gluing after airbrushing

You really want plastic to plastic contact at the glue contact point of the two parts, so I scrape a little paint away at the contact points. I've found it doesn't have to be the entire area that will make contact though. That said, the old Model Master Black bottle glue melts the paint anyway but I don't like that much paint melted into the welded bond. I can't speak for Tamiya glue, I don't use them.

You'll need to remove paint from the join points before cementing them together.  You can sand, scrape with a #11 blade, or a really gentle way to remove the paint is with a Q-tip dampened with Isopropyl Alcohol.

I'd take a lot of those videos with a grain of salt, because I have seen many of them where the builder puts Tamiya Extra Thin on their parts and THEN puts the parts together.  You have to be really quick in order for that to actually work, and the pieces they put together probably fall apart if subjected to any stress, since the cement was already mostly evaporated and didn't actually melt the plastic.  The same thing probably would happen to their parts cemented together with the paint still on the mating surface.

You should also experiment with different types of adhesives for different attachment tasks.  2-part epoxies, super glue, and even Pledge Floor Care are all great adhesives for different situations, and none of those (with the exception of super glue) require the removal of paint to work well.  I use the Pledge Floor Care for attaching small clear parts and small photo etch parts with a significant mating surface when absolute invisibility of the adhesive is needed.

Many really good model builders paint and then cement, without scraping joint free of paint. Their work looks just fine, so that method clearly works for them, can't argue with success. 

I always protect joint surfaces, by either scraping away paint or in some cases masking with tiny tape strips. When this subject was brought up in the past, I experimented with leaving the painted surface alone and just painting as usual. The cement did indeed attack the paint, (both acrylic and enamel,) and did attach the parts together.

I allowed two days of cure time, (to ensure the softened paint had sufficient dry time,) then strength tested the join. It did take a little effort to pull them apart, but not nearly as much as clean joining surfaces. When the parts were separated I saw paint and cement in some areas that were not hardened, still a bit moist, and no sign of an agressive attack on the joining surfaces.

Painting and then cementing is probably OK, as it will still provide enough strength for normal handling. But for wing to fuselage, landing gear, tail surfaces etc, better to protect join surfaces from paint. Just my thoughts.

I hope others will add to this, it's an interesting subject.

Patrick 

I've had no disasters or even issues using Tamiya Extra thin after painting,now I'm not running a bead down a painted seam,that would ruin the paint job,but if I have the opportunity to do it from the inside,or a hidden joint,or perhaps inserting landing gear,*** pit shifters,I find the glue just melts everything and makes a bond.Not saying you should do it,but again I have had no problems with builds falling apart.

I have also applied extra thin to two sperate edges to at least start it,then added more glue once joined.

Iso does not work on real enamal.  While I usually scrape by above methodds, sometimes cut smsll pieces of masking tape and apply to glue areas before prind anp painting, removing just before I glue.

i

missileman2000

Iso does not work on real enamal. 

It works on all paints made for models, and can even strip paint that has been on a part for more than 20 years. 

How do you guys that use ISO to rid paint in glue areas keep it contained to that area only ?

My X Acto blade I scrape with goes where I put it ( I can still screw up but it's not like liquid ISO running away . And I mentioned already I keep it inside the perimeter to be glued, so not exactly all paint is scraped away. But I've found as long as there is some bare plastic contact within the glue area that all holds well.

missileman2000

While I usually scrape by above methodds, sometimes cut smsll pieces of masking tape and apply to glue areas before prind anp painting, removing just before I

Dear Missileman2000.  This is something I've never thought of, but I like it and am going to give it a try.  Thanks for the tip.

oldermodelguy

How do you guys that use ISO to rid paint in glue areas keep it contained to that area only ?

My X Acto blade I scrape with goes where I put it ( I can still screw up but it's not like liquid ISO running away . And I mentioned already I keep it inside the perimeter to be glued, so not exactly all paint is scraped away. But I've found as long as there is some bare plastic contact within the glue area that all holds well.

 

As I said in my previous post, I use a Q-tip that is just dampened with Isopropyl Alcohol.  I dip the Q-tip, and then blot it on a paper towel to leave it just barely damp, so it doesn't run from the area it is being applied.  Its really good for situations where you're removing paint from an edge and you want to avoid the potential for chipping the paint away from where you're not trying to remove it.  It all depends on the situation and where you're removing paint.  Sometimes scraping is best, and other times alcohol is best...again, where you're concerned about possibly chipping adjacent paint while scraping.  I have also used double-sided Scotch tape to temporarily stick two parts together to paint them, and then I can pull them apart later for ease of access to other things on the assembly, and the mating surfaces of those two parts won't need any paint removed because they masked each other by being temporarily assembled.

Eaglecash867

 

 

missileman2000

Iso does not work on real enamal. 

 

 

It works on all paints made for models, and can even strip paint that has been on a part for more than 20 years. 

 

Do you consider Testors enamel made for models?

missileman2000

Do you consider Testors enamel made for models?

Yes.  That is one of the paints I use regularly...Model Master Enamel (I don't use their Acryl line because its garbage, IMHO) and square bottles.  Isopropyl alcohol removes them all.  Acrylics, lacquers, all of them.  I'm not in the habit of posting information here based on theories and guesses.  I won't give advice or input on something when I haven't actually been doing it myself.  I don't like wasting peoples' time by doing that.