Spray Painting Advice/Tips for a Rookie?

[Glomar]

This is a VERY basic question, but I have never used spray paint before so I am hoping to benefit from all your collective knowledge. Any tips, advice, cautions that you have for a rookie? I have been looking on youtube, and there is a lot of great vids regarding plastic models, but I was curious if there are any considerations for working with wood (ie: clear nail polish under tape to prevent bleeding)  Probably being a little neurotic but I am pretty far along in my first substantive build and really cautious about messing something up. Appreciate the help as always! 

[Oldsalt1950]

Make sure the surfaces are clean and dust free, use a tack cloth to clean. Just press the edge of the tape firmly against the surface of the hull no need to put anything under the tape edge. Use a good quality masking take. and don't leave it on the hull too long. Test your spray pattern and air pressure on a piece of scrap. It will also allow you to determine how far away from the surface you need to be. Start spraying before the area you want to paint, and let up on the paint after you have cleared the end of the area to be painted. Less paint per pass is better than too much. It will take a few tries before you get everything dialed in and can actually start laying paint on the hull. I was an aircraft finishing painter for Fairchild-Republic and that is what I learned . 

[Bob Cleek]

I think you are basically asking how to paint, because once basic painting is mastered, spray painting is just another way of putting the paint on the piece you want to paint. Total mastery of painting is a broad subject well beyond the scope of a single response on an internet forum. I'll just offer some general advice I've found helpful. No doubt others will chime in to disagree and then you'll be more confused than ever before!  

 

You have to learn to walk before you can run. Spray painting requires a command of basic painting techniques to do well. None of the common challenges and problems encountered spray painting can be overcome without a basic understanding of coatings and their applications. The most important thing to master with spray painting is control over the amount of paint you are applying to the surface. Too much paint will result in runs, sags, and "curtains," which will ruin the job, require wiping off the uncured coating with solvent and re-prepping the surface or waiting until the paint is fully cured and then resanding to perfect fairness.

 

First, I would not advise that any serious modeler use rattle can spray paint for much of anything, except perhaps a sanding basecoat. The quality of the nozzles on rattle can paints, while remarkably good considering the manufacturing tolerances required, aren't good enough for the finish perfection scale modeling requires and are primarily designed for spraying large areas, not small ones. Besides, if you need just a small amount of paint, you're stuck buying the whole rattle can which, like as not, will "die on the shelf" before you get around to using it again. They are also an expensive way to buy paint. If you are interested in spraying paint, the sooner you acquire an airbrush and learn to operate it, the better. It's not rocket science and the cost of a basic quality airbrush and small compressor will be quickly amortized in paint cost savings. If you can't afford an air brush, then learn to paint with a quality bristle brush. An experienced painter can achieve the same results with either application method. (The airbrush is more forgiving in covering large surfaces, but others may have found otherwise.)

 

It is essential to learn how to properly "condition" your paint to achieve perfect finishes. This is done with thinners, "retarders" (that slow drying and so permit brush strokes to "lay down"), and "accellerators" (which speed drying to prevent runs or "curtains.") There are also additives that will achieve the finish desired from high gloss to dead flat and anywhere in between. The consistency of the coating is a major determinative of the quality of the job. Learning to condition paint is a process of acquiring "hands on experience." If you know someone who knows how to paint, getting some one-on-one instruction would be helpful.)

 

Learn how to work with the medium you choose, be it solvent/oil-based paint or water-based acrylics. Learn to use sealers (shellac, etc.), sanding base coats, and finish or "top" coats. Learn how to mix colors from a basic pallet. (Study the "color wheel.") There are hundreds of pre-mixed colors available in tiny bottles with high prices. Use these if you wish, but realize that tubed paste artists oils or acrylics are the basic building blocks of all those pre-mixed colors and if you "roll your own" you will save a lot of money and rarely find yourself running from hobby shop to hobby shop (often far and few between) or waiting days for the arrival of an internet purchase to find more of that particular color you just ran out of which may or may not be still available.

 

Remember that painting anything is 90% preparation and 10% application. Especially in modeling, surfaces should be perfectly smooth (or textured as required) and perfectly clean before the paint is applied. And if you use brushes, learn how to clean and care for them so they don't become "dust applicators" that ruin what otherwise would have been a perfect job. Cleanliness is essential. Store masking tape in zip lock bags and never lay a roll of masking tape down on its side. The side of the tape roll will pick up every bit of dust it contacts and ruin the tape for producing the perfect razor-sharp lines sought in modeling. (Buy quality 3M "fine line" tape or Tamiya masking tape. These tapes will produce the sharp lines required for modeling. Household "painter's tape" is not suitable.) Use a "tack cloth" to remove sanding dust from a piece before painting it. Store your tack cloth in a zip lock plastic bag, too. Try to paint in a dust-free area. While often easier said than done, painting on a dusty  workbench where you've just sanded the piece in a room with dust hanging in the air is not advisable. 

 

Unless you are completely familiar with the coating material you are using, (meaning you used it recently,) always, always, always test your materials and surfaces before committing to painting the workpiece. Paint can thicken or even lose its ability to "dry" while sitting on your shelf. (The modern synthetic coatings can be quite finicky in this respect.) Colors will often appear different when "dry" than when applied. Sometimes coatings are incompatible and disasters will result when they come in contact with each other. By making a test strip using the same surface, including undercoats, to be painted and the paint you want to apply to it, you can determine what the results will be. Failure to do so can result in a hull that is coated with a dirty, fingerprinted, sticky mess that refuses to dry and must be laboriously stripped off down to bare wood before another attempt can be made. 

 

 

Edited June 8, 2022 by Bob Cleek

[DocRob]

Many good advices by Oldsalt, Glomar. Airbrushing is about a certain discipline. It's not overly hard to learn, but you have to train a lot, to get decent results. Try everything on paper or an old model first. Keep the airbrush clean at all times and care for your needle. A bent needle will result in bad spraying. 
One thing can't be emphasized enough, the mixing ratio. Almost all colors have to be thinned. The rule of thumb calls for a milk like mix to spray. Again, this has to be tested. To thick mixes will clog in the airbrush to thin mixes run under masking and don't cover. 
Try to get adjusted to the medium you spray, acrylics, enamels or whatever. Use the appropriate thinner for the color.
When you have found the possibly correct mix of color and thinner, experiment with the air pressure, until you have the right balance.
When you spray, try to avoid start spraying onto the model surface, start before and stop, when moved over the area completely.
If there is dotting, you may have color clogged on the needle. This can be easy cleaned off, but can be a sign of a to thick mix or to high air pressure, specially with high pigmented colors.
Airbrushing is 80% preparations, masking and cleaning and at max 20% of spraying. Be patient and analyze what you achieve.

 

One word about masking, there are several possibilities, the one I like most is yellow Kabuki tape, which you can purchase from different producers. It's thin, adheres well and can be cut very precise. Sometimes you will need liquid masks or flexible masks for achieving contours.

Do yourself a favor and wear a respirator mask and rubber gloves, when airbrushing. Almost all mediums you spray are poisonous or dangerous.

 

If you have more specific questions, I will answer you for sure and don't forget, airbrushing is fun and a great technique to have mastered.

 

Cheers Rob

[Oldsalt1950]

Glomar, I assume you are going to be using an air brush. Do you have your equipment yet? If so what size needle, and is the air brush dual action? If you are using an air brush start at 30 psi which should give you plenty of control, you can then adjust paint flow for a specific distance from your model. The distance away will determine the amount of area covered. As stated earlier too much paint and to close will produce runs, sags and what is known as curtains. To far away produces orange peel as most of the paint is drying before hitting the surface to be painted. A clean paint gun is a happy paint gun and will give you no problems and last almost forever. Acrylics are easier to work with than solvent based paints, but may require more thinning. A mask like the paper ones worn during the Covid crisis is highly recommended as there will be fine particles in the air. If you need to hasten drying time a hir drier will do the trick. One thing you will also have to remember is to use overlapping spray patterns and very light coats. Better to apply to little paint than too much. You can always add additional layers, but removing excess paint is a real PITA. Don't just practice on flat surfaces find an old jar or tin can so you can practice on curved surfaces too. They are a bit trickier but once mastered you can spray paint anything. Keep the manufacturers literature on your equipment, as they have cleaning directions and usually an exploded view of the equipment if the need for disassembly occurs.

[Glomar]

Thanks for the amazing advice everyone! @Bob Cleek you pretty much wrote a dissertation on painting right there so might be getting on my to mastery soon! 

@Oldsalt1950 I am actually going to be using a rattlecan to paint the antifouling as thats what Bob and James use for their Vanguard series (specifically plastikote red oxide.) I do have a little airgun set up but I could not find the right shade of red oxide available (paint stocks are LOW right now) so just decided to try a rattle can. 

 

In regards to cleaning, what is the best way to ensure the surface is prepped- is it enough to wipe it down with a tack cloth or do I need to be more aggressive? 

Do you all typically sand between coats?

I really appreciate all the insight! I had very little modeling/woodworking experience but thanks to this community I am REALLY getting close to finishing the Nisha. I am building the model for my Dad so trying to make it as close to perfect as possible. 

[Oldsalt1950]

I use a tack cloth and the air brush (air only) to get all the sanding dust and accumulated dust and dirt off the ship. a light sanding between every few coats is usually indicated. You will be able to tell rather easily when sanding is needed. Be sure and look at the paint job from every angle to see where there may be too much or too little coverage. 

[Knocklouder]

Hi I read most of this thread, my two cents is  when masking the area you want to paint,  take a putty knive an run it along the edge to take the air bubbles out to help prevent bleeding under  the tape, practice  practice  practice   🙂 😊 

[allanyed]

On 6/8/2022 at 1:57 PM, Glomar said:

(ie: clear nail polish under tape to prevent bleeding)

This is great advice.  You can also do this with initial clear coat spray to seal the edges before spraying color.  One other thing that I learned from a lab techie when I worked for PPG Industries coatings and resins division ----do NOT ever start the spray on the object.  Start next to, but off the item to be painted then move steadily laterally across the item and continue until you are PAST the item.  If you start and/or stop on the object the spray will be uneven.

Allan

Edited July 13, 2022 by allanyed

[Bob Cleek]

4 hours ago, allanyed said:

This is great advice.  You can also do this with initial clear coat spray to seal the edges before spraying color.  One other thing that I learned from a lab techie when I worked for PPG Industries coatings and resins division ----do NOT ever start the spray on the object.  Start next to, but off the item to be painted then move steadily laterally across the item and continue until you are PAST the item.  If you start and/or stop on the object the spray will be uneven.

Allan

Excellent and essential advice! Additionally, don't airbrush by bending your wrist to cover a distance. Keep the airbrush at the same distance to the surface as you move the airbrush across the surface with your arm, not your wrist. If you spray with a "flick of the wrist," the center of your arc will be closer to the nozzle than the ends of the arc and you'll have an uneven lighter coat at the ends at best and, at worst, a big runny mess in the middle. Similarly, when spraying a curved surface like a boat hull, be sure to keep the distance between the nozzle and the work surface constant to ensure an even coat. It takes a bit of mindfulness at first, but quickly becomes second nature.

Edited July 14, 2022 by Bob Cleek

[DaveBaxt]

Not sure if this should be added to the other thread currently running. When using an airbrush can we apply shellac to seal the wood prior to using Acrylics or do I need a prime and I am assuming shellac can be thinned with methalated spirits or ethenol?I am assuming then ordinary surface primers such as made by Tamiya or Vallejo can be airbrushed prior to using Acrylics on metal? I then come on to using varnishes and can these be applied over the paint( to protect it) by airbrush too and if so what are these thinned with. I apologize as these are a number of questions which has been playing on my mind.