# Why sand stained wood when a bonding primer can work?



## ratherbefishin' (Jun 16, 2007)

A light sanding will let you know if any of the existing finish, probably poly, is loose or flaky. If you're lucky enough that it's all still well adhered after 18 yrs, you'll at least be giving the primer a little more "tooth" which will insure a long lasting paint job. You picked a great paint, so stick with BM and use the Fresh Start enamel underbody primer.
If you prime before patching holes and cracks, you'll need to spot prime those areas before topcoating. I usually fill first with MH Ready Patch, then prime, then topcoat.


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## Brushjockey (Mar 8, 2011)

Because on top of a stain is a clear hard finish, like a varnish or poly. You are not going over raw wood. While those paints say no sanding needed, anyone with any experience knows that it is easy to write that on the can, Sanding improves adhesion. Period.


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## ebaygolfer (Jul 30, 2011)

so you fill (caulk cracks, spackle holes) first, then prime, then SAND, and then top coat twice? 

In this case the entire house (2002 Richmond Home, approx 3,500 sf + full finished basement) has stained wood throughout, including doors, windows, crown, trim & baseboards, built in bookcases and shelving, etc...and it's all in immaculate condition! It has yellowed over the years and even though pristine shape, it all makes the home appear well...dated. 

The high crown molding and windows must be worked from a 24' ext. ladder and I've convinced myself that the right primer would...could...possibly enable me to skip sanding way up high and just prime & paint it out with little, or no real mess to vaccume up.

Thought it might work best to group doors together to work on 4-8 at a time, layed out on saw horses to prep and use the airless on them. Quicker, but with Impervo is it necessary? Doesn't Impervo level real well when drying? If so the finished look from brush and roll should appear similar to spraying (assuming the painter knows something about painting). Thanks for your comments and BM FS tip. Indeed I'll use #217 for wood even though it's the clear-poly getting primmed sounds like it makes for a great enamel top coat base for Impervo. Many thanks,


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## Brushjockey (Mar 8, 2011)

Id sand for adhesion( scuff sand) , prime. Then you will see all the areas that need caulk and filled. If there is a lot of filling ( shouldn't be if the original guys filled the holes, but often is) might require re prime - or a 50/50 prime . Then finish.


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## Brushjockey (Mar 8, 2011)

The sand doesn't have to be heavy, just break the gloss so the primer can grab. For that hi work , just give it a good once over with a sponge and do it. Work a little harder for insurance on the most likely to get wear areas.
Are you using Oil Impervo or waterborne?


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## ebaygolfer (Jul 30, 2011)

Brushjockey said:


> Because on top of a stain is a clear hard finish, like a varnish or poly. You are not going over raw wood. While those paints say no sanding needed, anyone with any experience knows that it is easy to write that on the can, Sanding improves adhesion. Period.


Of course I understand that *adhesion is enhanced*... however, how much adhesion is necessary on crown molding (9' ceilings) or high windows where virtually no human touch will pass again until it's re-painted.

I'd rather prime and paint... especially when I'm up on a 24' ext. ladder. I still think the gripper product or its equiv. will work fine for this project as I plan to hit all but the really high stuff with at least a between coats finishing pad prior to priming...and I'm using oil based BM FS 217. Thanks for the reminder about adhesion. :wink:


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## ebaygolfer (Jul 30, 2011)

Oil Primer, don't know for paint. Any advantage using one over the other? Personally, I like working w/oil so I'll most likely use oil.


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## Brushjockey (Mar 8, 2011)

Both have pros and cons. I have been switching to waterborne- easy to work with ( has learning curve though) , Had more flex over time- won't crack. 
Doesn't yellow. 
Oil is harder , easier to work with in a different way , classic look.


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## ebaygolfer (Jul 30, 2011)

Good point. Oil will crack and chip over time but I think it will cover poly and stain and prevent future tannin bleeds. I'm not convinced waterbourne's will do the same on 18 yr old polished, yellowed stained wood trim, doors and windows. I'm not sure if I really need oil Impervo but an oil primer should work fine for either one...and you're right again...E Z Clean-up! Thanks for your thoughts on this.


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## Brushjockey (Mar 8, 2011)

If it is varnished, and a hardwood- tannin shouldn't be a problem.
And the oil prime would most likely take care of it if there was.


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## jsheridan (Jan 30, 2011)

Ebaygolfer, unless you're working on a low budget job, relying on bonding primer exclusively for bonding is not recommended. Sanding not only provides "tooth", as already stated by 'fishin, it dislodges any non bonded clear, and it provides for a smooth finish appearance wise. As I said in another post, clear coats mask blemishes that paint will not. You may need to do so much sanding after priming that you will absolutely need reprime. When you're on the ladder, sand as you go, dust off, and prime, move, repeat. Take a pot hook up with you. Now, if by "217" you mean Alkyd Enamel Underbody as primer, that's a wrong choice, as it's not recommended for surfaces requiring bonding, or bleeding woods for that matter. Personally, if you're worried about tannin, I would use Zinsser BIN shellac, and that would solve all your concerns. I personally don't trust any latex products to block tannin period. And, I'm growing leery about oil for the same, as I got burned by cover stain on two issues where I wouldn't have been before. If you want to go oil, you need All Purpose Alkyd Primer#024. 024 is rated excellent for bonding. Finally, one of the things with stained/clear work is that it hides the nail holes. If you putty prior to priming, without the aid of the primer illuminating what needs filling, you'll be doing a load of it as well after priming. I have never really found a need to fully reprime after putty, as two coats of finish, interior, will sufficiently cover without flashing. The prep and priming of these surfaces is the single biggest factor in the future life of them with regard to appearance and integrity, don't skimp.
BTW, I can't seem to put a finger on what you're using for finish. You mention semi-gloss and Impervo, no such animal. Can you pin point?


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## ltd (Jan 16, 2011)

all right here we go first off wash any wood that might have any dirt ,and grime ,lemon pledge ,liquid gold .make sure to rinse clear:yes: .ok now sanding ,i'm not talking bout saw dust here .your only running your hand over every inch deglossing i mean its not a big deal. i like cover stain from zinsser ,use a nylon polyester brush it leaves fewer brush marks:yes: .now you can see were you need to caulk and fill any nail depression ,i like ready patch for this .ok your going to love this ,sand again:huh: very lightly do not remove any primer again just run your hand down it once very fine sand paper.im not familiar with ben moore paint but i do no its excelent .id go with 2 coats sherwin williams pro classic or ppg manor hall .imho use the 100% acrylic latex


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## ebaygolfer (Jul 30, 2011)

jsheridan said:


> Ebaygolfer, unless you're working on a low budget job, relying on bonding primer exclusively for bonding is not recommended. Sanding not only provides "tooth", as already stated by 'fishin, it dislodges any non bonded clear, and it provides for a smooth finish appearance wise. As I said in another post, clear coats mask blemishes that paint will not. You may need to do so much sanding after priming that you will absolutely need reprime. When you're on the ladder, sand as you go, dust off, and prime, move, repeat. Take a pot hook up with you. Now, if by "217" you mean Alkyd Enamel Underbody as primer, that's a wrong choice, as it's not recommended for surfaces requiring bonding, or bleeding woods for that matter. Personally, if you're worried about tannin, I would use Zinsser BIN shellac, and that would solve all your concerns. I personally don't trust any latex products to block tannin period. And, I'm growing leery about oil for the same, as I got burned by cover stain on two issues where I wouldn't have been before. If you want to go oil, you need All Purpose Alkyd Primer#024. 024 is rated excellent for bonding. Finally, one of the things with stained/clear work is that it hides the nail holes. If you putty prior to priming, without the aid of the primer illuminating what needs filling, you'll be doing a load of it as well after priming. I have never really found a need to fully reprime after putty, as two coats of finish, interior, will sufficiently cover without flashing. The prep and priming of these surfaces is the single biggest factor in the future life of them with regard to appearance and integrity, don't skimp.
> BTW, I can't seem to put a finger on what you're using for finish. You mention semi-gloss and Impervo, no such animal. Can you pin point?


Well thank you for the details...I'll be using Satin Impervo and All Purpose Alkyd Primer#024. Will lightly sand before priming, then I'll fill holes and cracks, then lightly sand and paint 2 top coats. You and others have been helpful and greatly appreciated. Many thanks!:thumbup:


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## mustangmike3789 (Apr 10, 2011)

ebaygolfer said:


> Of course I understand that *adhesion is enhanced*... however, how much adhesion is necessary on crown molding (9' ceilings) or high windows where virtually no human touch will pass again until it's re-painted.
> 
> I'd rather prime and paint... especially when I'm up on a 24' ext. ladder. I still think the gripper product or its equiv. will work fine for this project as I plan to hit all but the really high stuff with at least a between coats finishing pad prior to priming...and I'm using oil based BM FS 217. Thanks for the reminder about adhesion. :wink:


as you may already know, a profile is a series of peaks and valleys that will aid in bonding. as paint drys/cures it will shrink and pull away from the profile, leaving the finished film attached at the higher points in the peaks and the valleys empty. without this profile you could experience premature peeling as the paint cures and moves over time. some paints will shrink more than others depending on the amount of solids, this is why you will see recommended application methods such as wet fillm to dry film thickness, min and max profile size, and proper surface prep listed. too mush profile can be as bad as too little. if the profile is too high/deep for the given coating, the peaks in the profile will break through the dry film as it cures and expose the substraight to moisture and contaminates. this condition can be easily spotted on steel when pin point rusting occurs. relying on a bonding primer alone over a hard glossy surface will probably result in a shorter life expectancy of the paint. at least 75% of all premature paint failures are due to improper surface prep.


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