View Full Version : Spraying clear finish
04-25-2003, 09:31 AM
Okay, spring appears to be really making an effort here, so it's time to varnish the kayaks for the season. In the past, I've always brushed on Epifanes varnish and been essentially pleased with the outcome. This year, I have access to a sprayer, and would like to try spraying it on. Can anyone give me any pointers and pitfalls on the technique?
04-25-2003, 10:12 AM
Hmmm, I could show you but I'm not sure I could describe the method. Are you brand new to handling a spray gun or just unfamiliar with varnish?
Is it an HVLP gun or what I have, an pressure air gun?
What do you mean, clear finish? Varnish? Something exotic?
Thinning is a bit different with spray than with brush. There is a drip cup made to determine the proper reduction but I just do what my dad did, watch the paint run off the stip paddle until it looks right. Thats why I had to buff the orange peal out of the finish I put on our airplane.
Never pull the trigger unless the gun is moving and keep moving until after you release the trigger.
Protect your respiratory (nose hairs) system.
Guard against over spray. Neighbors may not notice clear finish on their car but they do barn paint. HVLP has much less overspray.
A very light spray allowed to flash off followed by a medium spray will be less likely to run than one medium spray with some finishes. I've not sprayed varnish but have System Three's WRC product.
What kind of set-up do you have??? If it is a Wagner Power painter that a friend lent you please give it back!!! I'm a professional painter and can hold your hand to do it right. So the first couple of things are 1. what kind of material. 2. what kind of sprayer do you have. Drew. :eek:
04-25-2003, 11:14 AM
The sprayer is a Turbinaire 1135 HVLP. The material is Epifanes Clear Varnish.
04-25-2003, 12:19 PM
That machine is too modern from me so it's up to Drew.
Another thought though is roll and tip may be faster considering clean up.
04-25-2003, 12:43 PM
With thousands of hours behind all kinds of spray guns, I can tell you............ what Norm says in his first post.
The reality is you can't be taught through this forum. You can be successful though, if you're willing to practice/experiment some before taking on the actual project.
Successful spray painting requires you to strike the correct equilibrium between: the equipment you're using, the material, air pressure, amount of reducer, temperature sensitivity of the reducer, ambient temperature when spraying, air movement in the spray area, and application speed. Got it!? Practice, Think, Pray! (Sorry, Norm! :D )
04-25-2003, 04:44 PM
I'm actually pretty good at roll and tip application, but want to give spraying a try. I'll practice first on someone else's boat, and after that try it on my own.
If anyone has any tips to share, I'm all ears.
04-25-2003, 06:54 PM
In a nutshell, the trick to spraying is to reach the point where the material you're laying down is wet enough to flow out to a flat, glossy surface, but dry enough so that it won't run. The challenge comes from the fact that while there is one ideal outcome, there are many, many ways to get there depending on temperature, material characteristics, the gun, etc. It really is nearly impossible to discuss in a meaningful way without referencing specific products and conditions.
I've taught a number of people to spray, and find that they either have a sense for what they are trying to achieve, or don't, and it can't be taught at the higher levels. If you've had success with roll and tip, you already understand the issues involved, and will probably be able to develop a talent for spraying. Top gun handlers in the Seattle automotive market are paid upwards of $125k a year, so if you get really good you've got a professional level career! Good luck!
04-25-2003, 08:05 PM
Ditto all the above. Also with thousands of hrs behind a gun, I must add that there are few things as addictive as a perfectly sprayed finish. The other thing noone has mentioned is that it is the highest productive method of applying, with rolling following, after a certain break-even point (small jobs are best rolled, but if perfection is required, well . . ).
The Woodweb's professional finishing forum has high marks on the Turbinaire, though I use an Accuspray (got a deal on it). Easily twice the transfer efficiency than high pressure spray.
Without getting technical, here is what I would do if I were beginning:
Buy cheap polyurethane porch floor finish, grey, and some thinner. Practice spraying a sheet of plywood vertical. This is a tough test as runs will be more possible due to the slow drying, but that's what marine varnish will be like. Test with different levels of thinner. Two part marine urethanes may be easier to spray due to the faster drying. Slow drying means more sag potential. If your good after practice, you will get just the right amount so that you have build, but no sags. If I were you, I would add some kind of pivot rods to each end of the kayak and rotate it like a pig on a spit, as a "run chaser" as you are spraying all surfaces. I have experience with this technique when I was an application chemist in 100% solids radiation-cured (UV) clearcoats, and that creates the glassiest perfect finish possible by taking gravity out of the picture. The additional film build allowed swallows up any dust specs, and runs/sags are melted in. This is especially helpful if you are not good at spraying perfectly even film builds.
Another great beginner trick is to dial the material knob down to nothing, then while pulling the trigger slowly open up the material til you see a mist. Practice with this level, which is the highest atomization, until you get good enough to open up the valve more.
Also, let the turbine run for a while to warm up the air, then it will atomize better by lowering the viscosity of the varnish. - JB
Hi Lisa!! Drew here!! Look, it isn't rocket science. I have the same machine, but I use a Titan 350 HVLP because of the projection set changability. anyhoots, as was mentioned above, if you don't have a visq cup, thin your material alittle at a time, you know when it's right when you count one drop of material per second of the end of a paint stick, held at a slight angle. adjust your fan, top screw, till it is app.. 6-8" from top to bottom when you hit the trigger all the way in. The gun you have is a two stage gun, when you pull the trigger alittle, you get air, all the way in material and air. Test and adjust your fan and material on a piece of wood or paper etc.. until your fan is adjusted, and the material isn't a large splooge in the center. Practice a few passes about 8" away from the surface your practicing on, Now here's the "trick" to a good finish, sand,sand,sand,sand! Your end result is only as good as whats underneath. Use air and a tack rag before you apply any finish, their cheap 1.95 or so, and their great on removing fine surface dust. Make sure that that you don't whip the gun to and fro when your spraying, it's not a spray can of wax. Just try to keep your distance away from your project, and go alittle slow at first, after a few passes, you'll get faster, and if you get a run or two, don't mess with them you can sand them out after they dry. Drew. :eek:
The grass may be greener, but you still have to cut it!
04-25-2003, 09:02 PM
You most likely know this, but it's worth saying that some finishes are deadly when sprayed and require an outside air source. The two-part isocyanate-type LPUs, including clear finishes, fall into that catagory.
04-26-2003, 05:43 AM
The tack cloth is your friend.I make my own as I need them,by misting urethane on squares of old (clean) cotton sheet.To refresh,just mist more finish on.
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