ade
28-12-05, 07:02 PM
Got a PM from Christ (not the lord although he may think differently 8) ) asking about an old old old post that used to be on here about treating rust. thought I'd knock up a basic guide...
This is the Novas biggest weakness (that and dodgy security). It is a basic guide so feel free to add your own comments/suggestions/best tips.
If youre looking at treating rust then this should help you...
It all depends on how bad the rust is. The basic rule is if theres holes cut it out and weld up or replace the panel. Dont just fill it with filler - this will crack and eventually fall out.
If its surface rust (ie can be removed with some wet n dry) then just sand off, prime and paint (see below).
If it's deeper (ie you cant shift it all with a quick sand with 240 wet n dry) or the rusted area has pitted the metal, then -
- you need to remove all loose rust with a wire brush (or a burnishing tool that goes into a drill/dremel), this will make a rough surface finish - take the paint away about 3inches all around the infected area
- then treat with krust or similar (the important thing here is to keep it away from water), a couple of coats will be enough,
- if you can get it and have used before prime using etch primer or zinc primer for areas that will be in contact with water often. Etch primer bonds to the metal through chemical reastion making a tough surface.
- then smooth over with filler - use a good quality catalloy not cheapy stuff. Build up slowly in thin layers - tbh if its just surface rust, one pass should be enough.
- Allow to fully dry (see instructions - 24 hours in warm area preferably)
- Sand back using DRY wet n dry until you have a smooth feathered edge between the filled treated area and the metal. Its important to keep it dry as filler is pourous. Use grades of paper from 240 to 400/600. I find if a big area and using an orbital sander (ie rectangle b&q jobbie), the grade of paper can be doubled - ie if using 240 wet n dry paper on a sander, the surface will resemble something thats been sanded with 400 wet n dry - it just takes away the filler much quicker but leaves a smoother finish. Its also a more even finish
- Seal this with cellulose putty or similar (knifing putty) - this will fill the micropours (minute air bubbles). Allow to dry fully (see can for dry times) and smooth fully with dry fine wet n dry - 600/800 grade+.
- Mask off the area (remember to kay the paint around the area or leave a feathered edge where theres no solid masking line). If for example youre spraying a rear arch, youd mask off the door edge, up to the window lower edge and about 1/4 way up the rear hatch edge. mask off wheel arch, wheel amd bumper edge as well as the lights. this leaves ther whole 1/4 panel. A pro shop whouild probably repaint the whole side of the car for a proper colour match (see below ref red faded paint).
- Once your happy, degrease the area with panel wipe. This helps remove any silicone bits, dust mites etc causing the paint to react ewith the surface
- Then prime using relevant primer (not filler primer). You may wish to heat the panel slightly with a hair dryer (avoid direct heat) - just to warm the panel - this will help with trhe curing of the paint - especially if the garage is v cold. Dont get the panel v hot - just warm to the touch.
- For a pro finish, when the primer is fully dry, dust lightly with a speckle coat of black paint (spray far away and dust the area so its covered in little spots). This is called a speckle coat and when you sand back using dry 800+ wet n dry (dry) the indentented areas wont go as fast until you get down to their level. Once all dots have gone your area is level. Try and use a sanding block and keep your sanding paper clear of particles by tapping it clear regularly (use a compressor to blow it clean).
- Now - you may wish to reprime the area - and then smooth using 800 again. To "feel" the surface, place a cloth (j cloth) between your hand and the surface. If it feels rough then continue sanding.
- Once your happy, degrease the area again with panel wipe. This helps remove any silicone bits, dust mites etc causing the paint to react ewith the surface
- prepare your paint (either can or spray gun) - if using a can, submerse the can (minus spray cap) into a hot but not boiling tub of water to loosen up the paint. This makes it more fluid and it wont splatter. Fully dry the can before spraying - give it a good shake also as per can instructions
Then tack cloth the area just before spraying. This removes any last minute dust mites.
- Then spray - 1 even coat - start at the top and work down in horizontal strokes - overlap bottom or last spray line with top of new one.
Allow to flash dry (see can for time). This allows the solvent to evaporate before the next coat - also known as tack drying. Dont spray before this time otherwise solvent gets trapped in the previous layer and will react (ir goes milky, splits, cracks, doesnt dry etc)
- then apply another coat - do this at least 3 times
- Once fully cured (heat lamp about 7 hours - normal warmish garage about a week), smooth any specks with relevant wet n dry (1500 - use wet) - go easy though and watch edges/corners etc. If you have runs, flat right back and respray again fully.
- now if you dont intent to use lacquer you can buff up now (depending on size of area, a mixture of G4 compound and t cut is good with a polishing mop and or damp cloth) - or I find T cut and super resin polish is good for small areas. Just go easy and keep checking the area. Remember t cut softens paint and takes a fine layer off. Do it too much too hard and you'll get patch paint down to primer!
- If you intend to lacquer smooth off any nibs/dust specs etc, using 1500 wet n dry (wet), fully dry and panel wipe area. Dont worry about any matted areas - the lacquer will turn them into smooth shiney bits - just make sure you cant see any sanding lines. repeat the spraying technique - especially the tack cloth bit. The more layers you apply the better the protection and deeper the shine. Lacquer is the invisible layer that stops your paint from scratching, oxidising. When you t cut paint, you t cut a layer of lacquer. the more you apply, the longer and thicker the protection. Just go easy - its very thin and can run easily.
(for reference, lacquer is where pearl paints, glitter paints and other fancy paints are usually embedded onto a cars paint work - mixed in with the lacquer).
- Remember, depending on the area you may want to check for a colour match as paint around it may have faded (noticeable on red cars). Pros will respray the whole panel/side to mask this.
Also - I'd avoid using hammerite as an undercoat to protect areas if you intend to paint over it. Hammerite is an enamel based paint which reacts badly with some cellulose/2pak/acrylic based paint systems. It can bubble and crack when it reacts. Not what you want with a rust prone area.
If youre treating an area like a joint (ie in the engine bay seams or arch lip) make sure any seam sealer hasnt perished. If it has remove fully and treat again using red stripe or similar sealer. DON NOT USE SILICONE BASED PRODUCTS - these react with paint and cause annoying "fish eyes" - areas where paint wont stick.
Hope this helps
Ade
8)
This is the Novas biggest weakness (that and dodgy security). It is a basic guide so feel free to add your own comments/suggestions/best tips.
If youre looking at treating rust then this should help you...
It all depends on how bad the rust is. The basic rule is if theres holes cut it out and weld up or replace the panel. Dont just fill it with filler - this will crack and eventually fall out.
If its surface rust (ie can be removed with some wet n dry) then just sand off, prime and paint (see below).
If it's deeper (ie you cant shift it all with a quick sand with 240 wet n dry) or the rusted area has pitted the metal, then -
- you need to remove all loose rust with a wire brush (or a burnishing tool that goes into a drill/dremel), this will make a rough surface finish - take the paint away about 3inches all around the infected area
- then treat with krust or similar (the important thing here is to keep it away from water), a couple of coats will be enough,
- if you can get it and have used before prime using etch primer or zinc primer for areas that will be in contact with water often. Etch primer bonds to the metal through chemical reastion making a tough surface.
- then smooth over with filler - use a good quality catalloy not cheapy stuff. Build up slowly in thin layers - tbh if its just surface rust, one pass should be enough.
- Allow to fully dry (see instructions - 24 hours in warm area preferably)
- Sand back using DRY wet n dry until you have a smooth feathered edge between the filled treated area and the metal. Its important to keep it dry as filler is pourous. Use grades of paper from 240 to 400/600. I find if a big area and using an orbital sander (ie rectangle b&q jobbie), the grade of paper can be doubled - ie if using 240 wet n dry paper on a sander, the surface will resemble something thats been sanded with 400 wet n dry - it just takes away the filler much quicker but leaves a smoother finish. Its also a more even finish
- Seal this with cellulose putty or similar (knifing putty) - this will fill the micropours (minute air bubbles). Allow to dry fully (see can for dry times) and smooth fully with dry fine wet n dry - 600/800 grade+.
- Mask off the area (remember to kay the paint around the area or leave a feathered edge where theres no solid masking line). If for example youre spraying a rear arch, youd mask off the door edge, up to the window lower edge and about 1/4 way up the rear hatch edge. mask off wheel arch, wheel amd bumper edge as well as the lights. this leaves ther whole 1/4 panel. A pro shop whouild probably repaint the whole side of the car for a proper colour match (see below ref red faded paint).
- Once your happy, degrease the area with panel wipe. This helps remove any silicone bits, dust mites etc causing the paint to react ewith the surface
- Then prime using relevant primer (not filler primer). You may wish to heat the panel slightly with a hair dryer (avoid direct heat) - just to warm the panel - this will help with trhe curing of the paint - especially if the garage is v cold. Dont get the panel v hot - just warm to the touch.
- For a pro finish, when the primer is fully dry, dust lightly with a speckle coat of black paint (spray far away and dust the area so its covered in little spots). This is called a speckle coat and when you sand back using dry 800+ wet n dry (dry) the indentented areas wont go as fast until you get down to their level. Once all dots have gone your area is level. Try and use a sanding block and keep your sanding paper clear of particles by tapping it clear regularly (use a compressor to blow it clean).
- Now - you may wish to reprime the area - and then smooth using 800 again. To "feel" the surface, place a cloth (j cloth) between your hand and the surface. If it feels rough then continue sanding.
- Once your happy, degrease the area again with panel wipe. This helps remove any silicone bits, dust mites etc causing the paint to react ewith the surface
- prepare your paint (either can or spray gun) - if using a can, submerse the can (minus spray cap) into a hot but not boiling tub of water to loosen up the paint. This makes it more fluid and it wont splatter. Fully dry the can before spraying - give it a good shake also as per can instructions
Then tack cloth the area just before spraying. This removes any last minute dust mites.
- Then spray - 1 even coat - start at the top and work down in horizontal strokes - overlap bottom or last spray line with top of new one.
Allow to flash dry (see can for time). This allows the solvent to evaporate before the next coat - also known as tack drying. Dont spray before this time otherwise solvent gets trapped in the previous layer and will react (ir goes milky, splits, cracks, doesnt dry etc)
- then apply another coat - do this at least 3 times
- Once fully cured (heat lamp about 7 hours - normal warmish garage about a week), smooth any specks with relevant wet n dry (1500 - use wet) - go easy though and watch edges/corners etc. If you have runs, flat right back and respray again fully.
- now if you dont intent to use lacquer you can buff up now (depending on size of area, a mixture of G4 compound and t cut is good with a polishing mop and or damp cloth) - or I find T cut and super resin polish is good for small areas. Just go easy and keep checking the area. Remember t cut softens paint and takes a fine layer off. Do it too much too hard and you'll get patch paint down to primer!
- If you intend to lacquer smooth off any nibs/dust specs etc, using 1500 wet n dry (wet), fully dry and panel wipe area. Dont worry about any matted areas - the lacquer will turn them into smooth shiney bits - just make sure you cant see any sanding lines. repeat the spraying technique - especially the tack cloth bit. The more layers you apply the better the protection and deeper the shine. Lacquer is the invisible layer that stops your paint from scratching, oxidising. When you t cut paint, you t cut a layer of lacquer. the more you apply, the longer and thicker the protection. Just go easy - its very thin and can run easily.
(for reference, lacquer is where pearl paints, glitter paints and other fancy paints are usually embedded onto a cars paint work - mixed in with the lacquer).
- Remember, depending on the area you may want to check for a colour match as paint around it may have faded (noticeable on red cars). Pros will respray the whole panel/side to mask this.
Also - I'd avoid using hammerite as an undercoat to protect areas if you intend to paint over it. Hammerite is an enamel based paint which reacts badly with some cellulose/2pak/acrylic based paint systems. It can bubble and crack when it reacts. Not what you want with a rust prone area.
If youre treating an area like a joint (ie in the engine bay seams or arch lip) make sure any seam sealer hasnt perished. If it has remove fully and treat again using red stripe or similar sealer. DON NOT USE SILICONE BASED PRODUCTS - these react with paint and cause annoying "fish eyes" - areas where paint wont stick.
Hope this helps
Ade
8)