Your choice of finishes will largly depend on how you intend to use the piece you're building. If the piece will see little hard use i.e it's mostly decorative, like clocks, frames etc. then Watco will do fine. Just keep in mind that it will give you a relatively weak finish as compared to shellac, varnish or lacquer.
(BTW as far as Watco toxicity goes, it's no more toxic than boiled linseed oil and varnish. In fact it IS boiled linseed oil and varnish!)
If the piece is going to see more rugged use and is going to be cleaned frequently (e.g. a table), I'd recomend a wipe on varnish. Varnish stands up to moisture and cleaners better than Watco will.
You might also consider shellac. It's a great finish especially if you plan to rub out to a high gloss. You should allow yourself some time to practice a little. Due to it's fast drying time, it can be trickier to apply than varnish.
As for sanding - you really don't HAVE to start with really coarse stuff all the time. The real deciding factors are:
Is any surface kinda rough already?
Do any mating pieces need to be flushed up?
Experience will make answering those questions more accurate. When starting out, it's not always clear how to decide those things. As a beginner, I underestimated what each grit could do. I used to start out with 220 and try to flush up a butt joint. Then i'd go the other way and use 80 on something fresh out of the planer. It's tricky at first to know where to start so it's probably good to lowball it at first. But eventually you'll get a better handle on where to start.
My general rules are if I need to do any flushing, i'll start with 100 or 120. If any surface is pretty uneven (scratches, dings, etc) in which I will need to remove some material to get by, i'd also start around 120 or 150. If all my surfaces are pretty smooth already with no major (subjective) dings and all my joinery is flush, I may start at 180 or 220. I may not sand at all in some cases.
Knowing when to stop is also subjective. Some would argue that if you aren't going to stain the piece, anything over 220 is pretty much a waste. If staning, some say to go as far as 600. Others caution against going too high or you end up burnishing and the stain will have few places to soak in. For me, I rarely ever stain and always use a conditioner if I do. I generally go to 320 on most of my projects. Some things I'll go up to 600 - depending on my mood that day, really. I don't have a better explanation for when/why i go higher. On a piece that may get handled alot, I tend to go higher, just because I think it contributes to the overall feel of the thing.
I don't know much about many finishes, unfortunately. I have had good luck with polyurethane and tend to stick with it. I'll usually thin it 50/50 with mineral spirits and wipe it on. I sand with 400 or 600 between coats and the last coat gets a light rub with 1200 grit just to soften the nibs a bit.
As previously mentioned, what final finish to apply is fairly subjective. I base that decision primarly on what the intended use of the piece is...
What grits to progress through for sanding depends on wood species and whether you're "hand" sanding or using a corded sander(s). In general, though, starting with 100 grit and progressing through 180 grit is all that's needed when using an obrbital or random orbital sander. On really close grained woods such as maple, 220 is as high as one needs to go, any higher and you are wasting time...
The main things are to remove any milling marks and to work through the grits without "skipping". When sanding by hand you should use a sanding block faced with cork...Below is a "primer" on sanding that I posted here a few years back:
Not too long ago I had an e-mail exchange with a friend of mine who is very much involved in woodworking shows, demonstrations, and woodworking guilds. The crux of the “conversation” being how there is seemingly a vast number of woodworkers that have very little understanding of even the most fundamental and basic aspects of working with wood. I too have observed this phenomenon in the small number of “demos” that I’ve given locally, out in the field, and what I’ve observed on various forums. This includes the most basic task of all; sanding.
Out of all the tasks we perform sanding is probably the most boring and mundane of them all. Yet, it is the most crucial operation to the success of ones’ project, both in terms of preparing the surface for finishing and finishing itself. I am often times amazed how very few actually have “mastered” this most basic of woodworking operations. The very first thing I was taught to do when I was a little shaver was how to sand.
While I personally try to avoid abrading wood at all costs, sanding is necessary at times and must be done when applying film finishes. This “primer” is not intended to be an indictment against sanding but to help others achieve better results in their woodworking efforts. While it does not require a high degree of skill, it does require a skill nonetheless. Most folks appear to believe that sanding is something that arose out of the early 20th century with the invention of sandpaper. This is not the case; in the 18th and 19th centuries’ sharkskin, pumice, and other abrasives were used. So, yes, sanding has its “traditional” applications.
For those of us who work with wood there are three basic types of sanding papers; aluminum oxide, garnet, and silicon carbide (wet/dry). There are also various cloths such as emery cloth and resin bonded aluminum oxide that are used on belt sanders, drum sanders, and etc. I will try to keep this limited to the 3 basic types of sanding paper. Personally, I prefer aluminum oxide sanding paper for general sanding work. I’ve found that it won’t clog as fast and lasts longer than garnet paper. Some finishers that I know prefer to use the very fine garnets for dry sanding between coats. For this discussion, I will attempt to “answer” all the basic questions about sanding but were afraid to ask. ;)
Sandpaper comes in grits; the numeric designation of the mesh openings per square inch. Coarse is 36, 40, 50; medium 60, 80, 100; fine from 120, 150, 180; very fine 220, 240, 280, 320, 260, 400, 500, 600; with the silicon carbides going up as high as 1500. Very coarse and coarse grits are seldom, if ever, used and the very fine grits generally are used between film finish coats.
Like most operations when working with wood, you will always want to sand with the grain to remove milling marks and level the surfaces in preparation for the finishing operations. In a sense, different species of woods have different “grits” too. For example, Red Oak has a much more open grain (coarse) than any of the Maples (very fine). I mention this because, from my observations, most folks fail to match sandpaper grits to the grain of the wood being sanded. In my opinion, this is one of the biggest reasons why most are dissatisfied with their results not only with the actual finished project but also in the amount of time devoted to the sanding operation. Using the wrong grits can significantly increase the time spent.
As a general rule, rough sanding should begin with 80 or 100 grit and ending in the upper spectrum of the fine grit (180) to the lower spectrum of the very fine grits (220 to 320) depending on wood species. Grit progression should always be in order, sometimes (again depending on wood type) the process can be quickened by skipping no more than two grits.
Tools & Technique
The most important and basic tool for sanding is the sanding block. This is the most overlooked tool in one’s wood working arsenal, in my opinion. How many of us will just grab a small block of hard wood, wrap the sandpaper around it, and begin to sand or use one of those plastic sanding “blocks”? A “proper” sanding block should have a cork bottom around ¼” in thickness. The cork is firm enough to help level the service but at the same time provides a certain amount of cushion to allow the abrasive to efficiently “cut” the fibers without quickly dulling the abrasive particles. A selection of good sanding blocks will allow one to quickly progress through the process, be it general sanding work or finesse sanding and it should fit comfortably in the hand.
Here I will digress for just a moment. The friend I mentioned in the beginning recently sent me a selection of sanding blocks to try out. I’ve been doing this for a little over 4 decades and it takes quite a bit to get me excited about tools and I never thought I’d see the day when I could get excited about sanding! When they first arrived I could immediately see that these blocks were worth checking out. They are “dual surface” blocks with ¼” cork on one face and ¼” felt on the reverse face, the felt side being used for initial smoothing and the cork for final sanding. The blocks are made of micro laminated hardwood in the shape of a parallelogram with a side “cove” for a comfortable fit. He sent me all five sizes, ranging from the 4 ½” x 5 ½” block down to the 1” square “strip”. I’ve been “testing” these things for about 3 weeks now and I can honestly say that they are the best sanding blocks I’ve ever used. The bevel cut ends ensure that you can get into tight areas and places where perpendicular grains are joined. They are also the most comfortable blocks I’ve seen and I’ve actually have enjoyed the sanding process with their use. The are called Master Blocks™, at this time I do not have a price list or where they can be ordered from but when I do receive that information I will post it here. I highly recommend them and can assure you that you will be astounded by the results of what a quality sanding block will yield. They are particularly outstanding for finish work.
Beyond the sanding block, there are the corded sanders. Here again, I’ve found that many are “confused” about types and their use. There are belt sanders, disc sanders, drum sanders, straight line sanders, orbital sanders, random orbital sanders, detail sanders, etc, etc; each designed for different tasks. In my opinion, there is not one single sander that can perform all the sanding tasks. I classify them into three basic categories; rough, shaping, and finishing. I include the belt, disc, and straight line sanders in the “rough” category, the drum and spindles in the “shaping”, and the orbitals and detail in the “finishing”. Naturally, there is flexibility in their use with the possible exception of the orbitals and detail sanders, these should only be used as finish sanders. I will note that in the “finishing” context, I am referring to final sanding prior to the actual application of the finish itself.
Regardless of the tool being used, the most common mistakes I see in actual “technique” are applying too much downward pressure, not keeping the paper “clean”, not changing the paper often enough, improper grit usage, and not keeping the sanding surface free from the dust. Some of these may seem very minor but collectively they do “add up.” Probably the most “misused” tool would be the orbital and random orbital sander. Not only do I see a large number of folks using them for initial sanding in the coarser grits but also they are also under the mistaken impression that grain direction is immaterial. This is just not so; sanding should always be performed with the grain. You can “overlap” slightly were the grains are at right angles but one should always finish up the stroke with the grain. For example you are finish sanding a frame and panel cabinet door, the correct method is to sand the rails slightly into the stiles then finish the strokes on the stiles to the joint running the sander’s edge along the line. I’ve also seen many “complaints” about swirl marks being left behind. These result from either too coarse or skipping grits and from moving the sander too quickly across the surface, which appears to be the most common error.
Let the sandpaper do the work for you; hand sanding requires very little downward pressure and when using a corded sander it’s weight alone is enough. Keeping the paper unclogged and the surface free from dust are critical to efficient and satisfying results. If you find yourself having to apply downward pressure, the paper needs to be unclogged or changed. Initial sanding is really a “no brainer”; you start with 80 or 100 grit to remove all mill marks and imperfections in the surface. It’s the subsequent progression through the grits that causes the most problems. Keep the surface free from dust and be observant when you are sanding with the next grit. The object is to remove all marks left by the previous grit, if you’ve missed a spot it will be very obvious when you wipe the dust off the surface with your hand; it will “fill” those imperfections. This is one reason why I use my bare hand to wipe the dust and not a brush or vacuum. When I’m satisfied, then I will vacuum the dust and proceed to the next grit. When to stop sounds like another no brainer but it really isn’t. Most folks actually over sand. As I stated above, wood does have “grit” too. Sanding down to 220 on Red Oak is a total waste of time. Using a random orbital one only need to go down to 150 grit; 180 when using a sanding block. While some recommend wiping down the piece with a damp cloth to check for any sanding marks left prior to applying the finish, I’m opposed to that idea. Even a damp cloth with mineral spirits can raise the grain (which you’ve just spent all this time trying to level) and can leave an incompatible residue with the final finish. Use your hand to wipe the sanding dust off the board, then used the compressed air and vacuum if it meets your approval. The sanding operation will go much quicker and will become a much more enjoyable process when done correctly.
When sanding between film finish coats, I prefer silicon carbide paper to any other product other than pumice and rottenstone. Steel wool is never used in my shop for finishing. Its major drawback, as I see it, is the residue left behind. The steel fibers can get imbedded in the piece, especially on the more opened grained woods. In a lot of cases even a very thorough vacuuming and use of compressed air can not dislodge these fibers, on an exterior piece you run the risk of these fibers rusting which can really bum you out.
That being said, my choice of grit and whether I use it wet or dry depends largely on the actual finish I’m sanding. Generally speaking, I use 200 grit, dry, between coats, then use 320 or 400 grit, dry, on the second to last coat, always by hand and with a sanding block. This is often referred to a “scuff sanding” to lightly abrade the film finish for a good bond for the next coat and to level any imperfections on the previous coat, a very light touch is the norm. If I’m “rubbing out” using silicon carbide, I lube it with water, going down to 600 grit for a satin sheen, 1200 for semi-gloss. I will always use compressed air, the shop vac, and a damp cloth to remove the residue. Here I am very diligent and have been known to use a magnifying glass for inspection, particularly when preparing for the final coat.
In closing, sanding is an acquired skill, though not one that I would call “refined” or one that requires a high level, it is a skill as I said from the outset. One that is the very most basic and often times, the first one we learn. It’s my belief that because it is so basic, it’s often the one we take for granted the most. Even if all the other skills one possess are finely honed, this one, if not developed, is generally the most obvious when the project is finished. By experimenting with the different types and grits on different woods species by hand, you can quickly apply those “lessons” to the corded sanders as well. I will also share that sanding is probably the most “intimate” operation in working with wood other than applying a hand rubbed finish; it is here that we tend to caress the piece, feeling for any imperfections. By using your non sanding hand to brush away the dust you will stay in touch with the operation, when sanding completely by hand it is very akin to hand planing; preparing you, perhaps, to acquire that skill. It can be a very satisfying operation, one that can be looked forward to and not dreaded, one that at the very least can offer you time for contemplation, and at most give you great satisfaction and pride in a job well done. Whether one chooses to sand, scrape, plane, or any combination thereof, learning how to sand is the first step.
Just yesterday, we used clamps after glue simply to take the bow out of the wood we were using, and it straightened everything out for us. Usually though, any time you lay up a project the clamps are...