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Painting your Plane As a point of discussion let me offer that the most frequently asked question of us when we attend shows and the like is "Can I really paint my own airplane?" My quick answer is "yes you can" but there are several things you need to take into consideration. There is no substitute for experience and if you haven't been exposed to spray painting you need to get some hands on experience before putting that final finish on your new bird. One thing I can guarantee is that almost nothing that I can think of is more rewarding than looking at a project that you finished yourself and because spray painting is fun, I encourage you to bite the bullet and 'do it yourself'. The things you will need begin with good equipment. HVLP spray equipment is the best for the job nowadays no matter what anyone tells you. HVLP offers low overspray, no moisture problem and only uses half the amount of paint that conventional systems do. We also strongly recommend a good supplied-air-respirator to wear when you enter that toxic painting environment or you will wish you had. Breathing the stuff is deadly - don't rely on any type of filtered respirator. We want you to be alive and well when it comes time to fly your new plane. We sell the Hobbyair and Citation systems which are safe and reasonably priced but whatever kind you choose - get a good one. Look at the spraygun when you choose HVLP equipment. Poor quality guns make for poor quality finishes. A three stage turbine is the best choice for power - you will need as much as you can get. The three stage turbine puts out about 5.5psi to the pressure pot which is just enough for fine paint atomization like polyurethane. Consider protective clothing as well as breathing protection. When you start spraying you will be glad you had on a protective paint suit, hood, gloves and even shoe covers. HVLP offers a real advantage in overspray but still you will want to be fully protected. When your spray system arrives grab the instruction manual for the spraygun and see how its put together. Work with the various adjustments that it has. Now take it apart and see how it goes together so you will be able to clean it easily. Finally, fill the cup 1/4 of the way with an inexpensive lacquer thinner, hook it up the spray hose and, assuming you are in a ventilated painting area, see how it sprays while making fine adjustment to the gun. You are now ready to begin your hands-on education. Wash Primer Careful consideration should be given to the substrate that you plan to paint..As most reading this will be constructing metal airplanes I will address the steps necessary to paint that type material so it will be protected for years to come. Here is the sequence:
On aluminum it is vital that follow these steps so that, when you are finished, you have a beautiful and fully protected airplane. I will go through the products and process step by step so that you understand, not only how, but why I suggest the above materials and it is important that they go on correctly. The tips offered herein are gathered over years of painting experience which others in the field have gratiously offered. How to apply: Before this product was available, it was necessary to use an acid etch material and then alodine to prepare the surface but this wash primer provides both in one application. Use a 1.0mm needle and nozzle in your spraygun for spraying this material. A little practice on a test panel will be helpful and you will see that this is a no brainer - it sprays very easily and will help you build confidence for the coming coats which I will discuss as we go on... Primer For the kind of products you will be using and the kind of painting you will be doing, you won't need to change needles and nozzles. The 1.0 mm will do a nice job atomizing the products with an HVLP three stage turbine delivered to the spraygun through 40' of airline or less. So lets not complicate the process by changing needles and nozzles. You will need to keep the spraygun clean between sessions, however, and this is accomplished by pouring out the material from the paint cup and adding about 1/4 of the cup with lacquer thinner. Spray this thinner through the gun until the spray is clear - then remove the nozzle from the gun and clean in solvent and replace. Don't let paint dry in the spraygun! You will never get it all out if it dries and specs will continually come out of the gun in future paint applications. Now that you have the wash primer on it's time to apply the primer. Various types are available but most prefer a good quality epoxy 2 part primer like DuPont DP 40 or similiar. It is easy to apply and provides an exceptional tooth for the base coat to grab onto. What's the primer do? It has two primary purposes - it fills in minor defects in the surface to be painted and it acts as a magnet for holding on the base coats by absorbing some of the topcoat material into itself. This absorbtion quality doesn't just absorb paint, however, it will absorb dust, oil and other contaminants from the air so it is necessary to get the topcoat on to it in a short period of time - usually within 24 - 48 hours. Also, if you wait longer than that time, you will need to sand the surface of the primer because it hardens with time. Every painter has his/her own techniques for spraying and the following recommendations are what I do - others will have their own opinions which they are free to discuss here but I select a good epoxy primer which is either dark green or gray in color. This is because the first base coat color I put on is white. I choose white because pastel colors look much more vibrant when they have a white undercoat. And when I use a dark primer I can easily see where I am going when apply the white material. I mix the primer according to the directions on the paint can except that when using HVLP turbines I need to keep one feature of the turbine in mind - The turbine air gets hot!. This heat evaporates thinner which must be compensated for. This alone is the single most mis-understood fact about spraying with HVLP turbines. If not addressed you will get the dreaded orange peel - no doubt about it. So we need to add more thinner to the paint to compensate for this loss and a good rule of thumb is 30% more!!! I recommend that after mixing test a sample of it on a test panel - then, when you have achieved an ideal mix get out your Zahn cup and time the mix. Future batches will be not require testing once this is achieved. Now that you have a proper mix and you have all the necessary protective gear on and your mask is supplying a comfortable amount of fresh air to your lungs, you're ready to go. Stretch out the hoses to the work area so they won't kink around any obstructions and you're ready to begin. Remember - hold the gun about 8" from the surface and keep your wrist locked. Your shoulder will move the gun from side to side and up and down keeping it the same distance from the surface at all times. We have already talked about adding more thinner to the paint which is the first all important requirement when spraying with HVLP and now the second requirement: Spray on a mist coat first: Mist Coat It's going to be more important on
the base coat than the primer
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