by: Paul H [ ]
IntroductionThis is my third in a series of articles where I hope to provide data for the prospective airbrush purchaser that covers key features, evaluates performance using modeling paints and materials and describes how that performance was measured. I will continue to use standardized products and methods in order to provide situations that can be duplicated by any individual who chooses to do so. From there they can decide what value to place on the information provided.
I have used airbrushes in modeling for about 30 years and I have no affiliation whatsoever with any airbrush, paint or model company. Most of the brushes I evaluate will be brushes that I bought and paid for out of my own pocket. None were received for review or were bought at a discounted rate from a manufacturer for consideration. The ones I don’t personally own, were borrowed from a friend who tolerates my curiosity.
The HOWI will use two readily available modeling paints using thinners manufactured by the companies who produce and sell the paint. This not an attempt to call into question the suitability of various thinners others use and there will undoubtedly be people who can achieve better results with their preferred thinner, but these products provide control factors which provide stable and repeatable methods. The paints used will be Tamiya and Vallejo Model Air. They are readily available via the internet even if they are not in your local hobby shop.
Paints will be applied to sheet styrene using the pressures where best performance for the brush in use is achieved for stated thinning ratios. Lines and spray patterns will be measured using digital calipers so very slight differences will show in metric conversions as they will be taken from the caliper and not from direct conversion of a number. In my opinion, .010” gives a more concrete measurement than .01034” so I won’t go past 3 decimal places. The compressor I use will always have an adjustable and regulated air supply with moisture traps in line between the compressor and the airbrush.
Below are the criteria that I intend to use for all airbrushes I evaluate:
Brand, action type, feed type, trigger type, nozzle type, nozzle size, air fitting size, cup volume, length, diameter and price
Special Features & Accessories:
i.e. MAC valve, solvent proof seals, preset handle, lids, wrenches, water traps, etc.
Atomization, ergonomics, fit, finish, pattern size, smoothness of action, ease of cleaning, parts availability
Tamiya HG-SF Details and Features
Pic 1 The Tamiya HG Superfine (HG-SF) airbrush is intended to be the most detail oriented airbrush in the company’s line. This airbrush has been around for quite some time and has been a proven performer in the world of small scale modelling. It is a double action, internal mix, gravity feed design which uses the standard top mounted trigger setup. External surfaces are covered in a brilliant chrome finish that is flawless. The brush uses the standard 1/8” airline fitting like the ones used by Iwata, Grex, Creos or Harder & Steenbeck brushes. Users with Paasche, Badger or Thayer & Chandler hoses will need appropriate but readily available adapters. The HG-SF features a 1/16th oz. color cup, an adjustable trigger assembly, adjustable needle stop and a solvent proof needle bearing. The retail price for the brush is $209.00 US dollars, but it is available from multiple locations for as prices close to half that. Spares are readily available in the United States through Coast Airbrush’s website though I can’t provide details for other countries.
This airbrush utilizes a small .20 mm screw in type nozzle and is made of a tough alloy and the needle is as finely crafted as other Japanese airbrushes. The HG-SF is roughly 6” (15.2 cm) long with a .45” (11.45 mm) diameter main body.
I have provided a picture of the standard breakdown of the brush. Pic 2
The EVALUATIONPhysical Details
The mechanical fit of all components used in the HG-SF is extremely good. Most threaded surfaces are chromed though some are in natural brass. The finishing of most internal parts is chrome and polished to a very high level. The exterior has a flawless chrome finish as would be expected of a brush with a suggested retail of over $200.00. The finishes on this brush produce are absolutely first class and are fully as good as the Iwata HP Series which gives a sense confidence from the first touch.
Even though the HG-SF has traits common to other brushes, this brush has it’s own unique feel and feature set that is very well thought out and executed. The balance and weight of this airbrush is very good as is the trigger action. The trigger is one of the highlights of this brush and is extremely smooth and very responsive. It has very little side to side play because it uses the captive pin style pivot point similar to the one used on the Olympos MP-200 Micron series brushes, which are renowned for their feel. Tension can easily be adjusted via moving the spring guide to match whatever resistance you prefer. Another, well executed feature on the HG-SF is the ungraduated needle stop. Pic 3 This item is great when you’ve got a lot of time invested in a model and you don’t want to chance pulling back too far on the trigger and ruining your work. It allows you to preset your spray pattern for maximum width and repeat it continuously for as long as you need to. The needle stop positioning is firm and consistent so if you bump the rear of the brush, you shouldn’t have to reset your needle travel. The 1/16th oz. color cup it totally in keeping with what is needed for a detail airbrush. It holds enough paint to do brush appropriate functions and doesn’t obscure the sight line when performing delicate work. The shape of the color cup is wide open and provides great access for cleaning and the lid that accompanies the brush is chromed metal and fits very tightly. There is no cutaway section in the rear handle for quick cleaning, but I don’t personally find that to be a flaw.
The HG-SF’s needles and nozzles are small and easily lost but are rugged enough for consistent long term performance. They are also very well machined and smoothly finished. The brush features a removable air cap that allows spraying very close to the surface being painted. Pic 4 Exercise extreme care if you choose to do so as the needle is very easy to damage if you touch the surface being painted. Replacements of these items are readily available but can be somewhat expensive when compared to some other airbrushes on the market. Should you damage these items the cost for both replacements together will run around $40.00. With normal use and care, I have never had to replace a nozzle or needle in this brush.
In Use ResultsThe HG-SF is definitely considered a detail airbrush. Its .20mm tip is regularly used by those who are pre or post shading a model, spraying free hand camouflage at low pressures or airbrushing highly thinned paints or inks for area washes, weathering or filters. While it can be used for applying paint to larger areas, it will require more coats of paint to achieve good coverage and it will require substantial patience when compared to the general purpose brushes with larger tips. This is not a design flaw, just a consequence of the design choices needed to produce very fine atomization and small clean lines. As with all detail brushes, a little paint goes a long way.
The first paint used to evaluate the brush’s performance was Vallejo Model Air. Pic 5 This paint is packaged in dropper type bottles and is advertised by the company as being “airbrush ready”. The paint was shaken well, put into the color cup and sprayed unthinned at onto a piece of clean Evergreen sheet styrene. The Vallejo paint sprayed with a somewhat grainy pattern when covering larger areas. Pic 6 This indicated less than optimal atomization so I experimented with variations in pressure to ensure best performance. Best atomization of the unthinned paint through the HG-SF was achieved at 15-18 PSI (1-1.25 bar). At this setting, the airbrush consistently sprayed patterns of 3/16” (4.1 mm) with minimal overspray but it still displayed a slightly grainy spray pattern. Overspray increased dramatically when lines above this size were attempted. The smallest lines achieved without thinning were .012” (.31 mm) and were achieved at the same pressure. Tip drying was a huge issue when spraying Vallejo Model Air unthinned. Maintaining consistent performance was a chore as spraying more than 2-3 seconds would cause degradation of spray pattern. Pressure changes did not improve this situation.
The airbrush was cleaned and a new Vallejo Model Air mixture thinned 3 parts paint to 1 part Vallejo 71.161 Airbrush Thinner. Pic 7 With this mixture, the HG-SF sprayed best at 12-15 (.8-1.0 bar). The wide spray pattern was 5/32” (4 mm), but the amount of overspray and graininess was much less. Pic 8 The fine line work with this mixture was improved, achieving unbroken lines of .007” (.18 mm) with very minor tip dry and no overspray. Clearly and as expected, the .20mm tip performed better with thinner paint. Pic 9 I did try thinning the Vallejo and dropping the pressure more, but the paint lost its consistent spray pattern and controllability.
The next paint I used to evaluate the HG-SF’s performance was Tamiya’s standard acrylic line. Pic 10 Tamiya’s paint is not “airbrush ready”, so I thinned the initial batch 1 part paint to 1 part thinner. This 50/50 ratio is a common mix recommended by Tamiya when using their X-20A thinner, so I used it as a starting point with the Tamiya’s yellow top lacquer thinner as well. Pic 11 I use both of these thinners when spraying Tamiya paints since there are times when I want more “bite” than the X-20A will produce, such as when spraying base coats or on bare plastic. I use X-20A when I need to lay acrylics over enamels without damaging the base coat. I use the same thinning ratios regardless of which Tamiya thinner is used. The 50/50 mix sprayed well with good atomization at 15-17 PSI (1-1.2 bar) but displayed a good bit tip dry. Pic 12 The airbrush produced a consistent 5/32” (4mm) spray pattern which was easy to maintain and had a minor overspray. Fine line work yielded a .010” (.26mm) line that was repeatable, with good color saturation but when pressure was pushed higher or lower, the results became inconsistent.
Increasing the ratio of thinner to paint to 2 parts thinner to 1 part paint yielded much better performance. This mixture is pretty close to the famous “thin to the consistency of skim milk” recommendation that most airbrush users are familiar with. I was able to produce a repeatable 5/32” (4 mm) wide spray pattern, but the atomization was substantially better than with the 50/50 mix and I would classify it as very good. Pic 13 Fading and shading were seamless and fine lines of .006” (.15mm) could be maintained and repeated at pressures between 10-13 PSI (.7-.9 bar) without tip dry. Pic 14 Additional thinning of the paint is possible on primed surfaces but thinning the paint more resulted in spider webbing and uncontrollable lines since I was painting on bare plastic.
CleaningFor the cleaning step, I emptied the reservoir, filled the cup with appropriate thinner and used an old paint brush to swab the cup and get into the recessed area behind the nozzle inside the color cup. I sprayed until the output of the brush was clear and then followed up with a lint free wipe to finish the color cup. The needle was then removed and a solvent soaked interdental brush was run into the needle bearing to remove any debris that might be pulled back into it when the needle was removed. I will mention here that the wide mouth, precision machining and superb finish of the color cup makes this one of the easier to clean brushes that use the screw in type nozzle.
CONCLUSIONThe Tamiya HG-SF is a superb airbrush. It offers very good atomization with properly thinned media, excellent detail potential with model paints, good ergonomics and function. The body diameter makes the feel somewhat like a better balanced version of the Iwata Eclipse with spray capabilities like the Iwata HP series brushes. This is not another clone of the HP series, it is a brush that is designed and built for its intended purpose. While parts availability is a challenge for those who prefer to buy parts locally, the wonders of internet shopping can make this brush viable for pretty much anyone. If you are in the market for a detail airbrush, I would highly recommend you include this airbrush in your consideration and if you decide to go with this brush shop around for best price!
Next up is another popular brush focused on the modeling community; the Badger Krome…