Looking for advice on repainting a frame

Jim Lyon

Hi,
My 21+ year old Trek 820 is getting to the stage where the frame needs repainting, & my finances dictate that I do it myself, so I'm looking for some advice.
I've been running the bike with a complete rear mud guard to protect the front mech. & because front mudguards don't last for too long in the dirt I've been running a "crud catcher" on the front down tube ( & most likely why I'm also looking for a new set of steering head bearings - see other post ). As a result, the places where the paint has deteriorated most is around the bottom bracket & underneath the front forks, above the wheel.. In other areas there are small sections where paint has been
chipped off by gravel or small stones, etc.
While the original paint isn't in a great condition where it's been damaged, it isn't really so bad that I feel inclined to completely strip all of it back to bare metal. Rather than that, I'd prefer to use a drill with a wire brush attached, not only to remove rust, but also any paint that isn't strongly attached Next cover the bare metal with "rust converter" In these areas, I'll initially build up the level by using a thicker brush applied primer. When that's achieved, I'll rub down the whole frame in order not only to level off the different areas, but also key in the other area for a grey aerosol primer. This is not only because it's easily applied, but as I don't know what type of paint Trek originally used, I wish to use that primer to separate the original & final layers in order to prevent any unwanted chemical reactions.
So, I'm looking for a strong, hard wearing externally used paint such as Dulux or similar that's got good "chip resistance". Ideally in a single/plain colour as near to a peppermint green as possible. I thought I'd put on a couple of layers by hand brush & when they've hardened off, rub them flat with a lighter grade of wet & dry, then a thinner top coat applied by a Lidl's compressor powered air brush,
After that I'd like to fit a locally purchased set of graphics copyimg the oiginal, just so as the overall effect isn't too bland, & while it seems logical to coat them & the frame with a couple of coats of clear varnish/lacquer to finish off. Trouble is though I've come across the occasional varnish/lacquer in a "rattle can", to be honest I don't have much idea of what brand or type to go for so any suggestions as to whether or not to give a final coat or two of clear coat/varnish or not? Where best to obtain them from & indeed any criticisms, hints or suggestions would be appreciated. And amounts of paint /lacquer to initially buy would help.

Cheers,
Jim

Monty Dog

It's probably be cheaper and a lot less hassle to get a single-colour powder coat

dgunthor

Monty Dog wrote:

It's probably be cheaper and a lot less hassle to get a single-colour powder coat

yup, i'd get it sandblasted and powdercoated

Peanut651

I'm a spray painter, just recently painted my Dr Jekyll. I can tell you this, do not do it with a brush lol.

The only real way to strip paint off the frame is to sand it or paint stripper that won't affect the metal below. A wire brush on a drill will only score the metal and give a horrible finish if you don;t fill in the scratches. Also, using different paints like you're planning, you will only get reactions (cracking, bubbling etc) and you'll have to strip ALL the paint and start over again. If you were to do it your self use aerosol car paint, it's the most durable on a tight budget.

Preparation is the biggest factor when it comes to a good finish. Everything has to be super smooth because paint doesn't fill scratches or chips, it just shows them even worse when finished.

Unless you are very good with a spray tin your best bet is to strip the whole frame down to bare metal and pay someone to powder coat it. A crap finish with paint can make things look worse than when you started.

I painted mine at work with proper paint and hard wearing lacquer, but I do this kind of stuff everyday and I still find it a PITA doing bikes.

20150417_140742[1] by Peanut651, on Flickr

Jim Lyon

dgunthor wrote:

Monty Dog wrote:

It's probably be cheaper and a lot less hassle to get a single-colour powder coat

yup, i'd get it sandblasted and powder coated

OK, convince me, what kind of money are we talking about?

The Rookie

I wouldn't powdercoat steel personally, if moisture gets in under the coating you can get quite a lot of rust before it breaks out, much prefer paint.

You could rub down (not wire brush, you'll never fill the scratches), but personally I'd chemically strip or get it soda blasted (much better job than sand blasting).

dgunthor

Jim Lyon wrote:

dgunthor wrote:

Monty Dog wrote:

It's probably be cheaper and a lot less hassle to get a single-colour powder coat

yup, i'd get it sandblasted and powder coated

OK, convince me, what kind of money are we talking about?

depends on the powdercoaters, but £25 to £50

Jim Lyon

Post by Peanut651 » Wed Apr 29, 2015 6:43 am

Hi,
Thanks for that ( & everybody else who made an input ), your enthusiasm is much appreciated.
Before I get into directly replying to your post, I've been trawling round google & now feel the need to find answers to the questions that's raised. - So I hope you'll bear with me?
Previously I've done some spraying with "rattle cans" & had reasonable results but didn't do it often enough to get consistently good e.g. after ages away, I'd spend too long regaining sufficient hand -eye"co-ordination. basically I need much more practice to get good @ it.
From what I've just read on the internet, 2K /2 Pack/Acrylic paint seems very attractie e.g. large choice of personally customised packs ( etch primer/paint/lacquer ) ; very hard chip resistant finish, etc. However, the "fly in the ointment" is
the hardener contains ISOCYANATE which can be lethal. On this link, scroll down until you get to "2K"

http://uk-mkivs.net/topic/65765-how-to-spray-paint/

Granted that some of that might be over reactive "urban myth" that, being 4 years old might be out of date ( after all,
the reason that "modern" paint stripper is less effective is because the H&SE had various toxic chemicals removed. For all I know, they might have recently had isocyanate removed from 2K & while this is a problem that the general public seem largely unaware of. checking the relevant part of the H&SE website

http://www.hse.gov.uk/coshh/industry/mvr.htm

it appears they recognise it as a CURRENT it problem, though it seems somewhat downplayed compared to
other people's reactions. But the important bit seems to be they recommend minimum safety equipment.
So, while their appears to be a gap between the two positions, it would appear that if people screw up, there are NO second chances !
Given that, & the fact I'm only likely to be doing occasional one offs, it makes more economic sense to pay others who have the equipment I can't afford. - Which would appear to put 2K Acrylic painting & powder coating on a similar level in that I would need to pay someone else to do it. But bear in mind although I'm thinking of one colour only,( 2peppermint green" appeals to me ) I am interested in some graphics & a lacquer coat over that ( & 2K lacquer would appear to give the necessary toughness to protect the graphics - but whether 2K lacquer is compatible with powder coating, I'e yet to find out? ) and whichever of those two roads I go down, does anybody have a rough idea of the cost of powder coat/ 2K Acrylic with lacquered graphics? - BTW, I live in North East Sheffield, so if anybody can recommend a good powder coater / painter
( preferably with the gear to do it all "in house" e.g. sand blasting, etc. ) in my area hat would be a great help.
As for doing it all myself as that still needs finalising, I'll return to replying to this post.

I'm a spray painter, just recently painted my Dr Jekyll. I can tell you this, do not do it with a brush lol.

JL - One tip I learned which works with even cheap brushes is to "run them in". What you do is take a new one to the corner of a brick building & just keep flicking the tip of the brush back & forth against the corner to soften up the tips of the brush, so it doesn't leave stripes in the paint. Usually I find that with two coats with a "run in" will give me a reasonable finish with two thicker coats of e.g. Dulux. . Flat that down a thinned down coat of air brushed DULUX top coat should do, especially if I can find a strong (2K Acrylic ) lacquer to go over the graphics?

The only real way to strip paint off the frame is to sand it or paint stripper that won't affect the metal below. A wire
brush on a drill will only score the metal and give a horrible finish

JL - Fair point. I only brought it up as a means of making sure that the paint around the edges of damaged area was still strongly adhering to the frame. - So, how about using a wire drill brush with brass wire & going easier on the pressure
applied?

if you don;t fill in the scratches. Also, using different
paints like you're planning, you will only get reactions (cracking, bubbling etc)

JL - In more detail, I was thinking of using the type of "brush on" red primer that no longer uses lead, & leave some to thicken up slightly before applying, then using several coats to build up, then leave to harden off before rubbing down. After rubbing it all down, I was thinking of using a "rattle can"" grey primer to act as a barrier between the two different layers of paint i.e. original
& e.g. Dulux.

and you'll have to strip ALL the paint and
start over again. If you were to do it your self use aerosol car paint,

JL - By that do you mean cellulose or 2K Acrylic? - Which do you prefer & why?

it's the most durable on a tight budget.

JL - It is getting slowly better but I still have to be carefull.

Preparation is the biggest factor when it comes to a good finish. Everything has to be super smooth because paint
doesn't fill scratches or chips, it just shows them even worse when finished.

Unless you are very good with a spray tin your best bet is to strip the whole frame down to bare metal and pay someone t
to powder coat it. A crap finish with paint can make things look worse than when you started.

I painted mine at work with proper paint and hard wearing lacquer,

JL - Did you use cellulose or 2K Acrylic?

but I do this kind of stuff everyday and I still find it
a PITA doing bikes.

JL - Look upon it as being character building! : )

The Rookie

2 pack paint is better but must be applied by a professional in a booth for the reasons give, Cellulose is what you can by in cans from various outlets. With care a good finish can be achieved using 'rattle cans', much better than brush, so why bother with something that will be harder to achieve a good finish with?

You haven't yet said if the frame is alloy or steel, this effects a number of answers to your questions.

jimothy78

I tried repainting with rattle cans last year with my old Hardrock frame. The stripping was a real b*tch, and I did resort to a small rotary wire brush in some of the fiddly places.

The boys who warned against this above are right - you will get little scratches that show through (you can see some at the very top edge of this picture:

Not too bothered by this - after all, a mountain bike is gonna get scratched and chipped anyway.

Another (more important) word of warning - when you're choosing your paint colour/s - check the appearance WITH LACQUER ON TOP. In my case, the nice bronzy, metallic colour I thought I had chosen was utterly transformed by the addition of the lacquer into something like a much richer, chocolate brown, which was not what I was after.

The Rookie

Does that mean it looks like 5h1t?

I picked a colour based on what it looked like on cars I'd seen driving round!

If it's an alloy frame you must use an etch (acid) primer, the normal stuff won't cut it.

jimothy78

The Rookie wrote:

Does that mean it looks like 5h1t?

That comparison has been made, yes

I picked a colour based on what it looked like on cars I'd seen driving round!

Yeah, I tried to do the same thing, but couldn't find a rattle-can for the car/colour I spotted, so ended up choosing one off the shelf that seemed pretty close :oops:

If it's an alloy frame you must use an etch (acid) primer, the normal stuff won't cut it.

Yep - got etch primer from Halfords - worked nicely - very good/even coverage and bonded well.

The Rookie

Halfords didn't do it when I did mine, but the can I did buy (from a paint specialist) is from the same manufacturer, and yes it's good stuff.

Jim Lyon

Thanks guys Keep it coming !

To explain a little further, my experience is not only limited & out of date ( I've only very recently heard of 2K Acrylic ), but I'm also going up a level!
The frame is steel.

The Rookiie
<SNIPPED>
but personally I'd chemically strip or get it soda blasted (much better job than sand blasting).

JL - That's a point I was going to bring up, as I'm a bit concerned that sand blasting could be a little brutal
( especially if the operator gets a little too "enthusiastic"? ) - Is soda blasting not only more sensitive but also generally readily available ( if not, any recommended alternatives? )
I must admit I'm leaning towards 2K Acrylic in a single colour with graphics & 2K lacquer to top off. - Presumably I'll have to get the graphics separate? Any idea of typical costs? Then get a painter to soda ? blast, paint, fit graphics & lacquer? - Any idea of the likely cost of that part?
If I'd thought ahead, I'd have put a set of worn out bottom bracket race caps/ends to one side for this, so
will have to use the existing ones ! ?
For the processes discusssed is black or silver bodge tape sufficient ( & how many layers? ) to protect the bike's "delicate parts"

The Rookie

As its steel you can sand blast, but Soda blasting is now readily available, it uses the same equipment, and less likely to cause an issues.

Again as it's steel, personally I'd paint not powder coat you can go with a pro respray, phone around as long as you mask up you can probably get a local bodyshop to fit it in quite cheap, but as I said if you are careful and patient you can get a very good result using tins, but it does take care and patience, it will save you some money, you'll have some paint for touchups left over, and you may not want to cry as much if it gets scratched first time out!

Jim Lyon

The Rookie wrote:

As its steel you can sand blast, but Soda blasting is now readily available, it uses the same equipment, and less likely to cause an issues.

Again as it's steel, personally I'd paint not powder coat you can go with a pro respray, phone around

JL - When I'm finished here I'll probably hit Sheffield Forum to try & get some feedback as to who does a good job, etc

as long as you mask up you can probably get a local bodyshop to fit it in quite cheap,

JL - I'd appreciate it if you could give me a top to bottom price range, just somewhere in the ball park to give me a rough idea would be a great help/

but as I said if you are careful and patient you can get a very good result using tins, but it does take care and patience,

JL - If the job isn't too pricey I'll go for it as I've also got a LOT of time pressure.

it will save you some money, you'll have some paint for touchups left over, and you may not want to cry as much if it gets scratched first time out!

JL - That's another point I was going to bring up, with 2K Acrylic, is there any way of getting round touch up? Is 2K Acrylic inert to other paints? Or might I need e.g. some kind of barrier between the 2K & using a similar coloured cellulose to cover any damaged areas?

The Rookie

If you can find a bodyshop that will fit it in, you could get it done for circa £15-20 upwards, cheaper still if they already have the colour you want sitting around spare.

You can use cellulose touch up onto acrylic without issue, yes, one advantage of using a car colour is that it will be readily available, as it happens I went for Ford Metallic purple on mine, common on the older (square edged - upto 2008) Fiesta as I liked it and I new paint to keep it could would be readily available.

Jim Lyon

Thanks for the pointer that cellulose can be used over acrylic. - While aluminium frames require etch primer, can I assume that steel frames only require"ordinary" primer? - Any additional comment(s)/advice?

The Rookie

Yup, regular primer on a steel frame.

Peanut651

Jim Lyon wrote:

Post by Peanut651 » Wed Apr 29, 2015 6:43 am

Hi,
Thanks for that ( & everybody else who made an input ), your enthusiasm is much appreciated.
Before I get into directly replying to your post, I've been trawling round google & now feel the need to find answers to the questions that's raised. - So I hope you'll bear with me?
Previously I've done some spraying with "rattle cans" & had reasonable results but didn't do it often enough to get consistently good e.g. after ages away, I'd spend too long regaining sufficient hand -eye"co-ordination. basically I need much more practice to get good @ it.
From what I've just read on the internet, 2K /2 Pack/Acrylic paint seems very attractie e.g. large choice of personally customised packs ( etch primer/paint/lacquer ) ; very hard chip resistant finish, etc. However, the "fly in the ointment" is
the hardener contains ISOCYANATE which can be lethal. On this link, scroll down until you get to "2K"

http://uk-mkivs.net/topic/65765-how-to-spray-paint/

Granted that some of that might be over reactive "urban myth" that, being 4 years old might be out of date ( after all,
the reason that "modern" paint stripper is less effective is because the H&SE had various toxic chemicals removed. For all I know, they might have recently had isocyanate removed from 2K & while this is a problem that the general public seem largely unaware of. checking the relevant part of the H&SE website

http://www.hse.gov.uk/coshh/industry/mvr.htm

it appears they recognise it as a CURRENT it problem, though it seems somewhat downplayed compared to
other people's reactions. But the important bit seems to be they recommend minimum safety equipment.
So, while their appears to be a gap between the two positions, it would appear that if people screw up, there are NO second chances !
Given that, & the fact I'm only likely to be doing occasional one offs, it makes more economic sense to pay others who have the equipment I can't afford. - Which would appear to put 2K Acrylic painting & powder coating on a similar level in that I would need to pay someone else to do it. But bear in mind although I'm thinking of one colour only,( 2peppermint green" appeals to me ) I am interested in some graphics & a lacquer coat over that ( & 2K lacquer would appear to give the necessary toughness to protect the graphics - but whether 2K lacquer is compatible with powder coating, I'e yet to find out? ) and whichever of those two roads I go down, does anybody have a rough idea of the cost of powder coat/ 2K Acrylic with lacquered graphics? - BTW, I live in North East Sheffield, so if anybody can recommend a good powder coater / painter
( preferably with the gear to do it all "in house" e.g. sand blasting, etc. ) in my area hat would be a great help.
As for doing it all myself as that still needs finalising, I'll return to replying to this post.

I'm a spray painter, just recently painted my Dr Jekyll. I can tell you this, do not do it with a brush lol.

JL - One tip I learned which works with even cheap brushes is to "run them in". What you do is take a new one to the corner of a brick building & just keep ******* the tip of the brush back & forth against the corner to soften up the tips of the brush, so it doesn't leave stripes in the paint. Usually I find that with two coats with a "run in" will give me a reasonable finish with two thicker coats of e.g. Dulux. . Flat that down a thinned down coat of air brushed DULUX top coat should do, especially if I can find a strong (2K Acrylic ) lacquer to go over the graphics?

The only real way to strip paint off the frame is to sand it or paint stripper that won't affect the metal below. A wire
brush on a drill will only score the metal and give a horrible finish

JL - Fair point. I only brought it up as a means of making sure that the paint around the edges of damaged area was still strongly adhering to the frame. - So, how about using a wire drill brush with brass wire & going easier on the pressure
applied?

if you don;t fill in the scratches. Also, using different
paints like you're planning, you will only get reactions (cracking, bubbling etc)

JL - In more detail, I was thinking of using the type of "brush on" red primer that no longer uses lead, & leave some to thicken up slightly before applying, then using several coats to build up, then leave to harden off before rubbing down. After rubbing it all down, I was thinking of using a "rattle can"" grey primer to act as a barrier between the two different layers of paint i.e. original
& e.g. Dulux.

and you'll have to strip ALL the paint and
start over again. If you were to do it your self use aerosol car paint,

JL - By that do you mean cellulose or 2K Acrylic? - Which do you prefer & why?

it's the most durable on a tight budget.

JL - It is getting slowly better but I still have to be carefull.

Preparation is the biggest factor when it comes to a good finish. Everything has to be super smooth because paint
doesn't fill scratches or chips, it just shows them even worse when finished.

Unless you are very good with a spray tin your best bet is to strip the whole frame down to bare metal and pay someone t
to powder coat it. A crap finish with paint can make things look worse than when you started.

I painted mine at work with proper paint and hard wearing lacquer,

JL - Did you use cellulose or 2K Acrylic?

but I do this kind of stuff everyday and I still find it
a PITA doing bikes.

JL - Look upon it as being character building! : )

Sorry, forgot I posted on this thread.

Before I start answering your questions, 2K paint is used every day in bodyshops, including primer, lacquer and solid colours like on vans and some cars. The chemicals in the 2k paints are lethal, that's why you must wear proper PPE (personal protective equipment) when using them, like air fed mask, spray suit and also paint in a suitable environment like a spray booth which also has air circulation and special filters.

There's no avoiding the isocyanate because there is no alternative.

If you get it painted in 2k paint you don't need to lacquer over the top because the paint itself is a gloss finish and durable. All you have to do is prep and prime before the 2k is applied. That's why vans are normally painted in 2k, easy to paint and a cheaper option to metallic water base paint.



Bodyshops normally do a variety of "blasting" with different types of material depending what metal they are working with. If you head over to your local bodyshop they will suggest the best action to take for what they have and if you only want them to blast it, it will only take a few minutes and cost pennies.

Before applying any paint to bare metal a quick thin coat of etch primer should be used before a good coat of proper primer. This assures there will be good adhesion to the metal.

If you have small scratches in the frame you can either fill them in with filler or apply some high build primer. High build primer is a kind of filler paint, it's very thick and will require sanding afterwards but it gives a lovely smooth finish for the rest of the paint. If you apply high build primer you need to finish the sanding with P500 wet and dry minimum to assure there's no scratches in the primer. Even scratches from p320 paper will show in the finished paint. this is wet and dry paper i'm talking about. The grades for dry sanding is different but I work with wet paper.



For my own frame I:
Blasted it to bare metal
Etch primer
high build primer
Sand with P500 for smooth finish
BMW Topaz blue (left over from another job) water base
2K clear coat


I did say bike are a pain in the a$$, but I love complicated jobs to do.