Bogging

[fccool59]

Having my rear quarter without a spec of paint on it is not going to last too long so I figured I best prime it.
Its been a while since I painted bare metal and may have the procedure a little mixed up.
I started of with giving the panel a quick rub with 80 and mainly a speed file, next I conditioned it with acid, I was a lttle unsure about its effects on the lead so I tried to dodge it but ended up going over it wich did show a lttle oxidization on the lead. I then quickly went over the lead with 120 to remove most of the oxidization.
after cleaning with damp rags and drying I wiped all with prepsol and had a smoke then gathered up the stuff to start bogging.
about 40 mins later I started with a thin layer in the more needy areas, The bog is micro lite and was bought on clearance from my paint supplier.
The bog sanded very easy with very little clogging and seemed well.
I then noticed as it got thin that the bog was breaking of very easily and didnt take much to crumble, kind of seems like plaster filler for your house and it seems worse in the areas over lead were you can push it of with your finger.
, I have now done 5 applications and dont want to start again but I am worried about this being to weak.
any ideas of were the problem is?

[Dave_EH]

Leon,

I always undercoat in primer and give it a rub with 400 wet, then wax and grease remover before applying any filler.  Is prepsol a similar thing?

I have had trouble too with crumbling on very thin filler sections.  I find on such thin sections you can afford to have a little more hardener to get a better finish.

Hope someone else can be of more help

Dave

[hawk]

It sounds like you are using the bog that painters can use that fills small imperfections before spraying.As this bog is very easily sanded and quite creamy in texture .Hope this is of some help . That kind of bog needs to be applied over normal bog as a last coat to fill any pinholes or can be applied over paint if lightly sanded with say a 320 paper Cheers Greg

[Glenn 'Stinky' Stankevicius]

Sounds like the wrong gear or a bad batch there Leon, unless the acid in the metal is the problem.

I just went through this last week, as luck would have it the bog (actual product name) I picked up was made locally so I called them for instructions.
They reckon to apply to bare scuffed/sanded metal, then go through the priming and painting process.

[fccool59]

Its not the micro filler you are thinking of blu fc, it is a normal 2 part filler in a big can.
I am a little worried that it was on clearance becuase it was a bad batch or that the acid I treated the metal with could be reacting with acids in the bog, having done so many rust repairs, extra horsepower and low suspension I need the bog to flex and bond well, not like this stuff.

I have heard of people prefering to prime before bog but I reckon this would not allow etching acids in the bog to bond to the steel but I have heard of a lot of people doing it in that order.
It seems at worst over the lead were possibly the acid has reacted with the lead, does any one know if its bad to get the acid on the lead?

[Glenn 'Stinky' Stankevicius]

I have heard more instances where bog goes on steel rather than bog on primer now. The latest Street Machine mag has a piece on using bog on the bonnet of their Galaxie. They applied it to bare metal.

[SRVLIVES]

Street Machine, Jan 2005:
Story: Andrew Clatworthy (streetneat) and Craig Parker

If you're doing any bodywork, there's a good chance you'll be playing with plastic (polyester) filler, often called bog. There are three basic types of bog, all consisting of a base plus a catalyst (hardener).  Generic, lightweight plastic body filler is the one most commonly used for body repairs.  It's hydroscopic (absorbs water), so don't wet sand it or expose it to moisture before painting.

Fibreglass filler is similar but it's mainly resin mixed with fibreglass strands, it's much stronger than regular filler, making it ideal for bonding things together and filling holes.  It's not hydroscopic, so it's good for sealing repairs.  It is sandable but fibreglass filler furs up at the edges when you try to feather it out.  It's intended to have a skim of regular filler over the top to achieve a smooth finish.  The third type of filler is a fine finishing filler for repairing minor imperfections such as hail dents and small nicks and scratches, and it's the only filler that can be applied over paint.

When mixing and applying bog, don't pile it on.  It's meant to be used less than 2 mm thick - 10mm maximum.  Shrinkage does occur, so in thicker applications apply multiple layers and sand between layers.

Too little hardener and the bog will take too long to go off; to much hardener and you'll significantly cut down the workable time, and create excessive shrinkage and heat - it can get hot enough to warp panels.  Mix on a smooth, flat surface and make sure you blend the hardener right through as an unhardened spot of filler can ruin an otherwise perfect job.

Use a wide, flat applicator for mixing and applying filler.  Cheap plastic applicators are fine for a one-off job but if you're going to be doing a lot of filler work, invest in a decent set of steel-blade applicators.  They'll last for years if you thoroughly clean them after each use (as with your mixing board), which should be done before the bog hardens on them.

Don't contaminate your bog or hardener.  Be wary of dropping hardened bog or traces of hardener into your container otherwise lumps in the bog will make smooth application impossible.  Be quick when mixing.  You've got about a minute to mix in the hardener and three to four minutes for application.  Work time varies by up to two minutes with the amount of hardner used.  Once bog begins to go off, it hardens quickly.  Don't continue applying filler once it goes beyond the thick, honey-like state - it won't adhere.

Apply the filler over a larger area than the actual repair - at least 50mm all around.  Never apply plastic body filler over painted surfaces as it won't stick - it can't key properly and will delaminate.  Be quite generous when sanding away paint around the repair area as this allows you to properly feather (sand smooth with the surrounding surface) the edges of the filler.  Never attempt to get all your bog in at once - several applications are normally needed.  Initial layers can be roughed down with a cheese-grater file before the filler completely hardens - after five minutes, until about 15 minutes.  After that, leave all sanding until the filler has fully hardened, at least 20 minutes.  Happy bogging!

NB: Isn't my wife just the best typer!  

[fccool59]

thanks srvlives, good article but kind of as basic as my knowledge on bog, however this kind of confirms a few things I thought before but have a been little mislead to think otherwise.
I got most of the rear quarter done and a quick coat of 2k etch primer on but pretty rough as I was trying to hold a tarp over my head to prevent the light rain from getting in the work, It was also dark and I was had a light in there with me but it burnt a big hole in the tarp so I moved out the light and did it in the dark but while moving the light my tarp droped in the wet primer so I sprayed more over the top and ended up heavily covering my bog wich wanted to try and dodge with the etch primer.
being way thicker than I planned to put it on the etch primer started sagging in spots as the brand new suction  gun splattered and coughed missing spots and flooding others.
for the next ten minutes every bug in seven hills decided to have a bug meeting in the heavy bits.
It was supposed to be a light even mist only on the steel but didnt really work out.
hopefully the acid in the etch primer will be gentle on the bog.
There is something weird about this etch primer, everytime you pop the lid rain falls without fail, even after a long run of good weather.
I guess all in all it went ok, my wife just mowed and I didnt get any grass in the primer

I havent been able to find info on the conditioning / deoxidising acid being used before or after bog or near lead.!

[nicko]

Hi,just a little warning,you should never paint in a moist enviroment or high humidity,(re ,tarp over due to light rain),if you must do it out in the open then you are best doing it between 10 am and 2pm as thats the least humid and dry air time of the day,also never paint on a cold panel as both these enviroments will defect your paint with moisture that will show up later in little bubbles in paint even up to 3 months later.a hot to touch panel will effect paint badly also.
you will be well advised to sand this latest thick undercoat right back and redoing as soon as you get a nice day,
it would to be a shame to ruin your paint with whats under it after you have done so much hard work.
reguards Nicko

[fccool59]

nicko that was the aim, but as I said I cant open the tin without rain coming, I will probably rub it back off but we are expecting rain for the next couple of days and I have already bogged most of the panel, alternative was to have a bogged up panel covered in rust.
Also humidity was down to 35% wich is about as low as its been in the last 4 months after its been hanging around 75% through summer
I had been keeping the panel warm throughout the afternoon while racing against the clouds.
I am under the impression that the 2k etch is more moisture resistant than 1 k wich I dont like to expose for any longer than 1/2 hour before primer but I could be wrong.
It is pretty hard to get the panels done out there when I get home at around 6:20pm and cant make noise after 8pm and in between I have a hour and 40 mins to bog and prime a panel or let the bog sit till the weekend exposed and suck in moisture anyway.
to make things worse and push the stress level up in the red area, I live down low near a creak that is always foggy at night but I usually keep lights on panels prior to and after any paint is put on.
I had this same problem with the underside of the car, every time when I tried to open the tin it rained, after about 4 days I gave in to the weather and put on the primer with the tarp hitting the paint and rain and darkness, I must be cursed.

[nicko]

Hi,i did a bit of research about lead and bog,
you rough sand 80-120 grit,and put bog straight over it, if there is any problem ,then the only recomended undercoat that you can bog over is epoxy primer,you might be able to do it on other types but epoxy is the one they say is safe.
hope this is helpful
cheers Nick

[fccool59]

I just called up my uncle who is a vehicle painting teacher and he says the etch has to come of, the bog will need to dry out, the surface under the bog should be coarsely ground up with a 60-80 grit disc.
he also suggested epoxy primer as with epoxy primer you can strip the paint of, spray on the primer and do your repairs without worrying about the weather, as nicko said you can bog over the top of it and the bog will stick, another primer is then put over the top.
That sucks to find out now becuase I started with acrylic primer then changed my mind and bought 2k etch and HS and I dont want to buy it all for a third time but it would make things nice and easy in my conditions.
I had previously read about epoxy primer but when I asked my paint supplier about it he just looked at me like I didn't know what I was talking about and said no primer could be bogged over or left in the weather.
Apparently to get this stuff you need to go to a ppg dealer and the second pimer is available in a cheaper line not under the ppg label, all up it would cost about $300 for both with hardner to do the whole car up to the colour stage.