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14

Read the instructions on the can. See what the manufacturer recommends. Sandpaper is fairly useless on polyurethane because the heat generated by the friction causes the polyurethane to melt and block up the grit. And the finer the grit, the faster it gets blocked up. I have been using polyurethane for more than 30 years. Here is my routine to achieve a ...


14

I use 220 grit. You sand polyurethane to (a) remove any dust bumps in the lower coat, and (b) cut the surface of the lower coat so that the upper coat has more surface area to bond to. You don't need the lower coat to be super-smooth because the upper coat will cover the roughness from sanding anyway. For application, I use a china bristle brush. I've ...


12

The sanding of coats in-between is to give the new coat something to adhere to. It roughs up the surface just enough to give it a bit of grip. Multiple coats is the same as anything else. Multiple coats makes the coating thicker, stronger and more lustrous. Cars have multiple coats of paint to protect the body; you paint your walls with multiple coats to ...


11

According to FDA regulations, the typical clear wood finishes that dry to a hard film, including polyurethane, are considered food safe. Wait to use the surface until the finish is completely dried, and clean it before allowing food contact. Polyurethane is a fine choice to use on a counter, as long as you don't use the counter as a cutting board. If you ...


10

Surface finishes are notoriously difficult to get smooth when the process is interrupted. The glossier the finish, the harder to have sections blend. If you are talking about preliminary coats, especially if they will get a light sanding between coats, this is probably ok. For the finish coat, I would strive hard to do it all in one shot. If you simply ...


10

When you apply multiple coats of urethane, any dust or small flaws will be amplified with each new coat. If you want the smoothest finish possible, then wait until it is dry, very lightly sand with very fine paper (220 or finer) to remove any dust bumps, wipe it clean with a slightly damp cloth or tact rag, let it dry or buff it dry with a dry cloth, then ...


7

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 ...


6

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 ...


5

I generally spray-finish when I want to have a true satin sheen. I find that it's much easier to manage the application when I'm trying for a Satin finish, even if I'm just using a rattlecan, especially for the final coat. I might just suck with a brush, but I tend to find that I leave either brush strokes, tiny bubbles, or areas of uneven thickness that ...


5

Can exposure to heat in the can or while drying affect the sheen of polyurethane? No. Is there anything I can do to compensate? Yes... As a hardwood flooring installer for 4 years, I often recommended against any kind of gloss finish (It looks great at first, then it looks horrible for awhile, then it looks okay - but isn't glossy anymore). I often ...


5

There's no need to stain if you like the color as it it. Staining won't do anything for you and will just take more time. Chances are that your boards might already be pretty smooth, so I'd start with fine sandpaper (200 and above), not rough like 60 grain, except on edges that have been cut. If you use 60 grain on a surface which is already smooth you'll ...


5

I would keep them the same if it's not too inconvenient. Different manufacturers (and even different batches from the same manufacturer) may have different drying properties (the Satin may come out differently). They may also have trouble adhering to one another which would lead to cracking between layers and may also yellow differently, producing a ...


5

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 ...


4

What you're looking for is Spar Urethane. Polyurethane is not good for outdoor use. Spar urethane will hold up the UV rays better.


4

The gloss in clear finishes is reduced by flatting agents which are suspended in the clear finish. Flatting agents are tiny particles that reflect some of the light back, thereby reducing the sheen of the finish. If they settle out or are not mixed well, then the finish will be more glossy, so it's possible you did not mix the finish as well the second ...


4

Spray foam insulation for large areas with a closed-cell foam tends to be a job performed by professionals. They will mask off the area being sprayed, and bring in a bunch of specialized equipment to do the job fast. The result doesn't require a separate vapor barrier since closed cell foam is a barrier. It does have the downside that any future repairs or ...


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

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 ...


3

Even with a clear varnish pine will go yellow/orange with age, so adding a colour will make it darken even more quickly. A couple of coats of clear varnish will seal the wood and stop it darkening too quickly, but you may find you have to refinish the shelves in a few years to return them to their current colour. As DA01 notes in his comment, pine is ...


3

When I use oil based products I use disposable pan liners so cleanup means let it dry-up and throw it away. To clean brushes I use a brush spinner to remove as much material as possible. I swish the brush in a container of mineral spirits and brush a piece of dry cardboard to get out some more of the urethane. Finally I soak the brush for a couple of days in ...


3

There's a chance you were using wiping varnish or a "tung oil finish" (not really tung oil). It's basically thinned down poly that can be left on in a thick coat, or the excess can be wiped off after a coat is applied. The warning to not let the finish dry without wiping is probably good advice to eliminate the possibility of runs and drips. Popular ...


3

When I did my floors I wrapped the lambswool with kitchen plastic wrap, the kind you would wrap a sandwich with. That kept it moist for at least a day. If I went several days between applications, I would just use a new lambswool. It's not good to use mineral spirits (or many other cleaners) bare handed. The health risks just are not worth it. If you don't ...


3

There are a number of low VOC finishes on the market.Two are Safecoat Polyureseal BP and Minwax Polycrylic. They have one problem. If you have a dark finish, they tend to collect in corners and appear white against the dark stain when they dry.


3

What you will want to do is to get a polyurethane stripper with brush, a pair of rubber gloves, a scraping tool, fine grit sandpaper (200), a clean cloth, and a well ventilated room. Start by applying the polyurethane stripper liberally and evenly over the wood using the brush. Let it stand for about 5 minutes or whatever the directions instruct you to do. ...


3

In most cases, if you have done all the right things like sanding and cleaning between coats, you should be done and have an excellent smooth glossy finish. Any further sanding or polishing with any kind of abrasive will dull the finish. Normally urethane does not need a wax. After some use and a good week or two of total cure time, a regular furniture wax ...


3

It's possible it's just the cool temperature and it will dry in a few days. It won't hurt to let it sit several more days and see if the tacky areas harden up on their own. However my suspicion would be a compatibility problem between the urethane finish and the "green" mineral spirits. Although they probably say then can be substituted for real mineral ...


3

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.


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

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 ...


3

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 ...



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