ruhland
Sanding sealer may not be needed dependent on the topcoat being used.
Sanding sealer may have to be applied first to control blotching.
No, when painting you use a primer that works in conjunction with your topcoat. Not all primers are created equal and never use a soft primer with a hard topcoat.Quote:
If painting I put Sanding sealer then color, then top coat if desired?
No. See above. Typically when using a quality product you will need Primer matched to Coloured Topcoat. Personally I go the the manufacture and ask what they recommend and follow their procedure. I mix don't mix brands, to hard to figure out a problem by mixing up product lines.Quote:
Okay...last one... If painting...Sanding Sealer >Primer>Color>Topcoat- Is sealer needed if using Primer such as Bin Shellac Primer?
which type of sanding sealer? For oak and other open grain woods, there is a paste style sealer that fills the pores in one coat and leaves a thin residue on the wood that must be sanded off. It leaves oak as smooth as glass with no open pores. Then there is a sanding sealer like Bull's Eye sanding sealer and that is nothing but UNWAXED shellac and denatured alcohol. It is far too thin to fill the pores in oak with a single application. Any finish can be used over the shellac sanding sealer because it does not contain wax. Using waxed shellac limits using some finishes. There is another water based sanding sealer from Min wax. I don't know much about it, I have never used it. Years ago, I wanted an ebony finish on a pine end table. I stripped and sanded the table. Painted it with black permanent India Ink and a very fine grit light finish sanding and then formby's tung oil finish. My Dad who had been a cabinet maker, thought it came out great. And then indicated that I spent more time making it look like something than if I had built the table from scratch with proper materials.
I don't use it. IMO its not necessary and in cases where I might use a sealer, I use shellac (such as sealing knots prior to painting)
I suppose you could use it if you were concerned about blotching or maybe on a very resinous wood.
The BIN shellac based primer is excellent. I still pre-coat the knots with shellac for insurance.
Aren't many of the sanding sealers (and primers) basically shellac?
The sanding sealer I have used has been acrylic. Most gets sanded off before applying stain.
There are many types of sanding sealers...
Some are meant to prevent oils in the wood from bleeding into finishes or causing finishes to not harden properly (Shellac is fantastic for this duty)
Some are made to hide grain features and make stains and dyes work more uniformly - to prevent leaving blotches and funny ugly shadows, dark pores, etc...
Some are made to provide a slightly flexible coating so that a final coating won't crack or peel when the wood expands and contracts (vinyl sealers are used under lacquer for this)
etc....
I use both shellac and lacquer based sanding sealers on wood turnings, depending. I usually thin, depending on the wood and the reason for the sealer. (Sanding sealer appears to be thinned finish anyway.)Quote:
Originally Posted by Stan Calow
I don't stain so I have nothing to say about that except if I did stain I'd first try it both ways on sanded pieces of exactly the same wood, both side and end grain. I dislike unpleasant surprises.
I may be a bit different from the rest in opinion and usage. I bought a Furniture Medic Franchise about 3 years ago and started refinishing items where I had no reference as to how they had been used.
For my own past projects I rarely used sanding sealer and/or shellac and was using mostly solvent based stains and finish.
One of my first paying jobs was to refinish a table top. I was only sanding and refinishing the top. I decided to use shellac as a barrier and a waterborne finish (General Finishes pre-Cat urethane) as a top coat. I had contamination problems which caused crazing. In retrospect, I think I had sanded through the shellac in spots which casused or aggravated the issue. General Finishes told me that I had to use GF sanding sealer not shellac since teh Pre-Cat shrinks as it cures. I swithcehd to that and was able to seal in the contaminants. it took multiple coats but it worked. i suspect the shellac would have worked too.
Anyway, as a result, I now always apply stain (GF water based), GF sanding sealer and then finish (GF waterborne). I almost never have trouble. The sanding sealer also seems to have more solids so it fills faster and sands very easily. I had trouble once (on a table). I use a lot of extender since it is so dry in CO and last spring i did a table and it was a litle more humid. I noticed my finish coat took a while to dry. or at least skin over. I think the extended drying time allowed some contamintates to interact and I had some trouble. I swithced from 15% extender in my sandig sealer to 0% and sealed the contamination. All anecdotal but I am a fan of using sanding sealer, at least for refinishing. I also use it after stripping and staining.
If I was doing only new construction I may change my ways but it is a habit now. The sanding sealer is less expensinve and I think it is a great prep for the finish coats.
Gary, what shellac did you use under the GF Pre-Cat lacquer? I've used SealCoat shellac with the their Pre-Cat lacquer (the one with the red label) w/o problems. GF will always tell you to use their sealer; pretty much just like every other finish manufacturer.
John
There are many variation on what is considered a sanding sealer not to be confused with grain filler. Getting a glass smooth finish should have been part of the original questions and is dependent on wood type. You won't get a glass smooth finish on Red Oak unless you use a grain filler. Not true on maple. In your post you didn't mention whether you were using WB or solvent. There are specific sanding sealers, shellacs of various formulations and diluted topcoats used as sanding sealers and its typically at the users discretion/experience. Broad based, non definitive questions like you asked will always get you a smash smash of answers like above.
Quote:
Originally Posted by John Kee
I am simply practicing and learning for now using oak. I have a fireplace mantle I want to paint in the future and don’t want the grain to show through and am hoping to achieve a smooth glass like finish I understand I need to use a grain filler and have a can of Old masters grain filler in my arsenal. The slick salesman sold me some oil based sanding sealer Ultimately I want to topcoat with the old masters Armour Clear
I am learning... slowly..... thanks for all the great info so far
David,
Just so I am clear what you are asking for...
Is it this:
You want a mantle clear coated - but you don't want the grain texture printing through the finish?
Or this:
You want the mantle painted some color (such as White) with paint and you don't want the wood grain or texture showing through?
If you want #1 - Mantle clear coated so you can see the wood but no grain texture printing through the finish..
Consider either some sort of dark paste pore filler or a clear pore filler product. Fill all the pores and sand back carefully. Red oak literally has bottomless pores - so you will have to do multiple rounds of pore filling and sanding back to get them all.. Then stain as per whatever makes you happy. At that point - you only need a "sealer" if your finish dissolves your stain or pore filler..
Next is the tricky part - as most every high build varnish, urethane, or epoxy sort of product will leave witness lines where you sand through one coat into the next... Power buffing helps this a lot. The general procedure is to apply multiple coats to a total finish build of 0.020"+ and then level and sand going through grits up to 2,000 or so, then machine polish with a buffer.... Interestingly enough - Ace interior varnish has a reputation of being well behaved when spraying (for a varnish. ;) )... That's an option since you already have spray background...
If you just want to paint it white or some such... Well - paint the wood with a good high quality PVA primer. Skim coat it with drywall compound. Sand back smooth... Repeat skim coating and sanding back as necessary to get all the pores filled. Then prime with a quality interior primer and paint.
Quote:
Originally Posted by Gary Muto
Gary if you do a little research you will find that products like Zinnser Sealcoat and other other shellacs combos sometimes do not play well with urethanes, especially if you use a heavy coat. Just a little heads up to add to your knowledge base.
I've never had a problem with Sealcoat under WB polyurethane, or any other finish. I'd be very interested to see any of the references you found. Thanks.Quote:
Originally Posted by John Kee
John
I used the Zinzer dewaxed shellac. I don't think it was the shellac. I think OI may have sanded through it though. I also used a 1-/2 lb cut so maybe it was too thin to begin with
Previous reply was to John T.
John K.,
Thanks for the info. Genereal Finishes position on it was that Shellac was not compatible with their Pre-Cat Urethane. I recall having the impression that Tom was implying not to use it under any catalyzed finish but i don't recall him specifically saying that.
He also told me that the General Finishes sanding sealer is a Pre-Cat formulation. I found that surprising since i didn't think it would be compatible over a variety of finishes. In my limited experience it does work well but on 2 occasions I had to apply multiple coats to seal in some contamination
John Kee did indicate "especially if you use a heavy coat" which as been mentioned as sometimes causing issues with water borne finishes both here and elsewhere. I'm guessing that would be the case when the person applying the shellac isn't knowledgable or experienced with applying shellac.Quote:
Originally Posted by John TenEyck
Thanx for the clarification Jim, I have a really hard time doing peoples research for them. Here's one reference: https://www.targetcoatings.com/faq/ Also if you read the TDS from General Finishes they don't recommend anything but their sealers and when you want to vary from their recommendations to contact them. People often view that if they don't have a problem no will have a problem, unfortunately the finishing world and the finishers themselves vary too much to state something like that as gospel. I've applied Zinsser Sealcoat under a lot of different clear coats, sometime you win sometime you lose.
Quote:
Originally Posted by John Kee
Thanks for the reference, John. I'm actually surprised TC's said you can use shellac in any form. Kudos to them. Most manufacturers, as in your GF reference, only recommend their own sealer.
If you look at a can of SealCoat it says something like "Safe under all finishes". With the finishes I use, including several from GF, I've found that to be true. Everyone should test any new finish recipe for themselves prior to using it on a project.
John
About 12 years ago I starting researching Zinsser Sealcoat and polyurethane problems 0n Woodweb, back then I actually think Zinsser warned about possible issues with some urethanes. The common consensus was it was something in the solvent mix. 10 years has been a long time in finishing industry, it sounds like a few ingredients might have changed in the Zinsser mix. You are right John T always do tests to avoid surprises. Target also make a WB Shellac, I experimented with and it works but doesn't come close to the pop in wood grain that an alcohol base shellac brings.
For others the actual quote from Target Coatings.
"Yes. You can use Zinsser SealCoat underneath any EMTECH™ water based sealers or topcoats. However, we stress that you reduce the SealCoat with denatured alcohol at a ratio of 1:1 before applying SealCoat as a bed coat or intermediate seal coat. Full strength Zinsser SealCoat may create a fine craze or crackle effect underneath high pH water based finishes. To prevent this effect we h3ly recommend that you, 1) Reduce the SealCoat, 2) Apply thin coats, averaging 1-2mils in wet film thickness, 3) Do not exceed two coats of reduced SealCoat prior to applying EMTECH™ finishes."
The Sealcoat Web page is interesting reading:
About SealCoat™ Universal Sanding Sealer
Save time when finishing porous woods by starting with Rust-Oleum® Zinsser® Bulls Eye® Sealcoat Universal Sanding Sealer. This high-building solution seals the wood to create a surface that can be easily sanded. Contributes to an ultra-smooth final finish.
- Compatible with ALL clear wood finishes
- Great for sealing ALL interior wood, including floors
- Dries lightning fast - can be sanded & recoated in minutes
- Does not darken or yellow with age
- Easy clean up with alcohol or ammonia and water
- Gives extra beauty & warmth to water-base polyurethanes
- Can be used as a pre-stain conditioner for pine and softwoods
- Can be used as a bond coat under new finishes – adheres to any existing finish
That's a pretty bold statement to say it is "compatible with ALL clear wood finishes". It has been true for the finishes I use, but could easily imagine there being exceptions. Test.
For Best Results
Apply two coats to improve film build and give added depth to the final finish.
Available Sizes
- Quart
- Gallon
- 5 Gallon
The primary reason I like Sealcoat is because it doesn't raise the grain like waterborne sealers tend to, and because it really highlights the grain. I've tried MinWax's and GF's WB sealers. I can't remember which one, but one of them was terrible for grain raising. I think that's what caused me to look at Sealcoat in the first place. I love waterborne products, but there is real need for improvement in the sealers. If someone has used one that doesn't raise the grain, please post it. Thanks.
Another way I use Sealcoat is to create a bond coat over an oil based stain so that I can use a WB finish. GF and others say you can apply their WB topcoats over a well cured OB stain. I haven't found that to always be the case. A light sprayed coat of Sealcoat (or rattle can shellac) has always worked. As always, test.
John
Rustoleum has a very clever marketing department. Marketing typically exaggerates the good qualities and completely forgets the marginal properties. John T I have found in my 60 years on this beautiful planet bullsh!t usually baffles brains, that is until step you right in it and go up to your eyeballs. Like you said before test, test test
Its a good idea in general to use a coating system that works for oneself and get experience with it. Repetition is a good teacher, especially if notes are kept as to what one does each time including what the weather was like. Cheers