Pete Harvey Posted October 4, 2009 Share Posted October 4, 2009 Is it Possible to use Etching Primer on a model that is 90% brass and 10% Resin? Has anyone used etching primer with this combination and what results did you get? Pete Link to post Share on other sites More sharing options...
77philg Posted October 5, 2009 Share Posted October 5, 2009 Is it Possible to use Etching Primer on a model that is 90% brass and 10% Resin? Has anyone used etching primer with this combination and what results did you get? Pete Would be the same as spraying etch primer over white metal, cant see it reacting with the resin .you could always spray brass and mask off resin bits,then spray the lot with halfords primer to be on the safe side phil Link to post Share on other sites More sharing options...
Guest jim s-w Posted October 5, 2009 Share Posted October 5, 2009 Hi Pete I have used JLTRT etch primer over a model that was the other way round, 90% resin and 10% brass with no problems HTH Jim Link to post Share on other sites More sharing options...
Pete Harvey Posted October 8, 2009 Author Share Posted October 8, 2009 Does anyone know of a shop that stocks the JLTRT paint products as there web site has not sales cart? Pete Link to post Share on other sites More sharing options...
RMweb Gold The Fatadder Posted October 9, 2009 RMweb Gold Share Posted October 9, 2009 Silly question... Whats the advantage of using etch primer over say the stuff you get from Halfords? Link to post Share on other sites More sharing options...
Andy C Posted October 9, 2009 Share Posted October 9, 2009 I dont know the technical / chemical reason, but Etch primer does adhere better to bare metal than your bog standard halfords primer which has a tendency to chip easily when on the bare brass. I use the two part comet etch primer, it can be brushed on very easily and quickly and because its thin, no brush marks - Ive always been a bit wary of sticking a primer through my air brush for some reason. The Comet two part is a bit messy to prep when mixing but I have found its as tough as old boots when its on. Edit: oh and ive used it successfully on the milky bar bits of kits as well - just to answer the OP!!! Link to post Share on other sites More sharing options...
28ten Posted October 9, 2009 Share Posted October 9, 2009 Does anyone know of a shop that stocks the JLTRT paint products as there web site has not sales cart? Pete AFAIK it's only available direct, you have to give them a ring Link to post Share on other sites More sharing options...
Buckjumper Posted October 9, 2009 Share Posted October 9, 2009 AFAIK it's only available direct, you have to give them a ring Last time I did, delivery was very fast. Link to post Share on other sites More sharing options...
Pete Harvey Posted October 10, 2009 Author Share Posted October 10, 2009 Have you got the details for them Buck? Pete Link to post Share on other sites More sharing options...
halfwit Posted October 10, 2009 Share Posted October 10, 2009 "The etching primer is also an excellent primer for covering cast resin. Resins tend to reject paint that is too thin and wet". So says Ian Rathbone in his Painting and Lining book. Link to post Share on other sites More sharing options...
Ian G Posted October 12, 2009 Share Posted October 12, 2009 i use the 2 part etch primer from Precision Paints with no peoblem. Ian G Link to post Share on other sites More sharing options...
bertiedog Posted October 12, 2009 Share Posted October 12, 2009 Resin, or any plastic should be OK with any make of modelling etching primer, which were mainly originally introduced for use on steel, rather than brass, copper, or bronze. They all contain a mild acid, which cures to neutral as the undercoat/primer paint dries. The paint is basically the same as any other primer, but usually is a thinner paint than, say, Halford Primers and undercoats. The more advanced types are two pack style, and the mix starts the action, and results in better neutralization of the paint before the next coats of paint. Most etching primers are much slower in setting hard, and extra time should be allocated to drying the product off before the next coat. This is a very big difference from cellulose primers like red oxide, or grey primer, where as soon as the paint is touch dry, which with an airbrush may only be seconds. I prefer to paint the model with an etched primer and then allow to dry, which can take several hours, and then warm the model to further cure the etching primer. It toughens the primer and ensures it will take cellulose if needed, but of course enamel or coach enamel can be used. Acrylics can be painted over an etched primer as soon as it is dry, but I find there is a bit of extra rejection, and beading, of the acrylic paint, if it is thinned too far, so slightly thicker mixes are the order of the day compared to spraying acrylic paint of any make over Halfords primers. It really pays to clean the resin parts very carefully, moulds can contain lubricants, which do enter the top surface of the resin a bit, and the best material is cellulose thinners to clean it with, although meths will do. Also a good general purpose cleaner is any of the Acid domestic cleaners like Cillit Bang and it's ilk, they all clean and mildly etch the metal surface as well..a bonus to give the etching primer a head start. Stephen. Link to post Share on other sites More sharing options...
artisan100 Posted October 13, 2009 Share Posted October 13, 2009 Just to confirm above replies, the Comet etch primer chemically bonds with the underlying brass, but also acts as an effective primer on resin, whitemetal, etc. Spray on acrylic primers, such as Halfords, are really just an undercoat. Geoff Link to post Share on other sites More sharing options...
bertiedog Posted October 13, 2009 Share Posted October 13, 2009 Just to confirm above replies, the Comet etch primer chemically bonds with the underlying brass, but also acts as an effective primer on resin, whitemetal, etc. Spray on acrylic primers, such as Halfords, are really just an undercoat. Geoff Geoff, a little bit more, There's no actual "chemical bond" with the metal, just basically a cleaner, firmer bond to conform the paint to the surface in the case of copper, and also brass and bronze, plus a small chemical etching effect......mechanical abrasion ( abrasive paper or glass fibre brushes), can give as good a bond in most situations, but model surfaces are difficult to prepare in this way, so an active primer like etch is very useful. Resin gets no chemical advantage from an etched primer, but it works well anyway. With steel it is different, as phosphates are formed which act as inhibitors to oxides, they stop rust,( iron oxide), under the paint. The etchant in "cleaning" the surface may slightly bite the top surface of brass, this is point of using the etching primer, but the main advantage is that they are tougher than a simple primer, which in the case of Halfords, can be "spray can acrylic" or canned "cellulose coach enamel" for spraying with an airbrush. For the toughest primer "etch" is hard to beat, without resorting to baking the cellulose primers, which toughens them a lot, and a "mixed model" with resin, and glue, is not the best thing to bake paint on! Any available over the counter consumer type Acrylic primer is naturally less tough than oil based mediums, but 2 part acrylic etch is available, and is the best at being hard wearing, and bonds well with both more acrylic colour top coats, or cellulose top coats. Stephen. Link to post Share on other sites More sharing options...
wcrpaul Posted December 3, 2012 Share Posted December 3, 2012 I found this thread very helpful - especially AndyC's comment about being able to brush etch primer with it being thinner in consistency. I obtained some Railmatch 1-part etch primer & Xylene thinners to finish two MSL brass & white metal (with auto chip & dent filler used for fettling) EM1's, but having read the warnings on the labels I found the prospect of airbrushing this stuff very scary. Due to its being thinner I'm guessing etch will not provide the covering properties of conventional enamel primers, so, having applied the etch, do you then need one or more coats of conventional enamel primer or can you move on to a first coat (of several) of colour? Paul. Link to post Share on other sites More sharing options...
tender Posted December 3, 2012 Share Posted December 3, 2012 A few RMWebbers on the Kit and Scratch building forum use UPOL Acid #8 Etch primer, available from Halfords. Link to post Share on other sites More sharing options...
45609 Posted December 13, 2012 Share Posted December 13, 2012 See here. Never had a problem spraying etch primer over resin, whitemetal or plasticard. I buy 2 pack etch primer in bulk which is much cheaper. I also have an old cheap air brush for spraying the EP so as to not run acidic compounds through the expensive equipment. Link to post Share on other sites More sharing options...
Anglian Posted December 13, 2012 Share Posted December 13, 2012 I've just bought a can of this: http://www.ebay.co.u...984.m1439.l2649 I'll see how it covers and may give a light dusting of Halfords over the top depending on coverage. I'm very unimpressed with normal Halfords primer, on metal it will just chip off and it's even worse on brass than white metal. On the can it lists 'trains' as an intended usage, so I'm assuming it means model trains… Link to post Share on other sites More sharing options...
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