Glueing after painting.

[Guest]

Once you have painted individual items that need to be attatched to your kit, can you simply apply the model cement or do you need to remove a small portion of the paint in order for adhesion to take place. Ive never really been sure about this. How and what method do you use. Cheers

[Guest]

Always scrape / sand the paint off! Otherwise you're gluing paint to paint & getting a very weak joint.


If the part is really small or inaccessible, liquid glue can remove the paint by using a few extra brush strokes.


Cheers


Patrick

[papa 695]

I agree and do the same as Patrick

[Guest]

First of all "glue"(not) cement actually welds plastic to plastic ie softens the plastic which then can be joined much the way in which metal welding occurs.


Cement is not a glue it is a solvent which has been said melts paint as well as the plastic. So even if you remove paint the solvent can creep as you apply pressure to the two pieces and spoil your paint job.


For me added on pieces I use super (cyrano) glue. But it depends on the circumstances. If you do use plastic cement in these circumnstances I would use MrCement S. apply to both parts leave a few secs then apply as then you will not find the cement has migrated to the paint.


Laurie

[Guest]

First of all "glue"(not) cement actually welds plastic to plastic ie softens the plastic which then can be joined much the way in which metal welding occurs.
Cement is not a glue it is a solvent which has been said melts paint as well as the plastic. So even if you remove paint the solvent can creep as you apply pressure to the two pieces and spoil your paint job.


For me added on pieces I use super (cyrano) glue. But it depends on the circumstances. If you do use plastic cement in these circumnstances I would use MrCement S. apply to both parts leave a few secs then apply as then you will not find the cement has migrated to the paint.


Laurie

So how does ' glue ' melt the plastic Laurie? Surely it contains a solvent of some sort?


To me glue & cement are different words for the same thing. Not in the construction industry though!

[Guest]

So how does ' glue ' melt the plastic Laurie? Surely it contains a solvent of some sort?
To me glue & cement are different words for the same thing. Not in the construction industry though!

Patrick dear please read what I have written me old cock.


Laurie

[BarryW]

It can also depend on what type of paint you use, what cement and whether it ia 'load bearing'.


Using acrylic paint and Mr S Cement I have found that in non load bearing areas you can get a perfectly good adhesion without scraping the paint off, applying the normal way using capillery action. Often the paint will 'crinkle around the join but more often or not it will look Ok when dry. If not then a touch of paint will do it.


I usually cement into place the internal structures on an aircraft this way and most of the time any glue marks are out of sight.

[geegad]

i agree scrape and you should be good to glue

[Guest]

As I understand it, one type (thin, very liquid) is just a solvent. You can brush it on to the the seam joining two parts such as the halves of a fuselage, held together and the liquid wicks into the seam, disolving the polystyrene plastic and, as Laurie says, like welding (except that welding adds metal as well as melting the steel parts). You can than gently squeeze the seam together and hold for about 20 secs when the join will be handelable and strong. An example is Mr. Clement S.


The other type is (I think) essentially polystyrene itself, disolved in the above thin liquid. Therefore, it adds poly, so this can be used for attaching an object to a surface, like a door mirror on a car. It will form a strong join by surrounding the contact area with actual polystyrene (although the first method for seams is also strong). An example is Humbrol Poly Cement.


I don't know which term is applied to these two approaches in modelling: cement or glue. Following terminology in woodwork, a glue is like the second (above) so for me it is a glue. I don't know what the first should be called. Solvent, perhaps.

[Guest]

The other type is (I think) essentially polystyrene itself, disolved in the above thin liquid. Therefore, it adds poly,

Did not know that Steve. Are you sure ? Humbrol say this


Usage


A solvent-based cement suitable for plastic model kits only.


Substrate


Common plastics used to manufacture model kits including polystyrene and ABS. The product works by melting the plastic on application and 'welding' two glued pieces of plastic together to form a strong bond.


Laurie

[Guest]

I'm not sure, I usually just glue it together once ive painted the plane parts. The glue usually takes a bit of the paint of anyway if you scrape it accidentally. Do what you think is best

[Guest]

I'm not sure, I usually just glue it together once ive painted the plane parts. The glue usually takes a bit of the paint of anyway if you scrape it accidentally. Do what you think is best

Think Blair if your way suits you stick to it. I tried a number of ways before


finding the way that suits my way of working.


I find that cementing parts together then filling sanding then painting to be the best.


If parts do not fit as well as they should be it does mean painting before hand has


been a waste of time.


I do leave off as many of the small tiddly bits as I can as I find they get knocked


off. These on average I fix at the end with super glue.


Laurie

[stona]

I glue plastic to plastic and never paint to paint. It's what the plastic cements (which are all solvent based) are supposed to do.


I paint detail after the small parts are assembled with magnification, fine brushes and a firm belief in the triumph of hope over expectation


Cheers


Steve

[Guest]

the triumph of hope over expectation

Such a life long ambition of mine Steve.


Laurie

[Guest]

I find that cementing parts together then filling sanding then painting to be the best. If parts do not fit as well as they should be it does mean painting before hand has been a


waste of time.


Laurie

I agree, sometimes there is glue left sometimes coming out of the cracks between the two pieces, which needs to be sanded down