2 questions about clear poly finish

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Old 06-06-12, 05:09 AM
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2 questions about clear poly finish

#1) Back in 2008, I used separate cherry stain and clear poly on my blanket chest, coffee table and two end tables. The coffee table gets alot of use. I am thinking of giving another protective coat of clear poly before any damage becomes apparent.

Do I need to lightly sand it and if any stain gets removed, re-sand the whole thing or touch up the removed areas or can I just clean it and re-apply a coat of poly for further protection? The lid of the blanket chest needs re-sanded and re-stained since the dogs' toenails have scratched it up so I'd like to do both at the same time.


#2) I just built two toy boxes that will get alot of use from little ones. I had a can of pecan stain and poly in one that I mixed really well and had enough to do both boxes, they are currently on the 1st coat and I think that 2 coats will be enough. Can I then apply another coat of just the clear poly on top of the 2-n-1 product for additional protection or can you not mix the two together?

Thanks,
kjh9835
 
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Old 06-06-12, 05:14 AM
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Yes, you should sand it well, using 220 grit sandpaper, or if you are using the 3M Sandblaster products, like their sanding sponges, the fine 180 grit. Hopefully no one has applied any furniture polish to the furniture, since this can affect the adhesion of any future coats. (google polyurethane fisheye) You can always apply additional coats of poly over the top of Polyshades. Again, you would sand before each coat.
 
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Old 06-06-12, 05:16 AM
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It's always best to sand lightly between coats of poly - it promotes good adhesion. Sometimes when raw wood is exposed on a piece of sealed wood, the stain can be touched up. If you sand thru the stain, I'd try touching up the stain first, if that doesn't work, it won't add much to the stripping process.

It's always a good idea to apply a clear coat of poly over tinted poly! That gives the color coat some protection. Without it, as the poly wears off - so will the color Just make sure that both the tinted poly and clear are of the same base [water base with waterbased, oil with oil base]

X brings up a good point - if there is any wax on the piece it should be removed prior to sanding!
 

Last edited by marksr; 06-06-12 at 05:17 AM. Reason: add info
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Old 06-07-12, 10:55 AM
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Thank you both for your replies and advice. I have used furniture polish on the coffee table, etc so I'll be sure to sand it well. I have a variety of grits of sandpaper both for the belt sander and the small hand sander so that's not an issue. I also found the nearly empty can of cherry finish I used previously so I can reapply that stain once the sanding is done and get another can if needed.

I've put two coats of pecan stain on the toy boxes and fixed some drips that I didn't catch. One large drip was on the inside of the smaller box so I sanded it off and did two more light coats to fix it. I can see the difference but it really looks like its just the wood grain and since it's inside, it doesn't really matter. i doubt the recipient will notice it.

I'm thinking I may make two more toy boxes.....it's the first project I've done "on my own" since my husband does not like these types of projects. He'd rather fix mechanical stuff than do woodworking but I've enjoyed making something useful much cheaper than those already on the market.

Thanks again,
kjh9835
 
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Old 06-07-12, 11:05 AM
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I've enjoyed making something useful much cheaper than those already on the market
Usually better built too! That's my biggest complaint with a lot of store bought stuff - cheap materials
Sanding doesn't always remove the wax/polish - sometimes it will push it deeper into the wood
It's best to remove the wax first. Paint thinner works well, just make sure you turn the rag often or change rags if need be so you don't just move the wax around. If you use paint thinner - proper rag disposal is very important!! Put them outside in a metal bucket w/lid or a bucket of water.
I think ammonia might also remove wax but I don't know for sure.
 
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Old 06-07-12, 11:08 AM
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On the "fisheye" issue (I just read about it), here's what I found:

"There are three ways to deal with silicone contamination: Wash the wood many times with a strong detergent or solvent such as mineral spirits to thin and remove the oil from the pores; seal the wood with shellac to block the oil from getting into the finish; or add silicone (“fish-eye eliminator”) to the finish to lower its surface tension so it will flow out level."

So if I don't know for sure if it will appear, instead of just sanding and sanding, I need to do one of the above methods before trying to reapply the clear coat and/or the stain. I have mineral spirits so that would be my first choice. How do I know if I've washed it enough to remove the silicone build up from the furniture polish?

kjh9835
 
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Old 06-07-12, 11:15 AM
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Usually a white rag will turn color a little after it's removed wax/polish.

While I've used 'fisheye medicine' in paint sprayed on cars and such, I've never seen a need for it in residential work. About the worst that will happen is you'll need to resand and reapply the finish coat. As long as you make a decent effort to remove the wax - I doubt it will be much of an issue.
 
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Old 06-07-12, 05:06 PM
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You are mentioning that you might apply "another coat of stain". If the surface is sealed with polyurethane (or poly mixed with stain) applying stain will not help since it will not be able to soak into the wood. It will simply sit on the surface and if it is allowed to dry, then you come back and brush poly over it, the solvent in the poly will just smear the stain around.
 
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Old 06-07-12, 08:40 PM
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Sorry, let me clarify on the coffee table/blanket chest:

Lightly sand the tops with 220 grit sandpaper, clean really well with mineral spirits and a white towel to remove any build up of furniture polish.

If while sanding and cleaning, I notice that the cherry finish is actually being removed, I will continue to remove it all and wipe it down before re-staining and re-applying the clear poly coat.

If while sanding and cleaning and none of the cherry finish gets removed then I can just wipe it down and re-apply the clear poly coat for protection.

I think back in 2008, I did three coats of cherry stain and one or two coats of clear poly but I can't remember how many of each. I don't want to remove so much of it that I have to refinish ALL the pieces so they match, I really just wanted to add more protection to the top of the coffee table and maybe do the blanket chest to get the scratches out of it.

Or, maybe I'll just put a table runner across both pieces and leave it at that?

kjh9835
 
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Old 06-07-12, 09:03 PM
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You have the order backwards.

Number one, FIRST remove any residue from wax and/or furniture polish with Naphtha and rags. Follow that up with a light sanding with 220 grit sandpaper. You will not sand through the finish with 220 grit sandpaper unless you would happen to push really hard on a corner or edge, so be careful around edges not to sand too hard. The idea behind sanding is not to remove the original coats of finish, it is simply intended to remove any impurities and dull the surface slightly so that the next coat of finish can bond well. So don't rub it like you're trying to polish your boots... the key word is "LIGHT" sanding.

Number two, you would then wipe any dust off with a tack cloth and then apply an additional coat of finish.
 
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Old 06-08-12, 08:19 AM
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Light sanding is right - I call it 'scuff' sanding. All you're doing is roughing up the surface a little bit to create nooks and crannies into which the wet polyurethane can flow to help create a better mechanical bond between the layers of poly. In and of itself, polyurethane does not adhere all that well to itself so you can get peeling of the layers if you do not scuff sand between coats.
 
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Old 06-09-12, 08:44 AM
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Thank you both again. Ended up having company yesterday and only got the two toy boxes completed. I will prob. start on the chest/coffee table tomorrow as I have some sewing/mending to do for dtr who came to visit (at least she didn't bring laundry...lol).

kjh9835
 
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