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Newsletter #183

         

Greetings from Bill Boxer
Great news from Apollo Sprayers:

Apollo Sprayers just announced that the PRECISION-5 turbo paint spray system now has an unprecedented 5-year limited warranty.

This is another Apollo Sprayers first – a – 5-year limited warranty on all PRECISION-5 models.  Apollo is  all about innovation and leading the market with design and quality.  So it certainly follows that there is no better way than to stand behind innovative cutting edge technology than with the industries best warranty. 

The PRECISION-5 is designed with patented features that increase the efficiency and motor longevity, so providing our customers with the peace of mind to back that up seems like the right thing to do.

Do you know about the Japanese technique Yaki Sugi? Our featured writer Greg Williams has an excellent article describing the uses and explaining the technique.

April Special of the Month:
$50 off on the PRECISION-5,
plus a free 1.3 needle and tip.

 CLICK HERE FOR MORE INFO ON THE PRECISION-5.

YAKI SUGI REDISCOVERED   By Greg Williams    

A few weeks ago I had never heard of Yaki Sugi or Shou Shugi Ban; now I’m seeing it all over the place.  In Japanese, Yaki Sugi means roughly “burnt Cedar’ and has been used to one degree or another since the 1700’s for making exterior wood structures such as fences, decks, cladding and shingles for houses and other buildings.

Where I’m seeing it now, both in actual use and in advertisements, You Tube demonstrations, flooring and furniture show rooms, and TV shows, it is being used for new and refinished furniture, decorative accessories, art works, wall panels and just about anything you can make out of wood.

The basic idea is to alter the look, particularly the color, and the texture, of either the wood of which an object or construction is to be produced, or the item itself, after its construction.

Probably the first use was serendipitous; a partially burned piece of wood was deemed decorative, useful, or both, and was placed into service.  An example could be a stick one end of which had been charred, and it was discovered that scraping off the char left a more pointed and less frayed end, which was also harder than the original wood. The uncharred but “baked” portion of the wood under the char is found to be harder, and to hold a point better than the unheated wood.  Now we have a spear.

Somewhere, certainly many times, it was discovered that the charred wood was less likely to be damaged by insects, birds, rodents and mold, mildew and other forms of rot.  Probably the char was less appetizing, and certainly less nutritious to plant or animal life. While termites will eat charred wood when nothing better is available, they are less healthy and vigorous than those feeding on the more nutritious uncharred wood.

It is commonly claimed that yakisugi is more fire resistant than untreated wood.  Since fire resistance is difficult to quantify, and has variable meanings, there is some controversy about this claim. The charred wood used in a cladding manner, such as flooring and siding on a structure is more difficult to ignite than untreated wood used in the same manner.

The wood is composed primarily of cellulose, lignin, and water.  Cellulose is the softer, less dense, more volatile and earlier produced compound.  Lignin is harder, denser, less volatile, and is produced later in the growth of the wood.

When wood burns it goes through stages.  1. Evaporation, or the driving out of the moisture in the wood. 2. Pyrolysis, the initial burning of the cellular structure between about 500⁰F and 1100⁰F, when volatile gasses and liquids are being consumed and creating heat 3. Charcoal burning, at above 1100⁰.  Heat is being released more slowly and evenly than in the previous as the charcoal is consumed.

When the wood has been charred to form yakisugi, and subsequently exposed to heat in the presence of oxygen, the temperature needs to reach about 1100⁰ for ignition to take place.  Since the more easily ignitable cellulose and lignin are no longer available as fuel at the surface, and are thermally shielded by the charcoal layer, the yakisugi is more difficult to ignite, requiring a greater temperature and/ or a greater time of exposure to the heat.

The photos depict four degrees of charring on 5/4 pine decking boards.  These are not necessarily distinct stages, but merely stopping points along a continuum to illustrate the effect of the heat. The actual effects will vary according to the wood species, cut, moisture content, thickness and myriad other factors.  

The light char on the first board has affected color significantly, emphasizing the contrast between the early wood and late wood, taking the pale, almost white wood to a toasty warm rich brown, with little effect on the texture.

The second board is heated a bit more and darkened significantly.  Sap has exuded from the knot, and cellulose has been consumed, altering the texture subtly, but the surface is fairly clean without the loose crumbly char to be seen in subsequent samples.

On the third board, there is little of the light wood showing, and some splitting has begun.  It is likely that color will transfer from this board to whatever rubs against it.  Brushing this board with a stiff brush will help prevent that as well as giving a bit higher sheen.  Often yakisugi at this point will be clear coated with varnish or a penetrating oil finish, but as those coatings are in themselves flammable, they will decrease the fire resistance.

We’ll call the 4th board “Full Char” as more heat will significantly reduce the strength of the board without changing the look very much until pieces start falling off.  At this point I would be very careful about the stresses this wood should be subjected to and would not use it as a structural member. This char is almost pure carbon, and can transfer color easily to whatever rubs against it, so it is generally coated with a film forming finish.

Other coloring techniques can easily be used along with the charring.  For instance, a coat of lacquer sealer over the full char followed by a white or light grey glaze, wiped clean and topcoated can create a dramatic textural accent.  On the first board, light char, a dye stain applied after the char can provide hundreds of variations on the original theme.

A traditional way of producing this char on decking, fencing, and cladding and generally on any boards rather than assembled objects or structures was to temporarily bind together 3 boards, edge to edge, perhaps with wire or nails to form a triangular tube.  

Prepare a base over which the tube can be stood vertically, and in which a small fire can be built.  The tube will serve as a chimney.  Use supporting stays or poles to hold the tube securely, but which can quickly be removed.

Start a small fire under the open bottom end of the tube and allow the flames to propagate up the chimney until the desired level of char has been reached.  With longer boards, it’s a good idea to flip the tube end for end in the middle of the burn to get more even charring over the length of the boards.

When the inside of the tube reaches the desired degree of char, the wood tube should be dropped onto the ground, the containment wires removed and the boards flipped charred side up.  If the flames do not extinguish quickly, douse them with water and allow the boards to cool.

For smaller objects, a propane torch or brush burner, or even a high heat electric heat gun can be used effectively.

I expect we’ll be seeing more of this and similar techniques in the near future.

Q&A from theFinishingStore.com

Q: I’m new to woodworking. I have messed up two projects with bad finishing. Now I hesitate to finish.

A: Don’t be afraid. The only thing you can do in finishing that can’t be fixed fairly easily is to blotch the wood with a stain or decide after you have applied a stain that you don’t want it. All other problems can be fixed, with the worst case being that you have to strip off the finish and begin again. Nothing is ruined.

Blotching which occurs on softwoods such as pine, and tight-grained hardwoods such as cherry, birch and maple. It’s difficult-to-impossible to totally avoid blotching on these woods if you use a stain.

So, depending on the wood you use, it’s really the stain you have to be concerned about, not the finish. You can’t “ruin” anything with a finish. Choose your wood and whether or not to stain with this in mind. 

Q: Can I ever strip with alcohol rather than paint stripper?

A: Almost all furniture and woodwork finished between the 1820s and 1920s was finished with shellac. But if you want to test to be sure, here’s the way to do it.



Put a little denatured alcohol on your finger and dab it onto an inconspicuous area of the finish, as shown in the accompanying picture. If the surface gets sticky or if the finish comes off on your finger, the finish is shellac.

Shellac dissolves in alcohol, so you could use the alcohol to strip the finish if that is your intention, instead of using paint stripper.

Q Do you really need to clean your spray gun every single time you use it?

Do you need to clean it when you go to lunch?

What if you are putting it away for a week?

Which coatings mean clean “right away?

A: Always clean your gun immediately if you are spraying a quick set up coating such as a two part urethane or epoxy paint. Clean it even if you are going to lunch.

If you are using a pigmented coating and are finished with that color, clean the spray gun.

If you are going from a water based coating to a solvent based, or the other way around, clean the spray gun.

Other coatings can wait until you are finished for the day. Some finishers keep 2 or more spray guns and dedicate each one to a particular coating, such as water based or solvent, pigmented or clear, 2 part or simple.

 Bill Boxer: This week I am going to go over all my spray guns.

Here’s how I prepare my spray guns on a regular basis:

  • First, I test the spray guns for pattern accuracy to make sure the spray pattern is even from top to bottom.  
  • If it is heavier on one side or another, I rotate the air cap. If the problem moves to the opposite side, the first thing I do is thoroughly clean the air cap with spray gun cleaner and my cleaning kit brushes. Generally, the problem is solved.
  • If the problem persists, I look at the nozzle and needle assembly. Again, I clean with my spray gun cleaner and brushes.  If that's not the solution, it’s time to replace the nozzle and needle.
  • Next, I lubricate all the threads with Spray Gun Lubricant.
  • I check the gaskets and replace if necessary. Then my spray gun is good to go.
  • At this time I also make sure I have a supply of cup gaskets, and non-return valves.

Nothing is as frustrating as being shut down for such some simple problems.

Take a Break and Have Some Fun!

See how many words you can find. Look for words horizontally and vertically. You can print this page, including the puzzle, work offline and then highlight words as you find them.

We're So Confident