How to - Repair and respray a front bumper

[Keyser]

I have seen several discussion on guides and also lots of "How much to re-spray my bumper" and How to repair my damaged bumper threads.

With this in mind I'm gonna try and write up this little job as a guide,

(if the Mods and members in general think it's not worth keeping in guides please move I won't take offence )

 

I do appreciate that I have the unfair advantage of having a well equipped ZedShed (garage) and hobby level spray equipment, however you could do a lot of this yourself and the prep is labour intensive so if you get it even just ready for primer your onto a winner (it's not hard as my apprentice will demonstrate if he can you can)

 

So the first thing we need is a damaged bumper BOB? Drive over that speed bump!

Thanks!

He's always happy to oblige

 

Firstly strip all the bits off - reflectors number plate, grill, canards and anything else Bob has no badges but there are guides on how to remove them.

 

 

Next access the damage remove loose and cracked shards of paint and fibreglass, it's better to replace than try and stick it back down with filler of a thin coat of resin (in my experience)

 

Bob has 3 split in his and where they end right on the edge of the bumper you need to reinforce or it will flex and just crack away.

So I ground out the end of the split to make it deep enough to repair properly

 

 

Next clean and sand the inside face where the reinforcing and patching will take place I used a 180 grit sanding disk attachment on an angle grinder (Lightly!!!) it can be done by hand or with a drill attachment.

 

 

sand off the loose and split material behind any splits or cracks

 

 

 

Next step is the fibreglass, Available in kits from Motor factors or eBay or as individual packs of resin and hardener and the matting.

 

Pre cut several patches from the matting and lay near to where they will be needed

 

Then simply mix the resin and hardener as per the instructions on the tin

 

TOP TIPS

1. Most people use to much hardener so it goes off to quick try not too

2. Mix in small quantities it will go off before you finish otherwise so make 2 or 3 small mixes

3. Use old plastic pots (margarine yoghurt etc) and bin them when finished along with a cheap brush

4. Wear latex gloves, save hours of scrubbing

 

Paint the resin onto the area to be repaired then lay the matting on top (you can dip the matting into the mix but it can be hard to use as it will fall apart) paint generous amounts of resin on top. the aim is to fully impregnate the matting and remove ALL air from in or under the patch.

 

Build up in layers until you are happy. Don't worry about neatness at this point it is easier to sand back to an edge than try and line up the matting perfectly

 

work the corners to get the matting all the way in and remove the air

 

 

Again building in layers

 

 

if it needs to be built up more wait for it to dry and add more - this is a bridge on the end of a split

 

 

Then sand back the excess with a course grade paper, I'm using 240 grit paper on the angle grinder but it's easy to go too far with that sort of cutting power!

 

 

Then go over it with something a bit less aggressive I'm onto a 320 now

 

 

Then to the filler, again plenty to choose from I use an "easy sand" option.

Filler is an art (that I don't have) so the same as the fibreglass mix in small portions and build it up - I'm told lots of thin layers is better than one big thick layer anyway,

 

 

Then sand it down, again working through the paper grades we started at a 120 to get the rough shape and very quickly down to a 400

Apprentice shot

 

 

 

Now sand it again - a block is useful - I'll get a picture for the next post

Second coat of filler and more sanding

 

 

TOP TIP

Run you finger over the repair - if you can feel a bump or a dip or a little dimple - you will see it in the paint!! You can feel the imperfections better than you can see them at this point!

 

OK looking good? - SAND IT AGAIN!

AND AGAIN

OK Then it should now feel smooth and be looking something like this

 

Now another decision what are you doing? A full re-spray or a blend?

This one is a full re-spray so now the whole front bumper gets the 400 treatment, work the whole area and don't miss the awkward corners, when you think you have it just right - SAND IT AGAIN

FYI we are dry sanding at the moment, we will switch to wet and dry for the final sand before paint.

 

So that gets us to here -

 

 

We will finish the prep and get ready for primer this week so the next stage will follow soon.

 

 

Standard Disclaimer -

1. Don't follow this guide!

2. I am untrained, unqualified and have no idea what I'm talking about.

3. If you follow this guide and damage your car in anyway refer to disclaimer line 1

 

P.S - Sand it again

Edited December 3, 2012 by Keyser

[The Bounty Bar Kid]

Top info from the ZedShed as always! Cheers dude!

[ThriftyFifty]

What spray gun you use Chris?

 

p.s. I know we're not at that stage yet

Edited November 25, 2012 by ThriftyFifty

[Zed devil]

Great guide, well done ðŸ‘

[DoogyRev]

Great Guide Chris

[jumping350]

excellent guide chris im still doing my rear bumper been blending and sanding that b**** for months!!i am doing it on my own and waiting for tips from my looooong mate!! this will hopefully speed up the process thanks

eagerly awaiting the next stage ...i knew i should of just driven it down to you months ago

[Kev T]

Great guide well done.

[Ricey]

Excellent guide mate........also your full of @*!# with this whole 'I don't know what I'm doing business' !!!

[Keyser]

You had to ask didn't you!

 

OK to be fair I have a collection - most are in the £20 - £60 range LVLP style I have a gravity feed gun for heavy primer

 

 

But in the middle is my new toy a Devilbiss FLG-5 it is the bottom end or there line but you can pay £500 for a high end gun

 

This job will be its first run but if it is even close to the one I tried it will be a pleasure to use

 

Love air tools

[Keyser]

Excellent guide mate........also your full of @*!# with this whole 'I don't know what I'm doing business' !!!

 

That's just the disclamer in this sue anybody for anything world we now live in you gotta cover ya backside

[RobPhoboS]

Excellent stuff.

 

Whilst on this subject, has anyone tried this wipe-on method as mentioned here:

http://www.detailingworld.co.uk/forum/showthread.php?t=217520

 

?

[Flex]

Once again Chris is winning!

[350Chris]

Ahh, the joys!!

 

Best thing about bodywork is the technicolour bogeys!

[Keyser]

Part 2 (The Return)

 

So after sanding down with a block

 

 

or if you're a flash/lazy git an air powered DA

 

 

We can see some bits that need more filler

 

Mix a drop of filler - this in on the knife so it's not much

Mixed

 

Then build it up

 

 

Let it dry and sand again

 

 

Repeat until smooth

 

When happy with the filler, its time to prep for paint, the zigzag marks here

 

 

are from using a coarse grit (P120) to rip down the fibre glass repairs - they can show through to top coat so they have to go - 240 - 320 - 400 sanding and we have

 

 

no zigzags

 

I needed to recreate a half round feature line in the bumper that had been filtered over - I simply found a screwdriver with the right sized shank wrapped the sand paper round it and working my way down the grades recreated the dip

 

 

Onto stone chips

 

The ones that show through white are exactly that chips or holes in the paint all the way down to the base coat - if you don't remove them the will show up in the top coat especially if you're using rattle cans as they don't lay the paint on very thick.

 

The next 2 shots give you an idea of how much you need to remove to get these little beggars smoothed out

 

 

 

 

 

due to the number of chip[s and blemishes in this bumper I'm switching to a high build primer to try and help get a smooth finish.

 

Onto Primer

 

I'm using a 2K High Build Primer - This stuff is not nice don't mess with it without the correct gear!!

 

I used cellulose paint on my Zed and went through a few fly masks

 

 

That is the minimum protection for spraying you can apparently get these that are 2K rated but opinions vary the best thing is one of these

 

 

An air fed mask, Why, because they are the safest and you can pretend you're a character in Halo when your all suited up

 

That and a pair of latex gloves (SMD gains interest ) and your good to go simply hook the mask up to your spare compressor

 

 

which is outside collecting lovely clean air

 

(yes I have a stupid amount of equipment)

 

Primer prep

Get everything ready

Then you need some heat especially in this weather!

I use this to really bring up the temp

 

 

But gas heaters produce water so I never have it on when spraying and use this

 

 

to keep the shed warm when spraying - 3KW electric)

 

Next secure you piece in place so you can get to all of it

 

 

Then clean it with either tack rags or I like panel degreaser

 

 

Mix your paint

 

 

These are great the mix for this primer is 4:1 Primer and Hardener and I'm using 10% thinner as high build is thick and I'm using a 1.6 nozzle on the gun

I used 260ml Primer, 65ml Hardener and 35ml of fast thinner giving a total of 360ml of primer about enough for 2 good coats.

 

And apply

 

I can't really teach anyone how to spray there are plenty of vids around and information on technique but so much affects it, what paint, the gun, air pressure ambient temperature etc etc.

The best way to learn is to do it I'm OK at it I can get a reasonable finish and I have a DA polisher for the rest

 

The good news is this is primer and even if you get it quite badly wrong it doesn't matter as you're going to flat it all down again anyway a bad job to us just means more time sanding

 

So to prove the point the first thing I did was make a mistake

 

I walked up to the bumper swung the gun up and a drip of paint, that I have no idea where it came from landed straight on the bumper but I just carried on I'll get it with the flat back.

 

 

So after 2 coats the bumper is now here

 

 

 

Next instalment will be prep and colour coat

[The Bounty Bar Kid]

Nice work dude!

[Keyser]

Part 3 - Revenge of the lacquer!

 

So we start today with a bucket of warm soapy water - helps keep the wet and dry from clogging up

 

I also had a photographer Buster (don't you just hate it when your being watched )

 

So 800 wet and dry all over the first bit was my now dry drip

 

 

any tiny blemishes can be sorted with "stopper" a very fine filler

 

Then onto paint

 

 

Mixed and ready to go

 

starting with the awkward bits

 

 

Then a "mist" coat

 

 

and build up the paint

 

 

Finished base coat

 

 

Next up the clear coat after about 20 mins

 

 

Good shot of the mist you don't want to be inhaling

 

 

Getting a shine

 

 

 

The finished bumper

 

Before

 

 

after

 

 

Of course just to show how badly you can balls it up and still put it right I deliberately put a couple of runs in

 

 

So I'll be showing how to sort them when it's dry enough for polishing - about 48 Hours

 

I will leave you with this

 

 

That's the reflection in the newly painted bumper - not bad, not bad at all

[buster]

awesome work today m8.cant wait for the next stage

[Beb]

Woohooo you got an air fed mask, finally given in to the 2k... slightly safer than my "I'll hold my breath" technique

[Keyser]

Last bit

 

So after the lacquer (or clear coat) is well and truly dry (mine is rated at 48 Hours) we can polish it

starting with the run I deliberately (O yer ) put in

 

 

I started with a 1200 in my DA very carefully and with lots of water - be very careful the same as polishing edges and corners will rip down to primer in seconds!

so stopping and checking often

 

 

the aim is to remove all the "orange peel" the thicker swirls are the run slowly coming down.

over to a 2000 grit and by had we want a flat dull surface all over

 

 

This is not easy to photo with my cheapo camera in artificial light but you get the idea keep going until its all that dull look,

 

Then out with some more toys

 

 

rotary polisher and some aggressive compound

 

 

then onto

 

 

a DA and something a bit less aggressive again the same applies especially with the rotary watch the edges!!

 

When it's finished it should be like glass - mine came out like this (best pic I could get)

 

 

and the finished article

 

 

hope it helps someone - good luck with it

 

 

The End.

[theheff]

awesome mate.

[The Bounty Bar Kid]

Well done and I'm sure others will agree with me when I say on behalf of the forum, Thanx! Really useful dude!

[glrnet]

as usual, but I do agree with Ricey

[jumping350]

epic :notworthy: :notworthy: seriously impressed with that and very useful for us novices...im quite a few steps behind that but at least now i know how far along i am and need to get to...maybe a sticky???