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Spray painting problem


Guigsy

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Ok. I have sprayed my old dash on my facelift. And also the one on my UK spec car without problem.

 

Today i have filled in the 2 holes at the bottom of the heater pannel nearest the driver as i no longer need the buttons.

 

It all went well. Filled in nicely and smoothed over with a few grades of wet and dry. I went to spray and put on a layer of primer (halfords plastic primer).

When i returned a little later to sand and do a coat of paint the best way i can describe it is that the primer has cracked near where the edge of the filler is and also in a small area arround the edge of one of the holes where i also did a little touch up.

 

The filler hasnt seperated from the pannel or anything its literaly just the paint that has "cracked"

 

A similar thing happened when i was modifying and spraying my pillar pod. In the end i gave up, sanded it the best i could and just sprayed on some satin black paint as it was in an area you dont see much.

 

I obviously want this to look propper as its right infront of me on the dash and im a picky bugger!

 

Am i doing something wrong?

 

Could it be that the place im spraying is out in the porch type area that leads to my back yard and there isnt any heating and its quite cold?

 

:help:

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Did you do the prep inside the house bud? Could be that it was prep'd in the heat and the change in temperature between inside and when you took it out to the porch has caused the plastic to constrict causing the 'crack'.

Off topic, but did you have to do the same level of prep for your facelift dash as you would for a pre-facelift dash (thinners, scraper etc that I've seen in some write ups)?

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yeah i did the prep inside the house. Its been sat out the back for a while so ill try doing some more prep out there :p

 

Na my facelift dash was dead easy. Just sprayed it as there is no rubber coating, The non facelift dash was a complete PITA though!

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right ok, there are 2 things i could suggest:-

 

one mistake:- everyone makes it so dont worry. filler shouldnt be used to patch holes, its used to fill small tiny titchy holes and scratches. what you should have used it fibreglass. not the sheets and paint brush on with the liquid well you can but its messy and results are hard to get perfect but anyways tinned fibre glass that you mix with hardner and it looks and spreads exactly like filler. now when fibre glass dries it goes solid. thing is with filler that it absorbs moisture and can take ages to dry if not enough hardener is used. any tiny flex in the material that you fillering can cause the filler to crack. the fibreglass rock hardens and because of the strands in it doesnt crack easy. once you sand down the fibre glass you have a strong non-flexing base to put on filler, filler will stick to the fibre class and give you the smooth finish. remember you should always be using a lil bit of filler, if you use a lot then your just being lazy and later on eventually the filler will crack and you will have to re-do it.

 

now that should help the overall finish however i do believe that your describing something called 'Reaction'. its like the paint has clotted up and not stuck leaving like a skin burn mark thats squiggy and streeky lines. unfortunately that means the surface you were working on has had something exposed to it. was the panel cleaned? never ever wipe a panel with thinners. did you use a pre-paint solution or wipe? you will have to sand that area down again, and also, put thin tiny layers of primer on, dont chuck loads of it on, simply dust it on, come back all ok, dust more on, and so on and then simply flat down and paint.

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Ive used fibreglass before and i still have some left but i didnt fancy doing it again :p

I got something (cant remember the name of it now) but its made for patching holes in plastic bodywork. It stank and came with some hardener, Smelt exactly the same as fibreglass resin. Maybe i better read the backet again :p. I put some fine aluminimum mesh behind the holes and pushed it into the space to give it a base to cling on to (as it said on the instructions)

 

I didnt use thinners or anything like that. Just pulled the dash out of the car. Sanded it down, washed it off, dried it and then sprayed.

 

The strange thing is it happened in areas where the primer didnt have any filler stuff under it.

 

Ive tested again after sanding it down once more and without getting rid of it all, Just sprayed some silver paint ontop without doing even more primer and it seems to have taken. But ill have to sand it again tomorow and do some more coats before it comes out properly.

 

I think most likely ive put too much primer down in one go in my haste to get it finished tonight :(

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