Everyone at one point in time gets their bumper kicked, chipped, scratched etc....
and no one wants to fork up all the money to get the bumper painted (unless ur really picky and got mulah comming outta ur crackhole)

as for everyone else this is how to sand down a bumper that has been scratched (medium to deep cut but not cut thru).

step one.
Clean Bumper with a type of PREWASH (a very light thinner that will not cut thru the paint but good enough to remove all grease dirt etc.) if u dont have a PREWASH solvent use rubbing alcohol.


step two.
Using a orbital sander use a 240 grit sandpaper and start sanding. (remember 240 is a pretty strong grit use this only if u want to remove the paint on the bumper)

SIDE STEP.
If u were planning on fixing the bumper because of a small damage that leaves a mark use 80 grit but make shure u cover the surrounding area aswell this way the entire area is balanced out and not weavy afterwards but dont sand the entire bumper down with 80 grit.

(after doing this and the mark still remains use polyurathane liquid filler and fill it in and then sand down again. If its a really small hole or scratch fill it in wit PUTTY)

SIDE STEP.
If ur planning on fixing an imprint that has left NO mark all u have to do is get a heater gun and from the front of the bumper heat the imprinted area and surrounding and then use a baseball or even a type of roller and from the back side of it push out the imprinted area and eventually it will. NO SANDING IS REQUIRED unless u want to refinish in that event continue the other step.

step three.
Use 400 grit to finish the bumper preping portionso all the roughness from the 240 grit smoothes down. Make shure u get all the edges etc properly.

step four.
Prime the bumper with primer make shure u get all the damaged areas well because if there are still light sratches remaining the primer will fill it.

step five
after the primer is dry use 400 grit paper to sand down the bumper (not too much just to give it a smooth touch)

step six
time to WATER SAND use 600 grit WET sand paper and soak it in water and then start sanding the bumper completely but only a thin layer

step seven
wash the bumper wit water and then use PREWASH or rubbing alcohol and then clean the bumper off.

step eight
if ur at step six and u notice there still is some tiny holes or scratches still appearing then fill it with putty filler. and then re sand.

step nine
Ur ready to paint the bumper this i wont tell u how to do cuz i dont want u to screw it up so u can take it pretty much to any shop and let them paint it this way all they have to do is paint it and no charge applies for all the labour that would normally appear.

MODS feel free to make this a sticky.

 

when painting/priming make sure all other parts of the car are covered, this will eliminate the affects of overspray

 

i think i forgot to mention it but this method is only if u had ur bumper off cuz alot of this stuff is pretty intensive work.

 

how much money approx. do you think you would save prepping your bumpers and such before paint?

 

Good write up, I like it.

 

put it this way basically to do a whole bumper refinish its about 4-5hrs if done properly.
thats everything from wash to paint.

if u do this work all ur self all the painter has to do is when u give it to them just straight paint and clear which is 1 hr so u save over 3 hrs. plus to top it off u have self satisfaction.
ontop of that u save lots of money
for exacmple if it was 200 bucks to refinish the bumper now all u have to do is pay for the paint and 1 hr labour.

 

Nice writeup.
Make it a sticky!

 

does this process apply for the whole car?

 

nope

just for bumpers, lips, mostly urathane stuff not metal etc..

 

ok...next do a write up on prepping the rest of the car :P

 

no problemo

 

ok, lets say we take the bumper down to the urethane, or its brand new. What primer should we use that will properly adhear to the urethane. I heard you have to take a chunk of the eurethane and see if it floats or not cuz theres a few diff types... not sure if thats tru or not...

 

Considering I painted a lip for my friend with regular tremclad paint, I don't see what regular primer wouldn't work?

 

yah regular primer is cool
use 2:1 primer .

 

what happens if u dont get it paint with basic and clear any different with sanding
Thanks
Pierre

 

u mean if the bumper isnt painted and u want to get it ready to paint???

if thats the case u dont have to sand the bumper all u have to do is get a scuff pad and scuff it up. make shure there aint any deep scratches etc if there are sand them down and then primer that surrounding area only.

 

ok i dont mean to crap this thread but please do not wetsand before painting

step 1 - sand down damaged are with 40-80

step 2 - apply any bondo at this point

step 3 - sand down bond and shape with 40-80 grit then take down with 120 and prime afterwards

step 4 - sand primer with 180 then 220 then 320 then 400 all with priming in between if any polyester filler is used for small scratches.

step 5 - prime entire area to be painted and sand down with 400

step 6 - paint in dry coats DO NOT apply paint as to where it gives off a glossy shine

step 7 - clear coat and remember to keep the edge wet with clear coat

step 8 - now if you wish to water sand get some 1200 or finer and sand the clear coat DO NOT burn through to the color. only sand until the surface has a dusty look to it

step 9 - now get out your buffing compounds and cut the clear to a shine with your buffer

important notes:

- never sand by hand, buy blocks, borrow blocks steal blocks just do not think that your hand is square and use it what so ever. they make flexable foam blocks if your doing a round area

- use the biggest sanding block you can on the area, or you will never get it straight

- when sanding bondo cross hatch cut the bondo on a diagonal making X cuts to ensure a straight and even surface

- if you use polyester or putty allow it time to shrink before painting, as the chemicals in it that allow it to be workeable evaporate when it hardens and the putty will shrink

 

hey bro where did u learn to do this stuff? not to bitch at ur input or anything but i work at FORMULA HONDA BODYSHOP.
we have the industries best everything. i am pretty shure i might know a thing or two.

and oh yea u have to wet sand before painting. or u will never get a smooth finish. stuff like that is what back alley shops do to save money and time. if u want profesional results u should always wet sand. and oh yea u dont use bondo to fix bumpers what kinda **** is that??? use panel bonding etc... by 3m.

 

I was talking about in general repairs, you never wet sand before painting man the paint needs a somewhat porse surface to adhere properlly to, ohh and by the way I learnt at The Guild Of Automotive restorers a WORLD renowned restoration shop, yeah for a plastic bumper you dont use bondo, I was talking in general for repairs as the 3m panel bond would require the same steps. And for the first cut your gonna wanna use something like 120 then cut the 120 scrathec out with a 240 then if you want a smooth finish cut it with 320 then cut out the 320 scrathes with 400.

http://www.theguildofautomotiverestorers.com/

There is the website to the shop I worked at, check it out if ya want.

 

u have to wet sand before painting bro.
and yes the paint will stick on. it all depends on how u blend ur paint wit the hardener n ****. it has nothign to do with the watersanding.