Clear Coating and How To Do It!
Me and my SATA Mini Jet 4
The Art of Clear Coating : Kinds
If you are new to clear coating, you may be somewhat confused about which one is right for you. There are, 2 part clears, and 3 part clears. There are also speed clears
and conventional clears like house of Kolor Kosmic clear
. Speed clears are my favorite. I also use the conventional when it is requested, but my favorite are speed clears because they are only two part clears and can be cut and buffed to the shine of a three part in the time it takes a conventional clear coat to fully dry. All of the clear coats discussed on this page are to be understood as Urethane clears, not lacquers.
Pros and Cons of Two Part Clears
pros:
- not as expensive
- dry in two to three hours and can be cut and buffed
- can be buffed and polished to a show shine
- U.V. protectant to the underlying paint
Cons:
- don't flow out as nice as a three part
- more prone to orange peel and dry spray
- the time windows between coats must be very carefully followed.
Pros and Cons of Three Part Clears
Pros:
- three part clears have an excellent flow out when applied properly.
- they dry with a show like finish and often times don't need cutting or buffing and polishing.
- orange peel and dry spray are almost never a problem.
Cons:
- There are three parts, so more to buy and thus more expensive
- they take much longer until they are dust free, which means more difficulty with dust sticking in the finish.
- usually a couple of days until they can be cut and buffed if needed.
How to Mix Clear Coat
To mix clear you must either have a mixing stick or a mixing cup. But whatever you do, DON'T GUESS! So when you purchase your clear coat make sure and order mixing cups and a mixing stick. To use a mixing cup is very simple. Once you have the proper ratios poured then stir the mixture and strain the clear coat into your hvlp gun using a paint strainer
made for this purpose.
How to Spray Clear Coat:
The Gun Matters!
My first piece of advice is to purchase the most expensive gun you can afford. Clear is gun dependent; big time. A cheap gun will not provide the atomization necessary to lay down a really nice finish. Here you have two choices, a full size or a mini or touch up gun. Whichever one you choose, get the largest nozzle size. It's even a good idea to check with the clear coat specs to see what size of nozzle they recommend before purchasing a gun. More on Spray Guns
To spray clear is an art form. The problems that plague the clear coater are dry spray, orange peel, and of course, runs. NO let me take that back.
"Clear coating is the most difficult part of the custom painting process and is prone to every bad thing that could possibly happen."
So don't waste your time and money if you don't care about proper surface prep and immaculate cleanliness, both in the environment and on the surface. Make sure you mix your paints and clear in a clean dust free location.
When spraying, you must wear a paint suit, a hood or sock as well as gloves and a respirator. This is not only for your safety, but it prevents lint and hair from settling in the clear coat. But as far as safety is concerned, clear coat is deadly if inhaled due to the VOC's (volitile organic compounds) and the isocyanates. It is also highly flammible, so please, please, please..... Don't use any fans for ventilation unless they are explosion proof, hazardous location types.
When spraying , make 50% overlaps with each pass and make sure and follow through all the way past the edge to avoid dry spray along the edges.
I know it sounds obvious, but don't get too close and don't get too far. 6-8" from the surface is about right for an hvlp, you can be farther away with a conventional gun. Also make sure you are moving the gun fast enough across each pass.
Don't keep your wrist stiff but let it bend so that the gun stays perpendicular to the surface at all times. Too slow and you will get runs and sags, but too fast and you will get dry spray. Also experiment with different fan widths of spray. I have found that with my hvlp a flat vertical spray that is semi fine works best. I use a mini gun for motorcycle tanks and smaller objects.
Also wait the proper amount of time between coats. Don't rush, it will only cost you ten times the labor and time of just doing it right the first time. Keep the layers fairly light around bolt holes and any areas that will have something bolted to it. Make sure and mask off all bolt holes. I use a small piece of rolled up paper to insert into the holes or else an actual bolt. This keeps the clear coat from getting down into the treads. Lifting will occur when the bolt is screwed in if this precaution is not taken. Also, Too much film build up will crack or delaminate around such areas when the head of the bolt seats against the surface.
When you lay down the clear coat it should look wet. Lots of light is essential, and all good spray booths have that. You have to be able to see the gloss of the clear coat as it goes on. If you can't, you run the risk of runs or sags and even dry spray. Start with lighter wet coats and progress to heavier. I don't recommend any more than 4 coats in one spray session or else you risk solvent popping (little bubbles in the clear).
To re coat, I strongly recommend first scuffing the finish with 600 grit wet dry or else with a red 3M pad. Then follow by wiping it down with a mild de greaser, then tack cloth it off.
Runs and Sags
Runs and sags are a part of the game. A sag is better than a run, in my opinion, but both of them are unacceptable. To correct them, use a soft sanding block and six hundred grit wet dry sand paper. Wet sand only the run or sag at first until it is almost level with the surface then use longer strokes to melt it in. dry it off occasionally to see if it is flat. any shiny areas means that it is not level yet. Keep sanding until there are no shiny spots. Once you get it to that point you can either re coat or cut and buff to a shine again.
Some people, and I am one of them, use a straight edge razor to slice the run off as level to the surface as possible before sanding. To do this, lay the blade flat against the surface and slice off the run or sag. Be very careful when doing this because you can cut too deep and cause yourself serious problems that can even require sanding down to the base coat. This is a real bad thing if your underlying base is kandi which is very difficult to spot repair.
Cleaning up
To clean the hvlp gun use a good solvent like Kustom Shop's.
Spray through the gun and then thoroughly clean the inside of the gun with a gun cleaning brush kit like Mack makes. I use a ketchup squeeze bottle to spray out the inside of the gun, nozzle etc. I always remove the needle and clean it thoroughly as well. If you skimp on the cleaning you will regret it the next time you spray. Imagine chunks of old clear coat lodging in your brand new finish. It is enough to bring any custom painter to tears.
More on gun cleaning and air set up
So what are you going to need to get started? Get a complete list here.
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These are the cups I use. I love them because you can buy the lids to go with them, and they are really quite inexpensive. Oh, and don't forget the stir sticks! |
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Clear Coating Kits,Reducer, Hardner depending on whether it is three part or two part.
Mixing Cups or mixing sticks
Strainers - Disposable or reusable and stir sticks
Spray Gun or Mini Gun - I recommend an HVLP.
Air Hose and all of the fittings
Air Compressor- Check the CFM Ratings against the gun requirements before buying.
Spray Gun Cleaning Brushes- I recommend the Mack Kit with the bottle.
Rags
Respirator - must be niosh approved for isocyanates.
Gloves- Latex or Nitrile
Paint Suit- Lint free with hood is preferable.
Head Sock - The alternate choice to a hood. In my opinion better than a hood.
