Topic: New paint lifting on side panels

[ChrisR]

Hi, I'm hoping someone might be able to help with a problem I've got with the side panels on my 550f. I sanded them right down to get rid of all the old paint that had been applied by previous owners over the years, filled the scratches and holes, undercoated with cellulose primer then topcoated with cellulose, too. I've clearcoated over the top of that as well. Now I've got some bubbling of the paint as if it hasn't adhered to the fibreglass properly. I might have rubbed through the gel coat when sanding down and wonder if that might be reacting with the paint in some way. I cleaned the surfaces quite well before applying the paint. I had quite good results with the petrol tank painted in the same way so don't think it is anything to do with the paint but perhaps a reaction with the fibreglass.
I'm going to have rub all down again  and wondered if anyone had any ideas as to what was going on and if anyone had found some sort of blocking undercoat that might prevent the reaction from happening again.
Any advice would be very welcome.   Chris.

[grumburg]

Side panels are a real pain. Even the original paint crazed over time. I have had very good luck with Duplicolor primer-sealer. Take off all the paint ( especially if there is enamel underneath.) wipe down throughly with Prepsall to remove all old wax and silicones. Apply several light coats followed by a wet topcoat.

[tomkimberly]

Use Killzs primer sealer in the spray can avalible at most hardware stores. It woks wonders for peparing plastic and fiberglass for painting.

Tom

[ChrisR]

Thanks for replying so quickly. I think I have seen Duplicolor over here and will try and get some. Not sure I've seen the Killzs primer but I'll ask.  Not looking forward to taking off all the paint I lovingly applied a couple of weeks ago. However I want to get a decent finish (i.e. paint staying stuck to panels!) as I was lucky enough to get some decals for the bike from Reproduction Decals before they stopped doing Honda ones and don't want to have to pay for some more if the paint starts lifting again. Having said that I believe Sunrise Graphics  www.sunrisegraphics.co.uk/   does decals for old Hondas, etc over here but I believe they are a bit pricey compared to Repro. Graphics even with the shipping.
I'll let you know how I get on and try and do some pics when done. I'm not going for a concours finish, just something acceptable. Cheers    Chris

[cmorgan47]

i've had good luck with duplicolor primer too.  typically i sand the fiberglass bare with a light paper, then rough it up with something heavier (80 or so).  then put a few coats of duplicolor primer and sand it smooth.

haven't tried primer-sealer yet, but will on the next paint job as i was reading a book the other day that was really talking it up.

[kaceyf2]

Hya bro, the only real reason for the "bubbleing" that you are having on the side-panels,would be some sort of humidity issue...
First off, i am a time served paint sprayer, which I went into after first becoming a mechanic,sort of logical progression.......
One Golden rule, never, (under any circumstances) wet flat body-filler, as it is semi-porous and you will never dry it out properly to stop the inevitable "bubbleing", no matter what.
Also, there is no reason too, as you can go from 180's grade freecut, direct to 240's freecut, direct to primaring. If this is not the issue, did you wet-flat the primar? and if so, how carefull/ hasty were you before topcoating?
If this wasnt the issue, did you have adequate heating in the spray area? ( for instance was it raining out?)
If it was not "water retention" in one of its guises, then it could be dirt that you are seeing under the paint, giving an "appearence" of "bubbles".
The only other possibility, is of course a "reaction" of some kind, but this is totally unlikely, as all reactions that I have encountered have been of an instantly recognisable variety, like "crows feet"(cellulose on top of synthetic type mistake) or "silicones" ( tiny saucer shaped depressions in the finish caused by a polish containing silicone in the vicinity/atmosphere)
Or indeed "water bobbles" ( little bubbles of water blown through the airline and "scattered" accross the topcoat, caused by not draining the compressor/ and or not having an adequate - in - line - water trap between the compressor and your gun.......ALL of which are totally avoidable..........
ANYWAYS,
reactions are recognisable, as they have peculiarities unto themselfs, yours ( without looking at it, just going on your description) appears to be water born.
Also, (and as well as) the side panels flex, and if you look at old panels that have stood the ravages of time, and carefully examine the laquer, you will see lots of "stress-lines" in the laquer , and each time the side panel is pulled off or put back on, it will flex causing the above condition.
This can be avoided in future, If you use a good 2k system and add a "plasticiser" in with the mix, the plasticiser is designed to allow 2k to flex with the panel, and is excellent for items such as side panels, fairings, and other flexible items.
However, a decent plasticiser can cost around £40.00, so it aint cheap, but on flexable items its the professionals choice.
Another golden rule, you will only get a 100% finish, by preperation thats 100% correct +100% cleansliness, skip on these and you dump on your finish, plain and simple.

Hope this helps.

[ChrisR]

Thanks Kaceyf2. I think you've hit the nail on the head. After sanding back the old paint I filled the holes and depressions in the bare fibreglass panel, then wet sanded it smooth. Then primered it and wet sanded again. I can't remember the time interval between the filler wet sanding and the priming but if as you say the filler retains water then perhaps it wasn't long enough to let it dry out properly.
The bubbling is in patches that might correspond to the areas of filler underneath.
It never occured to me that the filler might retain moisture. Duh! Repeat after me -  DON"T WET SAND FILLER.
Can it be dried out enough to take paint or am I going to have to dig the filler out and start again?
I really appreciate the time everyone has taken to reply - this place is great.
Chris