Cleaning parts before assembly and painting

[airfixian]

When cleaning parts in water and detergent is it enough to just let them soak, or do you have to brush the parts down?

[Rocket Ron.]

I add a splash of vinegar to the soapy water and give the sprues a light going over with a soft nailbrush.It seems to work.

[Sailorman]

I use a toothbrush. Not my own... I have one dedicated tomy models  😆

[Biggyinn]

The toothbrush comment was so good it appeard twice!

[Sailorman]

Thanks for pointing out the double post Biggyinn.  I've removed it.

[wijnands]

I did a test recently. Took one sprue, applied primer. Took another sprue and sloshed it around in some warm water with dishwashing soap. Then primed it. Primer on the second sprue adhered a LOT better.

[graham martin]

I have only ever bothered cleaning parts if they were resin, but perhaps i should do the same with normal plastic as well. Is the release agent the main reason for washing ?

[Mattoo]

I have only ever bothered cleaning parts if they were resin, but perhaps i should do the same with normal plastic as well. Is the release agent the main reason for washing ?

I think so, though I'm led to believe that's only an issue with resin or other less mainstream manufacturers.   I often wash with soapy water after building but before painting just to wash any dust and debris off and any oils from my own sticky fingers.   I also imagine that with "hot" paints it's less of an issue but acrylics might not be able to bite through any grime so well.

[peebeep]

 

I think so, though I'm led to believe that's only an issue with resin or other less mainstream manufacturers.

 

Resin casters need to use a generous amount of release agent, especially if the casting has deep undercuts. Excessive release agent is not usually a big issue with mainstream maunfacturers, although you might come across it from time to time and it's pretty obvious when it happens. I mostly use hot primers and lacquer based acrylics and other than giving the surfaces a wipe I don't usually wash them with any detergent. So far paint adhesion has not been a problem.

[LeonF]

I rarely wash sprues and have had few issues with the standard plastic kits and  acrylic paints.

However there are exceptions to every rule and Airfix (and some old Italeri) kits do throw up the occasional concerns. The most problematic was the blue-grey plastic used by Airfix for a few years which seemed to ooze oil. Thankfully the more recent  kits moulded in grey are much better in this respect.

[Sailorman]

In most casescI don't wash the parts before building. The washing happens automaautomati when I sand the joints down since I use wet and dry sandpaper with water and washing up liquid

[Gluey fingered Dave]

Yeah, quite hit and miss about washing out of the box because I'm lazy and rationalise it away as only affecting the interior parts that you probably won't see under the weathering and canopy but do use a soft toothbrush and plain old dishwashing detergent when I do. It does make a difference to the feel of the plastic and the way the water beads off it even on modern mainstream manufacturers so there must be some manufacturing residue left. Doesn't seem to interfere with paint or if it does it's less significant than airbrush and thinning settings. (I use acrylic Tamiya or Gunze) 

I will wash the entire model down prior to painting the exterior though as the little bits of sandind dust and finger print oil does stuff up the finish of the paint. 

[Peter s]

I never bother washing the sprues (lazy) but I airbrush a cost of Tamiya paint diluted with alcohol before I paint with any other sort of acrylic paint. Vallejo model air doesn't work on unprimed Airfix but a light coat of Tamiya solves most problems without obscuring detail.

[dabhand]

I have washed parts prior to assembly, but have found that as construction progresses there is often a need to sand down seams/filler etc, and doing this usually results in the partially completed model receiving a wash in warm, soapy water.  Some kits, generally older ones or remoulds of old kits have had visable release agent on them, particularly on concave surfaces, and this warrants a wash. 

I always do this a a bowl and not the sink.  The washed kit is inspected for loose/missing parts on removal from the bowl and the residual water/washing up liquid checked for loose parts before draining. 

I have found that a light wash before finishing [ie painting] does provide a better surface than otherwise if only that dust otherwise attracted to a model about to be painted is generally removed.