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Newsletter #172

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bill.jpgGreeting from Bill Boxer, Sr. Vice President,
             Apollo Sprayers International, Inc

A good part of our readership is involved in woodworking, and for good reason.50new.jpg

It is a market that Apollo has dominated for many years with a wide range of HVLP turbo spray systems from the serious home craftsman to the professional finisher. At the same time, the versatility and range of Apollo HVLP turbo spray systems has found its way into many other markets for diverse applications.

Recent HVLP technological advances by Apollo Sprayers Inc. has ignited curiosity and interest in this specialized spray finishing technology in the automotive marketplace and along with it a host of questions by not only our readership but those interested in spraying many of the specialized automotive paints.

While I can devote pages of text on the subject of spraying automotive paints with Apollo HVLP turbo spray systems, I want to try to answer a few of the basic questions that now seem to be coming up. Beyond that, I want to refer you to Apollo's independent website dedicated to the TURBOPRO HVLP Series of paint spray systems www.turboprohvlp.com for the applications of automotive, marine and aviation paints and encourage those of you with questions to write in or call to learn more about this subject.

The most frequent questions asked is whether or not automotive paints can be sprayed with Apollo's alternative ECO, POWER or PRECISION Series systems. The best answer is a reserved "yes".

As with all coatings, finishes and paints, there is a wide diversity in automotive paints from fairly easy to apply single stage paints (solvent based lacquers or enamels) to complex base coat/clear coat paints systems both solvent and waterbase. There is further diversity between paint manufacturers in formulation making some easier than others to apply.

While there is no rule of thumb, the newer paint technologies generally require the highest available HVLP turbo spray pressure that can be achieved. In this case we are talking about a 5 stage turbo spray system. It is definitely possible to apply some automotive paints with a lower powered turbo spray system. Experimentation will be the guideline.

Here are a few suggestions should you choose to venture into these specialized paints.

1. Most of the sophisticated paint spray systems offer various reduction solvents to achieve a recommended viscosity. We recommend always using the slowest solvent available, sometimes known as a hot temperature solvent. This aids leveling and flowout by keeping the paint wet slightly longer.

2. Sometimes, reducing the paint an additional 5% - 10% will aid in improving atomization should this be necessary if the maximum available HVLP turbo spray pressure is not enough.

3. A smaller nozzle/needle assembly also aids to enhance atomization. We are suggesting 0.8mm with a specially designed air cap for a boost in pressure.

A bit of trial and error and experimentation will go a long way to achieve a desired result however should you be very serious about applying the specialized products used to spray automobiles, boats or airplanes you may want to consider the specialized HVLP turbo spray systems Apollo has innovated for these markets. The TURBOPRO HVLP Series has enhanced technology that helps boost power/pressure to ultimate levels for the newest and modern paint systems used in these industries.

Should you have friends or associates who work in these industries, let them know that this excellent technology is now available to them and certainly worth a look and try.

Last, let me not forget to remind you to look for our monthly special in honor of Apollo's 50th birthday this year.

This month we feature the PRECISION 5 Spray System.

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• PRECISION: Pressure Control System (PCSTM) controls motor speed, voltage and amperage adjusting automatically for altitude and barometric pressure assuring precise atomizing pressure worldwide.
• POWER: Documented 80% transfer efficiency and 38% savings on coating when compared with compressed air systems.
• NEW: Throttle Back Control (TCB™) – Permits highest available flow pressure and increased motor longevity.
• NEW: LCD Message Center – Accurate Pressure Display – Motor Idle – Temperature – Hour Use Meter
• Apollo Sprayers Model PRECISION-5 comes equipped with the Award Winning Atomizer 7500 and our Handi-Hold® Spray Gun Docking Station, an Apollo innovation. Store, hold or transport your spray gun in a vertical position with no risk of knocking or falling over. It’s ready to spray when you are.

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                            From the Apollo Sprayers Birthday Archives

In the 80's, before the advent of new heavier coatings,
the Apollo 500 was our best seller.
single stage, 2 PSI, 40 CFM

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Proper Preparation for a Better Finish
carl1.jpgBy Carl Duguay

One of the not-so infrequent complaints I hear from woodworkers new to the craft is their dissatisfaction with the finish they've applied. When we review what they are doing, we often find that the problem has as much to do with how the project was prepared as with the type of finish used, or the method used to apply the finish. Everything starts with a good foundation, and with finishing, it's proper surface preparation.

Woodworkers typically use one or more of these methods to prepare a surface for finishing:

• machining the surface with planer and jointer,
• sanding the surface with power sanders or by hand,
• scraping the surface with card scraper, cabinet scraper, or scraping plane, and
• hand planing the surface with planes or spokeshaves.

Use Machines to Dimension Your Stock

It's easy to think that surfaces prepared on jointers and planers are ready for finishing – particularly when working with wood that has a straight grain and a fine, even texture. Surfaces may look and feel quite smooth, but closer inspection almost always reveals the presence of minute grooves, or ripple marks, on the wood's surface. While the marks may be very small indeed, they need to be removed in order to ensure a first-class finish. And, don't think that machines equipped with segmented (aka helical or spiral) cutterheads do any better – they also produce ripple marks that you will want to remove. The principle here is that machinery (including routers and shapers) are used to dimension your stock, not to prepare surfaces for finishing.

That leaves sanding, scraping, and hand planing. All three methods are capable of producing superb results - the key is that whichever method you choose, learn to use it effectively. In the long term though, it's worth investing time to develop proficiency with all three methods, as the type and characteristics of wood, and the effect you're looking to produce, will often dictate the method of surface preparation to use. For example, when you machine surfaces that are highly figured (bird's eye, fiddleback, curly, spalted, and the like) you'll inevitably end up with some tear-out. Using a scraper or hand plane is the most effective way of dealing with torn grain. You'll find that when you sand the edges of boards there is a tendency to round over these edges. To maintain square, crisp edges, you'll want to use a hand plane instead.

Patience and a Critical Eye

Regardless of which method you use to prepare a wood surface, the overall goal is to make the surface smooth and blemish free, so that it will accept the finish evenly. This is important because the finish will not only bring out the natural grain and beauty of the wood, but also magnify any surface defects. In particular, torn grain, surface dents, an inconsistent scratch pattern from sanding, or errant bits of dried glue – which may be barely visible prior to finishing – will be glaringly apparent after the finish is applied.

It's a good habit to assess your progress at regular intervals. Use a pencil to draw faint lines across the work surface, and sand, scrape, or plane until the lines disappear. When sanding you can repeat this for each grit you use. It's also helpful to shine a light across the work surface at about a 30° angle – this will serve to highlight imperfections that need attention.

As for much of woodworking, patience is a prime key to success. It's not good enough to know what to do, you need to consistently implement the right techniques. Slow and steady really does win the race when it comes to surface preparation.

Start with Sanding

proper-preparation-for-a-better-finish.jpgI always recommend that people new to the craft begin with sanding, which is easier to master than scraping or planing.

There are quite a few abrasive brands on the market. The two that I particularly like are Norton’s 3X Aluminum Oxide and Mirka Gold, both available in sheets and discs. These stearated abrasives are flexible, don't wear out too quickly, and don't overload (clog-up) with dust too much.

For power sanding choose a variable speed random orbital sander (R0S), like the Bosch 3727DVS, which comes with a dust bag and can also be connected to a shop vac. ROSs have an offset drive bearing that causes the sanding pad to move in an elliptical orbit, which reduces scratching against the grain. You can move the sander in any direction across the wood surface – with the grain, diagonal to the grain, and even against the grain.

For surfaces straight off the jointer or planer, you can likely start with 100-grit discs, or even 120-grit if your machine cutters are particularly sharp. You only need to sand until the mill marks, or any other imperfections, are removed. Then wipe the surface with a rag, and move on to the next higher grit. Use the pencil line technique mentioned above in between each grit. The grit sequence I typically use is 100 (or 120), 150, and 180. However, on highly figured wood I may sand up to 400 or 500-grit. The characteristics of the wood and the type of finish you plan to use will influence the grit sequence. Experience will be your best teacher.

To end things off, hand sand the surface with a sanding block – which you can make from a piece of flat hardwood –in the direction of the grain. Use a grit higher than the one you last used when power sanding – for example, if you finished power sanding with 180-grit, then use 220-grit sandpaper.

Then Move Up to a Scraper

Once you've mastered sanding, give scraping a try. You'll find that scrapers remove material much faster than sandpaper, and they create shavings instead of sawdust, which makes less of a mess. I suggest you start with a cabinet scraper (such as the Veritas Cabinet Scraper from Lee Valley), which is easier to use than a card scraper, and much less expensive than a scraping plane. The key to using them effectively is – you guessed it – practice.

When sandpaper dulls you just grab a new sheet. With a scraper you'll need to refine the edge of the scrapers' blade – first by honing the edges of the blade square, and then putting a burr on the cutting edge. It's not a difficult process to learn, but it's critically important. I find that most of the problems woodworkers have when scraping has to do with dull or improperly maintained blades.

Don't Rush Into Hand Planing

Hand planing is to woodworking what an electric guitar is to rock and roll. There is a lot of panache and charisma associated with them – if not from fellow woodworkers, then certainly from the general public. However, while hand planing can produce a surface that's glassy smooth, ready to accept a finish, it does require a much higher level of skill and experience.

I think it more prudent to resort to hand planing only after you're comfortable using planes for basic stock preparation and general jointing and edging tasks. More so than for scrapers, you need to learn how to properly sharpen, hone, and camber a plane blade for it to be effective at smoothing operations. And, you should expect to invest quite a bit more for one or two good quality hand planes, along with a couple of benchstones, and a powered grinder, than for a sanding kit.

So, there you have it. Whatever method of surface preparation you choose, use a consistent and diligent approach. Learn the fundaments of sanding and you'll produce finished surfaces that beg to be touched. Then move on to scraping and hand planing so that you can tame even the most ornery surfaces.

 

Q&A from Our Finishers

Our reader asked how to fill the grain on a table that had been finished previously finished.


The question is answered by Darren J. O’Hare, Professor at Palomar College.

Darren includes a video.

You finished a library table a few years ago with a stain and a wipe-on poly. Now you are wishing to go back and fill the grain of this piece. Without seeing the piece, I am guessing it is an oak table. I am also going under the assumption you followed the directions of the wipe-on ploy, which means you would have applied about 3-4 coats of wipe-on poly.

Fortunately for you this is not a difficult task.

There are a few options you can go about doing this. This will take a little bit of elbow grease to get this done.

The 1st option is to grain fill the table using your wipe-on poly.
You can sand back your wipe-on poly to just before you hit the stain. If you notice the stain in your sanding dust, then you have sanded down too far. Go ahead and reapply about 3 coats of wipe-on poly, then again sand back down. You will need to do this about 8 times (if this is an oak table) to fill the grain to the surface of the wood.

The 2nd option is a bit easier.
This will require you to sand down the entire table top to the bare wood. Once you have sanded the table back to the original wood, reapply the stain. I recommend an oil based stain. Allow the stain to dry 24 hours. Once the stain is dry you can start the grain filling process. I would recommend a water-based grain filler. This will allow you to get multiple coats on in a brief time period. An oil based grain filler will require roughly 8 hours between each coat. Your table top will require a minimum of 8 coats grain filler (again provided it is an oak table).

Here is a video for the application process of grain filling.

Here is a link to Aqua Coat, a water based, non shrinking grain filler.

 

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.

 

PROPER PREPARATION

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