Precision varnish lifting paint..advice needed

[vitalspark]

Recently spent a lot of time building a Dapol Railbus with brass interior and chassis with Hollywood foundry running gear.

I primed it with airbrush and Precision grey 50/50 thinned and three coats of precision green 50/50 thinned again.

Last coat allowed 48 hrs to dry then a satin varnish applied..again Precision PV72 thinned 50/50 with Precision PQ10 thinners exactly as advised but after about 10 mins the paint has reacted on the kit and has lifted through to the plastic and left the rest in a sorry state.

All prayed carefully with an Iwata airbrush and all previous paint coats were fully dry before next application and thinned with Swan lighter fuel.

I know someone will probably suggest this as the problem but I have never experienced this with the same combination and Humbrol thinners and Swan is widely used I believe..is there any hard evidence to point to this as the culprit rather than speculation?

I am getting desperate now and don`t know if a new build is the best option or can I succesfully remove and repaint with strippers?

I need this ready for the Wigan show.

Thanks in advance

 

Dave

[ladysplicer]

Recently spent a lot of time building a Dapol Railbus with brass interior and chassis with Hollywood foundry running gear.

I primed it with airbrush and Precision grey 50/50 thinned and three coats of precision green 50/50 thinned again.

Last coat allowed 48 hrs to dry then a satin varnish applied..again Precision PV72 thinned 50/50 with Precision PQ10 thinners exactly as advised but after about 10 mins the paint has reacted on the kit and has lifted through to the plastic and left the rest in a sorry state.

All prayed carefully with an Iwata airbrush and all previous paint coats were fully dry before next application and thinned with Swan lighter fuel.

I know someone will probably suggest this as the problem but I have never experienced this with the same combination and Humbrol thinners and Swan is widely used I believe..is there any hard evidence to point to this as the culprit rather than speculation?

I am getting desperate now and don`t know if a new build is the best option or can I succesfully remove and repaint with strippers?

I need this ready for the Wigan show.

Thanks in advance

 

Dave

Hi dave ive used precision varnish on a few locos and had no trouble ive always used railmatch paint tho and not precisions paint i reckon it could be the swan lighter fuel ive never herd of that being used before to thin paint i thin my paint with normal thinners and always use an airbrush if you have used the lighter fuel before and it was ok maybe you got a dodgy tin and reacted to the varnish i would remove the paint and have another go but use normal thinners (turbs) this time and see if its ok with that let us know how you get on.

 

cheers

[bertiedog]

It is my opinion it is the thinners, Paint formulas alter, new regulations etc, and although things once worked with non makers thinners like petrol, it really is a practice that can take you down a bad path.

 

I have used cellulose thinners with synthetic enamels many times, and petrol on many occasions, no troubles, but with paint re-formulations these day for safety reasons, the correct thinners must be the best advice.

 

I never thinned varnish with anything but the right stuff, varnish is the most troublesome of all paints, and that is why Precision Phoenix offer the correct special thinners.

 

After all it is not normal painting practice to use cellulose thinned varnish over enamel, and that is virtually what the petrol thinned varnish is, it has simply dissolved the surface, evaporated and ruined the paint underneath.

 

After saying this I do finish with both Rustins cellulose and Testors over any finish, acrylic, enamel, or synthetic enamel, but it is the technique that makes it work, it is micro dusted on, allowing constant drying so that the thinners have no chance to attack the paint.

 

I suspect that despite your best efforts the varnish was too thickly applied, with too little time for the varnish thinners to properly evaporate, there should never even be a hint of a wet edge or surface whilst using the airbrush with such high octane thinners..

 

Hope this explains what happened, looks like strip and re-paint, and use the right thinners or work very very slowly!!

 

Stephen.

[vitalspark]

Thanks guys for all your replies. I will try and salvage what I can and reprime and re paint...perhaps I will leave the final varnish coat off though and just apply it with a fine brush over any lining etc.

I started using the lighter fuel as thinners after the advice of more than one experienced modeller..I can`t remember who initially told me but it was at one to one demos at a finescale show with well known names..certainly much more knowledgeable than myself.

It made sense as it was suggested it evaporated the instant it left the nozzle and only the paint hit the model.

The logic seemed good and I have used it many a time but as you say perhaps the formulation of the paint or fuel has changed since and I agree varnish is a sod to work with anyway.

One interesting thing I was told then was thatv it must be Swan..Ronsonol would not do...perhaps Swan has been bought out!

 

I am running out of time on this but if it is salvageable it will be running on Alloa at Wigan...fingers crossed.

 

Thanks again

 

Dave

[Platform 6]

Hi Dave,

 

Sorry to hear about your experience with the railbus.

 

I've had a couple of similar experiences with spray painting in the last few years. Many failures and then a lot of headscratching resulting in the building of a Parkside kit to soothe the nerves!

 

I've also heard advice given about using petrol lighter fluids as thinners, but with the make up of paints/varnishes changing to follow regulations some of them obviously won't work. I still wonder if a tin of Humbrol thinners from about 10 years ago was a deliberate corporate attempt to attack any colour of Mainline Parcels Van   

 

I think Stephen (bertiedog) gives excellent pointers towards good results. They make sense to me anyway. It's one step or change at a time to get the result that you know works.

 

No help with a deadline looming I suppose - good luck anyway. I'll say 'hello' at Wigan.

 

Andy