So I decided to give it another crack, ( couple paint prep questions )

Hey guys so I have given it another crack.

I started of with removing the existing body filler and doing it all over again as the body filler was exposed to the winter elements for a bit and the Z got a bot rust in the repaired spots

Today I have re boged the dents and then given the worked areias a couple coats of undercoat.

Questions

Firsty the areias I did today came out well but after spraying the primer on then snading it with 320 I have noticed a few real slight wobbles/bumps, so off with the primer and its like the layers of stock base coat, under coat and paint are making these bumps even tho I have sanded out the layers a fair bit.

Will this be noticble once painted ?

Another question is I have prepped the areia around the stock antena which i have welded in boged up and painted with under coat, the actual cirlce is just visible under the bog so the bog is very thin around the out side of the antena hole but it was all smooth and flush. The problem is I could feel a slight bump and after removing the undercoat it apears there was a hole in the bog like 5mm outside the cirlce where the metal came up so its like the metal is a high spot but I didnt weld there so it wouldnt have got hot and warped ?

I know pics wont realy help but here are some anyway






Cheers for any help

 

Save yourself from a world of grief, mate. ANY imperfections that you can see or feel, WILL stand out like dogs balls, once you have applied the top coats(you CANNOT polish out this sort of problem).

Do it right the first time, and you will never have to do it again.

Anything that is visible with bog or undercoat will be magnified 10 fold with a gloss finish.

 

Thanks chilli I am just trying to figure out where I am going rong exactly.

Do I need to sand out the layers of paint more or spread the bog over the dented areia aswell as the sanded back layers of paint ect ?? as im not sure what exaclty im doing wrong

cheers

 

With the wobbles and bumps, are you sanding with a block or just by hand? because sanding without a block can get alot of uneven bumps you really need a block for it to be nice and fair.

With the antenna area weldingcould have warped the metal, not sure exactly what you mean but if the metal is slightly higher maybe you can bog further around the area and fair it into the rest of the body dpending how high it is, you can get a special paint or even just a different colour primer then rub back and see where you are high or low. hope this helps a bit

 

Thanks heaps, yes I am using a few different sizes of sanding blocks no hand sanding what so ever !

What if I give it a tap with a ball pein hammer and add bog as im not keen on altering the chasy in a way where it sticks out to cover a bump.

Thanks again

 

not sure why it would be bumpy and wavey, an indicator paint would help to see where to sand more or less though, i have found it to help anyway

How was the hole welded? also most bog when it cures will shrink so i dont know if that is the problem?

 

The hole was welded up by tag welding in a pice of plate, yes the bog dose shrink thats why I did it in 2 layers to fill it up then another layer to skim coat the top.

Will bog shrink anymore after it has set for say 6 hours ?
I think the tin states you can sand it on a 20 deg day after 15 minutes but I was leveing it for an hour or so.

Thanks again

 

Yeah i would say most likely the welding would have warped it a little bit , i would just put another layer of bog until its smooth will just have to bog a slightly bigger area around it.
Depends on the bog the quick setting stuff probs alright with but it will usually state when you can sand and work and a full cure time in which it can move a little bit

 

The weld usually ends up being the low area due to it shrinking as it cools, professionals will a hammer ,dolly and black magic to stretch the metal back .
Just make sure the patch is lower than the surrounding area and the paint is feathered at least 70mm.
The bog should be applied over metal not paint and a high build primer will help in smothing it out.
If you can feel the dent it will show up in top coats.

Wheres Painter?

 

thanks for that, so high build primer is that the same as spray putty or is there a difference ?

thanks again

 

hi fill primer as in a hs 3:1 primer is what you need. for big areas use a nice speed file, dont forget to guide coat as well.

2 to 3 coates of hi fill over any repair area should be fine, a spray putty is simmilar. if you can get any de beer stuff then get there 145 hs primer.

 

hey thanks for that, what do you mean by guide coat ? and is de beer a brand name ? sorry I am not very familiar with these products.
So spray putty is fine tp youse over the bog if i cant get any hi fill primer ?


Thanks again

 

Pretty sure spray putty needs to be applied over a primer and shouldn't be applied directly to bog where a high fill can.
A guide coat is a very light mist coat in a contrasting colour that you spray over the primer/ hi fill before sanding. You then sand this coat off, but it will stay in the low areas that require more filling.

 

:rofl:


Bog will still be shrinking in 6 MONTHS
although the movement will be so small you wont 'see' it

bog also expands/contracts at a differant rate to what body panel does so even a hot day can alter the look of a repaired area under an experts eye

 

Much n a muchness ......

Most primers will have 2 mixing rates on the directions, one rate will be for use as a hi-build primer and the other will be just as a primer, basicaly its the amount of thinners thats added.......

little thinner = hi-build primer
&
lots of thinners = primer.

spray putty is a high build but its not a primer, it builds up better than a high build primer but requires sanding and priming...... obviously panel shops dont want added work so they simplyfy the process by doing the 2 jobs in one.

 

Guide coat is a simple visual guide as to what your 'seeing' when sanding

once the primer is on its a simple case of misting a pressurepak of black paint over the entire area, this will make the primer look 'spotty' up close (like thousands of tiny fly poops).

Once you start sanding the black spots dissappear first ..... EXCEPT where there's a hollow or low area, the block cant reach down to the paint so you get an indication of the area being visually low before you 'feel' it.

want more ........

http://autofix.com.au/blog/how-to-respray-a-car-part-six-using-a-guide-coat

 

Yeah they can be taken to 'show' the issues......

get a 4lit of 'prep wash' ........
wipe down the area your having troubles with

The primer will gleam likes its almost top coat allowing you to 'see' what it will look like when its actually painted.....

take a pic


the prep wash will dry quickly so you'll only have a few minutes to do this


NB:
dont repeat the prep wash trick to many times, it can effect the primer .... 3-4 times max !
&
make sure you wipe well past the area your scrutineering so you can see the overall look rather than just the repaired spot

 

most of the issues your getting is basicaly inexperiance.....

and we're all guilty of it when learning the art of repairing / painting cars.



The most common issue is over sanding..... you think you have a high spot so keep sanding and digging away at the area when in actual fact it may well need MORE building...... getting to know what your seeing and feeling is what seperates the professional and diy bloke.... & it takes time to get that understanding and develope the 'feel'.



It takes time....... you'll get there

when in doubt, use the prep wash trick, you can do that to the bog layer before you hi-build it, once its in hi-build, and in primer coat.
For learning, its a good simple trick to 'see' what's happening better.

Kingy

 

As Kingy says, inexperience is your greatest enemy and goes hand in hand with impatience.
We all try to get it done as quickly as we can, only to discover that it isn't exactly right.
Don't rush it. Time spent in preparation is time saved at the end of the day(there's an old saying "Slowly, slowly, catchee Monkey".

You'll get it right, just take your time.:zlove::zlove:

 

Bugger off all that prep man and just crack out the spray guns YYEEHEAAAHHH