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  1. #1

    Default Shellac tutorials

    What In The World Is Shellac?
    Shellac is a resinous product of secretions from the Lac insect. The resin is collected from trees in southern Asia. In the unrefined state, the product is called seed-lac and comes in many different shades from deep reddish brown to a golden brown color. After the seed-lac is harvested and cleaned of tree and insect debris, it is refined and formed into sheets, which are then broken into chips or flakes that are sold commercially.

    Shellac in one form or another has been in use for possibly many centuries, but has only been used as a popular finish from about 1810 to sometime after WWII when lacquers and quick-drying varnishes started to become more popular. Prior to WWII, shellac was the primary finish for wood cased clocks. It is a durable interior finish that is very versatile in that it has the lowest water-vapor exchange of the finishes. However, it does have certain limitations as exposure to excessive moisture, heat, solvents, acids, and alkali products can damage it. But since clocks are not ordinarily exposed to these conditions, shellac’s performance is excelled only by the beauty it can impart to wood.

    Shellac is safe once the alcohol solvent has evaporated and the finish has cured. In fact, it is so safe that the Food and Drug Administration has approved it as a coating for pills and candy.

    Why Use Shellac?
    Shellac was the original finish applied to nearly all 19th century clocks. It is easy to apply, easy to make, not hazardous to you or the environment, and future generations will appreciate you applying shellac rather than another finish. Shellac exhibits rich warm tones when it is applied to woods popularly used in clock making, such as mahogany, walnut, rosewood, cherry, and oak. Compared to other finishes like varnish (including polyurethane), lacquer, and oils, shellac has the lowest moisture exchange. This is a very important characteristic especially for antiques, because it prevents the wood from expanding and contracting so much when the environment changes.

    Types of Shellac
    There are quite a few types and grades of shellac. In the dry form, shellac comes in flakes, granules, or buttons. The most popular of these is the flake form as it dissolves quickly in the solvent.

    Blonde shellac is a highly processed form of shellac that has the wax and natural dye removed. The use of blonde shellac is applicable when a water clear finish is desired on woods such as maple. However, orange shellac is a better choice for clocks.
    Orange shellac is the most popular color used, and is easy to apply by padding since it doesn’t have as saturated color as some of the deeper shades. The wax-bearing types of shellac contains a trace of wax, which settles out when you mix it yourself. Orange shellac has a natural warm orange tint that is able to impart a beauty to wood, and especially to antique items like clocks. It’s a shame that more people have not discovered the benefits of using shellac, since shellac and wood go together like butter goes with toast. Lately, I have been using dewaxed orange shellac. It produces a more translucent finish. Since it has no wax content, there is no wax that settles to the bottom of the container. This means the shellac doesn’t have to be decanted off like the waxy variety of shellac. Dewaxed shellac flakes should be kept below 80 degrees F to prevent clumping. If it does clump, no matter, it is still useful.

    Other colors of shellac include garnet, button, and dark. In most instances these are too dark as an antique clock finish.

    Seedlac shellac was most commonly used in the 19th century by woodworkers. Seedlac is the least refined and contains bug and tree parts, does not have the dyes refined out, and has a high wax content. Seedlac is a popular among conservators as it closely approximates the old type of finish.

    Storage
    You can buy it pre-mixed from paint stores or hardware stores, but since shellac has a shelf life of 6 months to 2 years, depending on storage conditions, it is best to check the date on the container before buying. Just like buying milk, you’ve got to check the date. The flake form does not have a shelf life until it has been mixed with a solvent. On the other hand, blonde shellac has the shortest shelf life. Dry form blonde shellac has a shelf life, unlike the other types.

    Once mixed with the solvent, the shelf life can be extended by storing the mixture in the refrigerator. Wide-mouth glass canning jars work well since they are air tight containers. The glass container allows you to see when the shellac has fully dissolved, and when any wax has settled to the bottom. Shellac should not be stored in metal containers because the acidity of liquid shellac will cause a reaction with the metal and will darken it.

    To check the freshness of shellac, put a drop or two of the liquid form on a hard non-porous surface like glass. Allow it to dry for an hour. If you can make a dent with your fingernail in it, then discard it and make a fresh mixture. Old shellac will never fully harden.

  2. #2

    Default Shellac tutorials (By: craig)

    OK. Here's the Shellac 201 discussion. I apologize for not posting it sooner.

    For the history of this, please see Shellac 101 Intro posted February 26th, 2005.

    Shellac 201b and subsequent articles will follow.

    I'd like to caveat this discussion by saying that I don't under most circumstances recommend applying new shellac to an old case that has a viable finish on it. That said, it is my desire that poly-whatever, varnish, lacquer and other unappropriate finishes never be applied to any antique clock.
    I only post this discussion so that if you desire to apply the correct finish, what was originally used, to a clock that has been stripped or the finish is destroyed for some reason or another, that you will use shellac.
    * It is easy to apply
    * The finish looks beyond belief as it gives such a warmth and depth to the wood
    * It's the only finish that can impart such beauty (other finishes look dead flat)
    * Shellac is the finish used on nearly all wood-cased clocks
    * Any other finish will devalue your clock to a very large extent.

    How to Make Shellac (Materials: shellac flakes, alcohol, and a wide mouth canning jar)

    Types of alcohol solvent
    Shellac is an evaporative finish that is dissolved in alcohol.
    Shellac is made simply by dissolving dry shellac in the alcohol solvent. The ratio of shellac to alcohol is called a pound cut, which is explained in the next section.

    There are several chemical compositions of alcohol as a solvent, but the most common types are denatured ethanol, methanol, and pure ethanol.

    Isopropyl alcohol, or isopropanol, contains up to 40 per cent water, depending on the type. The water content in isopropanol prevents the shellac flakes from dissolving. In pure form, isopropanol is not suitable for making shellac, since the flakes will not dissolve. However, it can be added in small amounts to pre-dissolved shellac to slow the evaporation rate. Experimentation is recommended.

    Denatured alcohol has a medium drying rate and is the standard alcohol used as a shellac solvent. Consuming denatured can make a person sick. It is a good practice to inquire of the manufacturer of the denatured alcohol as to the water content in the alcohol. Denatured alcohol is a cost effective way to make good quality shellac.

    Methanol, or wood alcohol, has the fastest evaporation rate. It is not recommended because in quantity it can kill a person.

    Pure ethanol or grain alcohol, while cost prohibitive for most wood workers, is preferred by purist conservationists on expensive items, because it contains no water and has no additives. Pure ethanol was used to dissolve shellac in the 19th century.

    So what’s a pound cut?
    A pound cut is one pound of shellac in a gallon of alcohol, and a four pound cut is a pound of shellac in a quart of alcohol.
    Thicker or heavier pound cuts can be challenging to work with because of the problem of lap lines with more concentrated solutions. But typically a 2-pound cut is recommended for most uses. To put this in
    everyday practical terms, one pound of shellac flakes is approximately four cups or 32 ounces by volume. Below is a simple recipe for judging the pound cut of shellac.


    Guide for mixing small amounts of shellac
    1 lb cut - 3 oz. of dry shellac flakes in 12 fluid oz. of alcohol, or 4 oz. (1/2 C) of dry shellac flakes in 16 fluid oz. of alcohol.

    2 lb cut - 6 oz. of dry shellac flakes in 12 fluid oz. of alcohol, or 8 oz. (1 cup) of dry shellac flakes in 16 fluid oz. of alcohol.

    3 lb cut - 9 oz. of dry shellac flakes in 12 fluid oz. of alcohol, or 12 oz. (1-1/2 C) of dry shellac flakes in 16 fluid oz. of alcohol.


    Make your own shellac by adding dry flakes to alcohol
    Adding alcohol solvent to dry shellac is too easy. Once the alcohol has been added to the shellac flakes, mix the solution by shaking or stirring several times so that the shellac will dissolve completely and you won’t have clumps in the bottom. Dewaxed shellac flakes will dissolve in a few hours, while waxy shellacs may take overnight to fully dissolve.

    If waxy shellac is used, then you will notice some off-white wax settling to the bottom after a few days. This is normal as wax bearing shellac contains about 4% wax content. The shellac can be decanted with a turkey baster if desired, leaving the wax in the bottom. But the only reason to do this would be to make the shellac slightly less susceptible to moisture.

    Seedlac differs from regular waxy orange shellac in that it has a higher wax content, but the same wax settling will occur. It is not practical, nor is it recommended, to attempt to decant the seedlac shellac from the wax.

    All types of liquid shellac must be stored in an air tight not-metallic container. Once the shellac is dissolved, it is ready to use.

    How to Apply Shellac

    Remember, good lighting is required for quality finish work. See Lighting Your Workspace for details of lighting recommendations. Shellac should be applied when the relative humidity is less than 90%, and the temperature is within the 65 to 95şF range. Optimum temps are 70 to 80 degrees.

    Another subject to take into account is the final rubbing out of the finish. The kind of clock case the shellac is applied to will determine if any shellac flattening agent will be needed.
    If the case has carving, intricate molding, or other types of deep recesses that would make final polishing of the finish difficult, then the addition of 10 percent to 15 percent flattening agent can be added to the shellac. This product contains fine silica suspended in shellac. Shellac with a flattening agent can be applied by brush or pad to any surface that cannot be easily rubbed out.


    Please see Shellac 201b for the continuation of this discussion.

  3. #3

    Default Shellac tutorials (By: craig)

    How to Apply Shellac Brush Method - (Materials: Quality nylon bristle brush, "Taklon"-type)

    Here are few points to ponder when brushing shellac onto a surface. Shellac is a solvent-based finish. When applied over an existing finish that is just a few mils thick, the wet shellac from the brush contains enough solvent to partially liquefy the existing finish...so don't be alarmed if a finish crinkles a little bit.

    Knowing that the solvent will partially dissolve the previous coat is reason enough to make brisk single-pass brush strokes and not dwell in one place too long, or re-coat too soon. Wait an hour, or better yet, wait overnight before going back over a brushed-on coat to allow the shellac resin to cure. Re-applying shellac over a green finish can disturb the previous coat by making it look rough.

    Although sanding between each coat of shellac is never required nor recommend, be sure to let the previous coat cure for a couple hours or overnight before attempting to sand or use steel wool on the finish. Using a hair dryer to hasten curing will not work very well and you run the risk of creating bubbles in the finish. Remember, shellac is not heat tolerant.

    On a clock case that has had the original finish removed or is in the process of being stripped, (see Philosophical Discussion) and refinished, I like to build up five, or sometimes more, coats with a brush to fill up the pores before padding on subsequent coats.

    A quart of shellac will cover about 100 square feet.

    Foam brushes do not work for applying shellac since alcohol will dissolve the foam.

    Brushing on shellac is preferable for carvings. As previously mentioned, a shellac flattening agent is recommended for surfaces that have carvings or other deep recesses.

    When brushing larger areas, it is advisable to use a thinner mixture of shellac in order to maintain a uniform color. It will take more coats to build a finish. The darker or thicker solutions have more concentrated color that can color-streak, but it’s not as noticeable when brushing with the grain.

    The best brush to use for brushing shellac is one that has flagged tips, fine bristles that don’t release when brushing, and bristles that fill the ferrule. Cheap paint brushes have a void inside the center of the bristle section of the brush. This void holds no shellac.

    A good brush choice is a Taklon nylon brush available from most art supply stores. For applying shellac to antique clocks, the sizes recommended are ľ”, 1” and 1-1/2” wide. It is a good practice to dip the bristles only half way in to the shellac. Brushing in the direction of the grain on larger surfaces gives the best results.

    Cleaning the brush after finishing is not essential, but can be done with alcohol solvent or Tri-Sodium Phosphate (TSP) cleaner available at hardware stores. If you’ve already got alcohol, there’s no point in buying TSP. Since shellac is solvent based, I have not found it necessary to clean out my brushes every time. If the brush didn’t get cleaned the previous use, a pre-soak in alcohol for a couple of minutes will dissolve the shellac in the bristles.

    Shellac 201C soon to follow...

  4. #4

    Default Shellac tutorials (By: craig)

    How to Apply Shellac Padding Method - (Materials: muslin pad, gauze inner pad, squeeze bottle, shellac, latex or nitrile gloves)

    Padding Shellac
    One of the most rewarding experiences for me has been to learn the art of padding on a shellac finish. While it takes some getting used to the technique, it is very easy to do and the results are unbelievable. The shellac goes on in thin layers while padding, but this advantage allows more coats to be applied in short succession.

    To begin with you’ll need a pad, a squeeze bottle, and some shellac. The bottle is a convenient way to apply predictable amounts of shellac to the pad. A reclosable airtight bottle is recommended to keep the shellac from drying out while not in use.

    The pad consists of an outer pad and an inner pad. The inner pad is an absorbent cotton material that will hold the shellac. Gauze-like material works well for this.
    The outer pad should be a low-lint (pre-washed) smooth cotton material like muslin. (An old tee-shirt won’t work because the fibers will come loose as you apply the finish).
    Pull the outer pad tight around the inner pad. There should be no wrinkles or creases on the facing surface of the pad as this will remove shellac rather than put finish down. With the pad fit snugly in your writing hand, take the palm of your other hand and firmly pat the pad to somewhat flatten it out and firm up the wiping surface. A new pad initially requires more shellac than an older one that is saturated with resin.

    To apply the finish by padding, apply some shellac to the pad from a squirt bottle. It will take a couple of tablespoons on a new pad, but as your pad gets moistened it will take less than a teaspoon to charge the pad each time. The pad should have enough shellac in it that it will apply two or three passes with the pad, but not too much that it drips when squeezed. When you’re ready to apply shellac to the clock case, squirt some shellac from the bottle to the pad and wait until the shellac disperses within the pad.

    Using a method like an aircraft practicing touch and go landings, swipe the pad on the surface with just enough pressure to feel it glide across the surface. It should feel like the pad slips across the surface as if it has grease on it. If not, then the pad is too dry and needs more shellac.

    Be careful not to dwell in one place too long with the pad. Don’t scrub the pad on the surface. Overlapping somewhat is necessary, but don’t go back over the same place until the shellac has had a few minutes to set up. If the finish starts to look rough as a result of padding, either the pad is too saturated, or the finish has not had sufficient time to cure. Stop and let the finish dry for 15 to 30 minutes. Better yet, let a coating of shellac cure overnight.

    One of the keys to finishing is patience, as it takes a while not only to learn the “feel” of applying shellac, but also it takes time to build a finish. Once you get good at it, then you can hurry the process along to a degree. You must stop and add shellac once you feel the pad start to drag. This is where the “feel” comes in. If you apply too much pressure while padding, and the pad gets dry, you will be removing finish.
    As a practice I recharge the pad every three to five swipes depending on how saturated the pad is.

    In corners or detail areas it is good to have a fair amount of finish already built up from brushing the finish on. In detail areas, I prefer to leave the brushed on finish as-is. The flattening agent is good for brushing shellac on carved details without any subsequent rubbing out. While working in corners, the pad can be contoured into a point with your finger inside to reach into the area to be finished, but the pad needs to be recharged nearly every swipe for corner work because the pointed area doesn’t hold very much shellac.

    A well-used pad will hold a lot of shellac as more resin builds up in it. That’s the beauty of this process, because a filled up pad will build a finish much faster and can fill pores very quickly. Occasionally the pad will have a blow-out where the outer pad wears through. Just relocate the inner pad to another area and pull the outer pad tight just as in the beginning.

    When finished with that coat, you can store the pad in an airtight container to keep it from drying out. If the pad dries out between uses, just pour a little denatured alcohol on the pad and let the pad soften for a few minutes while you prepare your work. Within a minute or so, the alcohol should have dispersed within the pad, softened the existing shellac, and you can start padding on the finish.

  5. #5

    Default Shellac tutorials (By: craig)

    After the Shellac is Applied

    After several coats of shellac have been applied and allowed to cure at least overnight, the finish is probably ready to be rubbed out. Trying to figure out how many coats of shellac is enough takes a little practice, but when a finish is rubbed out, a good indication of sufficient finish thickness is given by the filling of the pores. Flattening out the finish with 400-grit sandpaper and oil will facilitate in revealing the amount of grain filling that has occurred.

    Leveling the Finish with 400-grit Sandpaper and Oil
    To begin flattening out the shellac finish, start with 400-grit wet/dry sandpaper lubricated with mineral oil or paraffin oil (lamp oil). The oil will not affect the cured finish. The sandpaper will remove any brush strokes, lap lines, and will, in general, greatly smooth out the surface. The desired result of sanding is not a uniform matte finish, but the removal of peaks (lap lines, etc.).

    Regularly wipe the oil from the surface in the area being sanded to check progress. Be careful during the sanding process to not bear down too hard and break through the finish. The point of sanding is to flatten out the finish in preparation for following up with 0000 steel wool. The finish may not be perfectly uniform after sanding, but the 0000 steel wool will take care of that. As always, be very careful when sanding close to an edge, and keep the sandpaper well oiled to prevent corns.

    Important: sand the finish in the direction of the grain whenever possible


    Depending on what aesthetic look you’re trying to achieve, the final sheen should be a good fit for both the age and type of clock being restored. After leveling the shellac finish with 400-grit sandpaper and oil, here’s a summary of steps for attaining a particular finish sheen.

    o Satin Sheen – A toned-down satin sheen can be achieved by rubbing out the finish with 0000 steel wool and wax with no subsequent polishing with pumice or rottenstone. After rubbing with the steel wool, apply a coat of paste wax and buff the surface.

    o Semi-gloss sheen – A semi-gloss sheen can be achieved by rubbing out with 0000 steel wool, followed by polishing the surface with pumice. The case should get an application of paste wax and then get buffed out.

    o Glossy Sheen – Fine clocks may be better suited with a glossy finish that is the result from rubbing out with 0000 steel wool, followed by polishing the surface with rottenstone. An application of paste wax would be the final step.

    As always, whether you stop at 0000 steel wool or polish the case with rottenstone, a final application of paste wax is advised.

    Rubbing out the Finish with 0000 Steel Wool and Wax
    Rubbing out the finish with 0000 steel wool lubed with wax should always be done after sanding to remove any scratches left by the sandpaper. If there are still surface irregularities such as finish accumulations on edges, or excessive lap marks left after the first pass with the steel wool, a little more sanding may be needed.
    The point of using steel wool is to achieve a uniform sheen, while also smoothing out the surface. The uniform sheen helps to spot any leftover finish irregularities. Keep the steel wool pad lubricated with wax to prevent noticeable scratching.

    Important: rub the finish with steel wool in the direction of the grain,

    0000 steel wool and wax will leave a sheen that is somewhere between a matte and a satin sheen. Clean off any residual steel wool, and apply a coat of wax.

    Polishing the Finish with Powdered Stone and Oil
    When polishing the finish using powdered stone (pumice or rottenstone) as detailed in this step, remove any residual steel wool. For a sheen that is between satin and semi-gloss, the next step of rubbing out with ground stone should be done. The grades of ground stone are as follows: 2F pumice is course, 4F pumice is fine, and rottenstone is very fine. Generally, I skip the pumice and use rottenstone, but experimentation with various grades will result in various finish sheens. Polishing with pumice will produce a finish that has less gloss than rottenstone.

    To polish and bring a nice semi-gloss sheen to the finish, I use an old tee-shirt for a rag that is made in a ball-shape similar to a shellac pad. I add mineral oil or paraffin oil to the pad and the surface being rubbed out. The oil helps maximize the use of the ground stone by lubricating the polishing action, while also holding the powder in place. Lightly sprinkle the ground stone onto the surface. A little bit goes a long way. Apply a generous amount of oil to the rag. Sometimes I feel like I’m in the kitchen working with recipes from a cookbook…lightly sprinkle… add a generous amount of oil, etc…

    Rub the surface in a circular motion, replenishing oil and ground stone whenever necessary.

    After rubbing out the finish with pumice or rottenstone, wipe all affected surfaces down with a clean rag before a final wax coat.

    Protect the Finish with Wax
    An application of paste wax with a soft cotton cloth will be the final step for producing a lasting work of art.

    Last step: Enjoy...

  6. #6
    Forums Administrator harold bain's Avatar
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    Default Re: Shellac tutorials (By: craig)

    To make for easier reading, I have put all of Craig's shellac tutorials together into one thread.
    harold bain, Member ch 33
    "If it won't "tick",
    let me "tock" to it"

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