Londons Autobody

A Closer Look Into Painting

Each and every spray systems is made up of three crucial parts: a compressor to pressurize the paint, a container to hold the material and a spray gun to spread it across the required surface through its nozzle in a fine mist. The process of painting by use of compressed spray gun is very simple. On pressing the trigger switch, Ventury effect gets formed, and the paint combines with the compressed air releases itself into the surface as a fine mist.

Different spray painting techniques are employed to paint the surface of a car and all of them use compressed air or fluid or air pressure to discharge and direct the spray. Spray guns are commonly used for spraying cars. Spray guns have two main classifications: suction fed and gravity fed. Both are easily identifiable from its shape and the way it is arranged. In suction fed spray guns, the paint container is fixed below the air gun and compressed air is used to attain the desired spread. It also has a dedicated air cap to generate low vacuum. In gravity fed, the container is at the top of the gun and the major force acting on the system is gravity though compressed air is used to a lesser extent. Gravity fed spray guns are capable of giving good performance than suction fed guns, as it uses less compressed air and has less weight.

Another process is the HVLP or High Volume Low Pressure system. Though akin to spray guns as far as the compressed air is concerned, the gun works at low pressure. The effect is that wastage is minimized to a large extent.

A third process uses Low Volume Low Pressure or LVLP system, and is an improvement of the HVLP system of painting. Here wastage is further controlled and the intended surface gets more paint. Both HVLP and LVLP system need high capacity compressors and may not be ideal for every day use.

In Electrostatic Spray painting, paint powder is used in this technique. When the paint is discharged from the gun, it is so arranged that it develops an electrostatic charge and is sprayed to the oppositely charged surface. As the minute paint particles repulse each other, the area covered by the paint is much more than other systems.

It is important to adhere to safety norms as fine mists of paint are formed and gets released into the air.

Tags: Compressor, gravity feed paint guns, HVLP, painting, spray guns, Spray paint, spray patterns, suction feed spray guns

How To Repair Fiberglass Cracks On Boats

Discovering fiberglass cracks on a boat is every boat owner’s nightmare. Although fiberglass can be considered as a sturdy type of material, cracks cannot be avoided due to the constant stress a boat can encounter on sea. Every year, maintenance costs can set back hundreds of dollars on a boat owner’ wallet. But this need not be the case anymore. If you’re a boat owner looking for a way to maintain your boat without having to spend so much money on it, then why not learn how to repair fiberglass cracks on boats yourself?

Do you want to know how to repair fiberglass cracks on boats? Then you need to need to know the basics about fiberglass first. You have to understand that the advantage with fiberglass is that it is one of those materials that are easy to fix. You don’t need to order in special supplies or tools just to get started. Most of the things you will need to know how to repair fiberglass cracks on boats are readily available in your tool shed.

To get started, you have to check the cracks on your boat if it is just a simple stress crack or if it is a void. It’s really easy to differentiate between the two. A stress crack looks just like a crack an eggshell could get. As soon as you find a crack on your boat, try to get it repaired immediately so that the crack will not cause further damage that will be more difficult to fix. As for a void, you’ll be able to assess a void by touching it. If it feels like there’s a dip on any smooth part of the boat, then most likely it is a void.

Knowing how to repair fiberglass involves having a little know how on how to use a sander or buffer. A sander or buffer is needed to ground out the stress and any other damages the boat has achieved. After achieving a smooth surface on the damaged part then it would be the perfect time to start applying the new fiberglass. Always follow instructions included with different solutions you’ll need so you can start applying the new fiberglass. Make sure you choose a crack sealant that is both affordable and very effective so you are able to get your money’s worth.

If you’re an avid sailor, knowing how to repair fiberglass cracks on boats can prove to be a very essential skill. As long as you have the right tools, supplies and a positive mindset, then you’re all set. Not only will it save you hundreds of dollars in repair bills, but it also gives you the fulfilling feeling of being able to fix your won boat.

Roberto Bell

Please click these links if you want to know more about how to repair fiberglass cracks on boats or how to repair fiberglass cracks on boats in general.

Tags: boat repair, body filler, Bondo, fiberglass cracks, fiberglass mesh, fiberglass repair

Bondo Basics – Apply and Sand

Bondo Basics – Apply and Sand (part 2)

This is a follow up to:  Bondo Basics – The Art Of Body Filler

When applying and sanding bondo your gonna want to be fully assured you know what you’re doing. This will save you time and materials in the long run. Don’t bother starting with the bondo until you have made sure your damage is pulled, patched, ground down, blown off, wiped clean and ready.

To Begin you have to make sure your area you are applying the body filler to is completely roughed up. Grind the area thoroughly with 36 grit sand paper or at a minimum of 80 grit. Take your air gun if you have one and blow off all the dust and grit from grinding. There are steps people like to avoid, I’m guilty too, but you learn some shortcuts pay and some don’t. Here’s one commonly overlooked. Wipe it down. Take the wax and grease remover and treat it as though you were painting it. The bondo has to stick completely or it will chip and flake, in other words it won’t feather for you and it will tick you off and waste time and materials. If your damage is repaired right you shouldn’t have to apply more than two or three coats to have a finished repair.

Alright, to the tools needed. Generally you want a 5 – 9 inch sanding block. The sandpaper you need will be the common 36, 80, 120 works well sometimes, 180 then 320 for feathering before primers etc. A DA Sander is used by some, but the same sandpaper applies, choose the same grits.

The methods: Depending on the size of the damaged area, mix only enough to fill the damage completely. Be sure to apply enough – this takes a little to get used to. One important note is that you will not spread the bondo perfectly, it shrinks in an you will end up with a low spot. Apply enough body filler so it’s built up a 1/8 or so. Not more than that, you will be sanding your butt off, this gets old Take your 36 grit or 80 grit, depending on the amount  of area you will be sanding. If you think you can lightly sand and feather in one or two coats, then stay away from the 36 grit unless you know when to stop. It puts some pretty deep scratches in the bondo and the area around the bondo where you will be sanding over. Use 80 grit to avoid excessive scratches. For most larger dents you will want 36 grit and your larger or largest file board.

With the panel prepared and the bondo spread,  let it harden. If you have a mess you can carve on it with a knife to get some of the stragglers you slopped on it off. If you wipe on body filler when it is not set up it will surely stick and you’ll have to sand them off. Let it harden and pick it off later.

For large dents that you know will need at least 3 coats of body filler it’s best to have a rasp or body file hand plane. It works somewhat like a cheese grater. Let the bondo set up real good, feel the bondo and it should be a little warm but not cold….if it’s cold it will be too hard for the rasp if it hardens.  Take the plane and begin filing in one direction. This is very rough but effective way to cut your panel. This takes a little getting used but it will save you quite a bit of time, sandpaper and your lungs from tons of dust. Use it on the first coat only, the rough coat. You will be turning right around and spreading another coat of bondo over it, after you blow it off real well of course . This is used to help get the filler straight. The low spots will not be filed. Note: To help Identify the low spots… spray the filler with a cheap flat black paint, the cheapest fastest drying kind you can find. DO NOT USE ENAMEL SPRAY PAINT, you don’t have all day to let it dry. Find a cheap lacquer paint, Walmart brand works good at .94 cents a can. Simply dust it, don’t put a full coat of paint on, just enough to add contrast to the body filler to identify where you have sanded. This will greatly assist you identifying what and where you are  sanding. High spots are gonna sand first of course. Keep attacking them as you sand until  all the guide coat paint around them is off. If you have sanded the filler and panel is free of the spray paint you applied, chances are you are real close to a finished repair. But there are other things to look for and consider.

Take your inline sander or manual long board of choice or hand sander and begin sanding in a criss-cross (X) pattern. This is extremely important if you do not want waves. Sand at a 45 degree angle in all directions to each other. This helps cut the filler evenly. If you sand in a straight line…. you get a straight line. This is not rocket science and there are no tricks. You have to watch what you are doing. Don’t go nuts sanding, do it methodically. Sand And Feel, Sand And Feel. Pay attention to body lines. They will have to be included in your sand and fill process. For straight lines use tape and sand up to it, reverse and sand down to it. Use tape when applying bondo to get a straight line. Apply the body filler over the edge of the tape and remove the tape before it hardens. If the filler hardens you’ll be sanding the tape too, so pay attention.

Apply bondo as many time as it takes to fill the low spots. If you have high spots you’ll know it. If the metal is showing and the bondo isn’t sanded… you have high spots. These will not go away. There are two ways to deal with this, only one is the right way. You can fill the whole panel up with body filler and sand and sand, or you can take your pick hammer and carefully tap them down. Tap them down!!! Don’t be afraid to use the hammer, you will need it until you are finished and satisfied. Don’t cheat, if it’s high… tap it down lightly…tap, tap, tap.  All the bare metal showing is high so tap the bare metal and beyond an inch or so. Stop sanding if you see this, they won’t go away and you’ll be getting further from straight. You’ll have to tap them all down and apply more body filler.

When you know your getting it close switch to the light grits. Use 80 grit paper and feather all the edges of the bondo and the paint together. It may feel a little rough and that is normal. You are filling the dent, the primer you use next will take care of the small scratches.

Another note: When mixing the bondo try to avoid flipping it over like taffy. Roll it over and spread mix it. You don’t want to let air get trapped in there. You will end up with pinholes eventually. Pinholes are just that. Small little pits in the bondo. These can be filled later with a glazing putty, but try to avoid excess air when mixing.

After the 80 grit sandpaper begin to taper down on the sand paper. Use 180 to feather any scratches in the paint near the filler. Finish with 320 to assure you won’t have sand scratch swelling later on down the road. The smoother you get the panel from here on out the nicer the repair will be as a finished project.

Wipe it down, look for pinholes, fill them with glazing putty if you have them. If not get that primer ready and spray on 3 good coats. Dust your primer with the black spray can and begin sanding again. I’ll write about the primers next.

Good Luck with your project. You’ll learn from experience, you can’t screw it up if you know these basics to bondo. It’s easier to do than explain

For further reading on Body Fillers  go here:   Bondo Basics – The Art Of Body Filler (part 1)

Tags: autobody techniques, body filler, Bondo, corvette repair, fiberglass repair, heavy weight gold filler, pinholes, sanding techniques