12

For starters, I am going to guess you used a water based urethane instead of an oil based product? I have never seen a good oil based product react as you described to simple spills. I have seen some damage caused by very hot items being placed on a urethane finish, but normally, liquids will bead up and not penetrate the finish. Even though the water based ...


8

It's all about adhesion. When you recoat after 2 hours you get a chemical bond between layers. If you let it go longer than that, you need to wait 24 hours so it's hard enough to sand and get a mechanical bond. I sand before the final layer. That gets it smooth without danger of sanding through.


7

To elaborate a little more. When you apply a finish like poly or even paint, it doesn't just instantly go from a liquid to a solid after an hour or whatever the dry time is for the product. When it's exposed to air it slowly starts to solidify. As this happens the physical properties of the finish change. Most importantly it's workability changes. If you ...


7

I had two floors to do once and between coats I used a broom with 3 bits of fine sanding paper taped to the broom head - cheap, cheerful and effective... Also, had to punch down the floor brads (nails) so they were below the surface... Those floors came up magic but also vacuumed after sanding to remove the dust...


7

You could use a hand-held orbital- like you mentioned the biggest downside is time. But you're correct, sanding between coats of poly isn't stripping an old floor- it's just scuffing up the previous coat of poly in preparation for the next one. Even easier for this step though would probably be a pole sander- like the kind for drywall seams. Use a fine ...


6

Doesn't make any difference, really; the question is number of coats per surface, not order they're applied in. The thing to watch out for is that there will be a tendency for drips to run down the edges and onto the other face. You may want to use masking tape or other techniques to guard against that, though going with multiple thin coats rather than ...


5

When I looked into this question in the past, I reached the same conclusion as JayL, plus one additional handy rule: If I can smell the finish at all, it is not completely cured yet. So when my thinned poly coats feel cured to the touch, I lean in and take a deep breath. Usually there will still be a faint whiff that lasts up to a couple more weeks.


5

First of all, I'm assuming you already sanded the surface smooth enough before you started. If you put polyurethane on a rough surface you will get a rough finish. Second, as @keshlam says, make sure there is no dust at all on the surface before you apply the finish. A slightly damp cloth can help pick up anything remaining (but make sure the wood is dry ...


5

The first coat of finish will raise the grain of the wood, so you need to sand it down with some sandpaper (220 grit or so) before you put on the next coat. This is mentioned in the directions.


5

Depends on the quality of the existing finish... if it's as flat as you want it to be, then I'd kiss it with 150 on a pole sander. Link for illustration purposes only: there are many out there... If you need to knock down blobs/ runs/ etc, then start with 120 on the handheld random orbit sander. Work your way up to 150/220. Vacuum and then wipe with a ...


4

Lots of good answers here. I was a finisher in a cabinet shop for many years and this is how used to do it. Avoid anything with silicone to get on your hands or near your wood project. It causes fish eye dimple defects in your clear coat and will ruin the finish. Such items with silicone include lubricants, water repellent sprays, etc. Wash your hands ...


4

It simply means that the edge of the finished area should not be allowed to dry out, so you're not putting wet polyurethane over dry.


4

If I may add something here: they sell polyurethane that is pre-thinned. One brand I've used is Min-wax Wipe-On Poly. It's intended to me wiped on with a rag and I've never had any issue with bubbles. This is actually all I use any more. I have not examined the cost though; it could be that this product costs more than simply buying poly along with a ...


4

The drying times on the can are usually very optimistic in my experience. They sometimes state the drying conditions the times are intended for, like 78 ºF and <20% humidity. If you are colder and/or more humid you will have to wait longer. Definitely do not sand if the finish is tacky. There's no harm in giving it extra time to dry. At this point I ...


4

I normally would not recommend thinning urethane. If you have a new can of fresh urethane, it should be ready to go. I would try to apply it thin rather than a thicker coat. If you feel you really need to thin it, just slowly pour some in another container and add a small amount of thinner at a time. Stir it slowly and you will have no issues with air ...


4

I would use a dual action orbital sander and wet/dry paper @1200 grit a very wet sponge to dampen the area dont press down let the sander float and as the streaks are cut out the residue will turn milky, keep wiping and moving this high grit with water will leave a mirror finish, I have used 800 & 1000 to remove larger imperfections but the 1200 works ...


4

The following is a carry over from a CNC video I saw many moons ago, but have lost the link. Give the selected adhesive a sacrificial material on which to bond. Your thoughts of using plastic bags aren't far off, but let's add in a layer of adhesive that you can remove. If you cover the clamping boards with wide painters tape where the glue is going to ...


4

Bonding anything together without sanding either down to bare wood grain, or at least scuffing the finish surface prior to bonding, will be tenious at best. Having said that, if all you are trying to do is glue them together so one for not move, the bonded material is not weight bearing or subject to vibrations....it might work for a while. Your choice of ...


4

As Harper mentions old poly can be a problem, but poly that is not well mixed (stirred not shaken) can also be an issue. If you sand you may well have scratches but don’t strip again--you need more coats and a very fine sand paper or fine steel wool between coats for best results. I have put more than a dozen coats of poly down for a gorgeous finish. ...


4

From what you've told us, it sounds like you are trying a number of good ideas to help mitigate the smell and lingering off-gassing but maybe not optimally. I actually would advise against using bowls of water or vinegar and adding unnecessary moisture to the air. You actually want to remove moisture from the air (air conditioners //air dehumidifiers do ...


3

Yes (with some prep), however, you can try lightly sanding with 600 grit wet/dry sandpaper. Use it lightly wetted. Buff dry with a soft cloth. You may find this is matte enough.. DONE! If its too matte (flat) you are now prepped and ready to recoat with satin or matte.


3

I really doubt you can sand your floors. Some engineered floors can be but this is a very small percent. And this would be a diy because pros won't want to be responsible for the thin top layer sanding through. One of the things I have found with engineered hardwood is the clear coat varies drastically from different types. I have tested a lot and some ...


3

Glossy or not, a smooth finish feels wonderful and protects better. Especially on something as abused as a table top. If those dust nibs you didn't sand out get knocked or scratched out at some point, it may result in a hole all the way down to the bare wood. Once moisture enters such a hole, well... you obviously have problems. Assuming that convinces ...


3

Interesting question... I'd never think to use scotchgard. It might work, but if it doesnt, any finish you try to apply on top will not stick. Maybe try this in a hidden area to see if it provides protection. Tung oil can be a mixed bag - there's a difference between the pure stuff, the tung oil + driers, and the tung oil "finishes." So if you buy the ...


3

I've used the steel wool + vinegar method before*. It's essentially a stain so really only affects the surface layer. It shouldn't have any meaningful affect on the strength of the piece of wood. Splitting and warping is related to moisture and drying so wouldn't really be affecting by weathering stain. After you weather it, note that most any additional ...


3

Turn up the heat while opening windows across the house. Put in fans in windows/doors blowing in the house on one or two sides. Just don't put fans blowing in all windows so air has an easier chance of escaping. It would be better to open all windows partially than two windows fully. Definitely make sure you have at least one fan though to create a ...


3

Generally, yes - you can help protect the wallpaper with polyurethane. However, once the paper is on, it's not coming off without a complete overhaul (sand it all off and redo it), and you should be aware that paper tends to fade and yellow after a while. Also, if you use a brush to apply water based poly then you need to apply it kind of quickly and be (...


3

Preventing runs is as easy as following one simple approach: Start heavy, finish light. What that means is that you immerse your brush to maybe inch of depth, scrape off one side on the can, and apply the remaining product load to the project in a new area adjacent to the previous work. The idea of "starting heavy" is that you apply enough product to ...


3

Yes, their are things that help with polyurethane fumes, masks with volatile organic vapor cartridges, usually activated charcoal. VOCs are not particles of "stuff" so a particulate filter (N95, P95, Etc) does not help with them. This means a typical size in microns is also irrelevant because you are dealing with molecular size when it comes to vapors. ...


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