Paint and assembly techniques

[jamesG]

When it comes to interior tubs for example, do you prefer to paint all parts first then remove paint where parts are to be "glued" or "glue" first then mask various parts and paint or something else.

For example. Seats can be installed then everything painted as one or parts can be tub and seats painted separate then paint removed where parts meet or areas where seats go could be masked parts painted then remove mask and assemble.

Yes I am aware that certain items may require a combo of techniques just curious as to preferred techniques or ideas I haven't thought of 

Edited August 1, 2020 by jamesG

[espo]

My suggestion would be to do as much of your masking and painting before you start assembling. The one exception would be in the area of the front seats. In most cases this will involve a seat back that may or may not blend with the front smoothly. Many bucket seats will have a chrome or some sort of trim that will define the seperation between them and that may mean that you could just paint as needed and then put them together. Bench seats in particular seem to have no defining edge on the 1:1 and this would require putting them together and cover the seem with some sort of putty and paint as you want before assembly of the interior. Also by painting everything before putting the interior together gives you a chance to do as much detailing as you want and it's much easier to mask that way. Hope this will help answer your question. 

[jamesG]

3 hours ago, espo said:

My suggestion would be to do as much of your masking and painting before you start assembling. The one exception would be in the area of the front seats. In most cases this will involve a seat back that may or may not blend with the front smoothly. Many bucket seats will have a chrome or some sort of trim that will define the seperation between them and that may mean that you could just paint as needed and then put them together. Bench seats in particular seem to have no defining edge on the 1:1 and this would require putting them together and cover the seem with some sort of putty and paint as you want before assembly of the interior. Also by painting everything before putting the interior together gives you a chance to do as much detailing as you want and it's much easier to mask that way. Hope this will help answer your question. 

Yeah, I understand that some things will demand paint prior to assembly such as an instrument cluster prior to adding the steering wheel and that it also depends somewhat on the intended level of detailing. I was just curious as to anyone's preferences or any methods I may not have thought of. 

I myself prefer to paint as much as possible and then remove what is needed to achieve a good "glue" bond. Exceptions would be engine block and trans. or seats that are two or more pieces.

[StevenGuthmiller]

I never remove paint or chrome from areas of parts to be cemented together.

If you're using the old model "tube" cement, or a liquid cement to join parts during final assemblies, I suppose you should, but there are a lot of better glues available today that don't require it.

If your parts are properly primed and painted to ensure good paint adhesion, there's really no reason to remove paint from joints if you're using a glue such as CA or epoxy for assembly.

I haven't used tube cement for models since the 80s.

Never liked the stuff anyway.

It takes too long to set, parts slide around, the stuff gets on everything except where it's intended, and I never liked the idea of a glue that bonds by melting the plastic, especially on exposed parts.

 

I paint every part independently, (except parts where seam filling is required) and glue everything together as needed with various types of glues that don't dissolve plastic.

 

 

 

 

 

Steve

 

 

 

[CabDriver]

I’m with Steve ⤴️

I know you TECHNICALLY get a better joint if you use the trick of welding parts together during final assembly with a suitable solvent glue (and that’s how I assemble parts prior to paint) but as Steve says there’s so many great glues on the market that don’t require you to start scraping paint off to glue parts together I’ve never done that.  I’m not SO rough with my built kits that they need that extra adhesion

[oldscool]

2 hours ago, StevenGuthmiller said:

I never remove paint or chrome from areas of parts to be cemented together.

If you're using the old model "tube" cement, or a liquid cement to join parts during final assemblies, I suppose you should, but there are a lot of better glues available today that don't require it.

If your parts are properly primed and painted to ensure good paint adhesion, there's really no reason to remove paint from joints if you're using a glue such as CA or epoxy for assembly.

I haven't used tube cement for models since the 80s.

Never liked the stuff anyway.

It takes too long to set, parts slide around, the stuff gets on everything except where it's intended, and I never liked the idea of a glue that bonds by melting the plastic, especially on exposed parts.

 

I paint every part independently, (except parts where seam filling is required) and glue everything together as needed with various types of glues that don't dissolve plastic.

 

 

 

 

 

Steve

 

 

 

What he said. I use CA as much as possible because it dries fast and forms a rigid bond. Solvent glue bonds always seem to feel flexible. If you want to check out what I am saying then do this:

Glue the wheels on a model with solvent cement and then do the same to another model using CA. When you sit the model down on a table you can feel how the one glued with CA feels very solid on its wheels. Like the old metal axle kits feel. I hope this makes sense.

[jamesG]

3 hours ago, StevenGuthmiller said:

I never remove paint or chrome from areas of parts to be cemented together.

If you're using the old model "tube" cement, or a liquid cement to join parts during final assemblies, I suppose you should, but there are a lot of better glues available today that don't require it.

If your parts are properly primed and painted to ensure good paint adhesion, there's really no reason to remove paint from joints if you're using a glue such as CA or epoxy for assembly.

I haven't used tube cement for models since the 80s.

Never liked the stuff anyway.

It takes too long to set, parts slide around, the stuff gets on everything except where it's intended, and I never liked the idea of a glue that bonds by melting the plastic, especially on exposed parts.

 

I paint every part independently, (except parts where seam filling is required) and glue everything together as needed with various types of glues that don't dissolve plastic.

 

 

 

 

 

Steve

 

 

 

I tend to use liquid cements more these days. What other "glues" dont require paint removal. I'm curious though I dont trust gluing to paint as the paint will always be the weakest link. I use ca sparingly due to hazing or fogging. 

Tube glue is a pain to work with but does a good job at bonding (though probably not the best). 

I'm curious as to why you dont like the idea of melting the plastic together.

 

 

[jamesG]

2 hours ago, CabDriver said:

I’m with Steve ⤴️

I know you TECHNICALLY get a better joint if you use the trick of welding parts together during final assembly with a suitable solvent glue (and that’s how I assemble parts prior to paint) but as Steve says there’s so many great glues on the market that don’t require you to start scraping paint off to glue parts together I’ve never done that.  I’m not SO rough with my built kits that they need that extra adhesion

What would these other glues be? Though I don't like the idea of gluing to paint.

I don't intend to be rough with models either but I have moved enough to know that I want them to be able to survive packing, shipping, storage ( sometimes for years) and handeling without need of much if any repair 

[bbowser]

I find myself using liquid cement more these days, it forms a strong bond, dries fast, but you do need to scrape paint/plating.   I also use a lot of Micro-clear on windshields and plated parts.

[jamesG]

1 hour ago, oldscool said:

What he said. I use CA as much as possible because it dries fast and forms a rigid bond. Solvent glue bonds always seem to feel flexible. If you want to check out what I am saying then do this:

Glue the wheels on a model with solvent cement and then do the same to another model using CA. When you sit the model down on a table you can feel how the one glued with CA feels very solid on its wheels. Like the old metal axle kits feel. I hope this makes sense.

I get what you are saying and perhaps I will do some experimenting though on some left overs not a model. 

[jamesG]

13 minutes ago, bbowser said:

I find myself using liquid cement more these days, it forms a strong bond, dries fast, but you do need to scrape paint/plating.   I also use a lot of Micro-clear on windshields and plated parts.

I like micro-clear though I cant find it local anymore.

[StevenGuthmiller]

4 hours ago, jamesG said:

I'm curious as to why you dont like the idea of melting the plastic together.

All you need to do is look at a large portion of old built kits built years ago with tube cement.

I can't count how many times I've encountered parts and bodies that have been completely destroyed due to the use of solvent cements.

If you have ever rebuilt a vintage kit that has had glass glued in with tube cement too heavily, you'll understand exactly why I don't use it.

 

 

 

 

Steve

Edited August 2, 2020 by StevenGuthmiller

[StevenGuthmiller]

4 hours ago, jamesG said:

What would these other glues be?

2 part epoxy will give you just as strong of a bond, (or better) than plastic cement without the hassle of scraping parts.

 

 

Steve

[jamesG]

1 hour ago, StevenGuthmiller said:

All you need to do is look at a large portion of old built kits built years ago with tube cement.

I can't count how many times I've encountered parts and bodies that have been completely destroyed due to the use of solvent cements.

If you have ever rebuilt a vintage kit that has had glass glued in with tube cement too heavily, you'll understand exactly why I don't use it.

 

 

 

 

Steve

I have several built 35+ years ago been packed and moved between more than a couple homes and stored in un air conditioned storage unit for 10 years in florida. All still in great shape. All built with tube glue. Sure I have a couple with glue on the windows and such that isnt a problem with the glue that's a problem with the person that applied it, me. 

I'm rebuilding a 30+ year old vette right now. Yep, got heavy with the glue when originally built and extra care had to be taken when I took it apart just as you should with any glue. 

So, no I guess I dont understand, which is why I asked.

Got to be realistic here, these kits aren't meant to be taken apart that's why they require "glue" and not screws.

 

[jamesG]

2 hours ago, StevenGuthmiller said:

2 part epoxy will give you just as strong of a bond, (or better) than plastic cement without the hassle of scraping parts.

 

 

Steve

This will be fun to put to the test. 

Multiple glues, cements, epoxy etc. On bare plastic vs. Painted then glued plastic. My guess would be that the glue loses bond with the paint or the glue pulls the paint right off the plastic long before glues on bare plastic.

Now, perhaps you want your models to come apart easily in the future. I don't. I don't intend to rebuild them, ever. 

[CabDriver]

Sounds like you’ve got a technique that you’re happy with

[jamesG]

5 hours ago, CabDriver said:

Sounds like you’ve got a technique that you’re happy with

For the most part, yes. However, if someone posts an idea I think might work for me I have no problem adding to my skill set.

[R. Thorne]

Up until a few months ago I used model cement ( Tamiya extra thin mostly) .  Removing the paint had become tiresome, however, even with a number of “specialized” tools.  I now use ca and it is much easier and faster to not have to remove the paint and it appears to hold securely.  I also use Bondene (“glass” held in place with pressure from my finger and bondene applied with a micro brush around the edges) to install windshields (thanks Donn Yost).  I applaud you for keeping an open mind.

[StevenGuthmiller]

9 hours ago, jamesG said:

I have several built 35+ years ago been packed and moved between more than a couple homes and stored in un air conditioned storage unit for 10 years in florida. All still in great shape. All built with tube glue. Sure I have a couple with glue on the windows and such that isnt a problem with the glue that's a problem with the person that applied it, me. 

I'm rebuilding a 30+ year old vette right now. Yep, got heavy with the glue when originally built and extra care had to be taken when I took it apart just as you should with any glue. 

So, no I guess I dont understand, which is why I asked.

Got to be realistic here, these kits aren't meant to be taken apart that's why they require "glue" and not screws.

 

There's no doubt that model cement will create a good bond.

That's not in question.

The question is whether the pros of using it out way the cons.

If you like it, and it's what you're used to, knock yourself out.

My only argument is that there are other products on the market today that are just as good, or better than the old tube cement.

 

Granted, models are not designed to be taken apart, but inevitably, many will be, especially as the hobby declines and companies are producing fewer and fewer kits

I have basically made a career out of restoring old vintage kits, and I have to tell you, if you have never seen horrible "glue rash", "sink marks" or just generally parts that no longer resemble what they originally looked like, you have not seen this side of the hobby.

I have kits in my possession with warped body panels and roofs from heavy glue use, body trim that is no longer repairable, and glass that can never be removed without shredding the body.

These are all very common issues with old built kits, all attributable to model cement.

 

Glues such as 2 part epoxy will give you a very strong bond that in the end might also be difficult to remove should the necessity arise, but at least it will not melt the plastic.

 

I too have kits that are decades old in my  collection that have been moved around often, most assembled using CA glue, and they are still in one piece.

The particular glue that you use is not the silver bullet to longevity.

How the model is handled will determine that, no matter what glue you use.

 

 

 

 

 

Steve

Edited August 2, 2020 by StevenGuthmiller

[jamesG]

22 hours ago, R. Thorne said:

Up until a few months ago I used model cement ( Tamiya extra thin mostly) .  Removing the paint had become tiresome, however, even with a number of “specialized” tools.  I now use ca and it is much easier and faster to not have to remove the paint and it appears to hold securely.  I also use Bondene (“glass” held in place with pressure from my finger and bondene applied with a micro brush around the edges) to install windshields (thanks Donn Yost).  I applaud you for keeping an open mind.

If it works for you, cool. I simply don't  like "gluing" paint to paint as I believe it to be weaker and will remove some if not a good deal of paint when the joint fails.

Yes, scraping is a pain and I avoid applying paint to areas that I know will have to be glued such as where seats go, interior tub to frame, engine block to cylinder head... masking tape is our friend.lol. I also seem to remember from somewhere the use of white glue (Elmer's) as a mask. 

I haven't tried bondene yet. I use either testors, micro crystal clear, or good ole Elmer's for clear parts held in place by... well,  whatever works.

[peteski]

I also avoid gluing painted surfaces (the paint layer in that case is the weakest link).  Whenever possible I simply avoid painting the gluing surfaces. I pre-assemble  model's parts, noting all the areas to be glued, and then mask them before painting (usually using liquid masking medium. Then after painting, I simply pull the masking off revealing bare plastic. That minimizes paint scraping.  Yes, this all involves extra steps, but IMO, well worth it, and it insures a clean build, with strong glue joints.

[jamesG]

18 minutes ago, peteski said:

I also avoid gluing painted surfaces (the paint layer in that case is the weakest link).  Whenever possible I simply avoid painting the gluing surfaces. I pre-assemble  model's parts, noting all the areas to be glued, and then mask them before painting (usually using liquid masking medium. Then after painting, I simply pull the masking off revealing bare plastic. That minimizes paint scraping.  Yes, this all involves extra steps, but IMO, well worth it, and it insures a clean build, with strong glue joints.

What masking medium do you use? I have seen them but never tried them.

[peteski]

4 hours ago, jamesG said:

What masking medium do you use? I have seen them but never tried them.

You are right, there is at least half a dozen various liquid masks geared toward the artist and hobby market.  I have tried (and used) some of them.  But now I use industrial type of masking medium.  I used to work as an electronic technician and we used to use solder mask to keep solder off specific areas of printed circuit boards.   Now I mostly use that type of masking medium for masking.  Here is a link to the TechSpray peelable Wonder Masks: https://www.digikey.com/en/product-highlight/t/techspray/wondermask-px-wondermask-p  
The link is to Digikey Corp. because I buy a lot of electronic components there, but you will likely find this stuff on Amazon or eBay too.

Unfortunately, even the smallest quantities sold are rather large, and I usually end up with half the container going bad, but to me, it is still worth it.  There are 2 types: ammonia-based natural latex, and synthetic-latex.  Natural latex is easier to peel off, but has a shorter usable life. This masking medium is rather thick (more like a paste than liquid). I have in the past used household ammonia to reduce the viscosity of the natural-latex mask.  But I could have also used one of the hobby liquid masks which are usually much less viscous.

[jamesG]

53 minutes ago, peteski said:

You are right, there is at least half a dozen various liquid masks geared toward the artist and hobby market.  I have tried (and used) some of them.  But now I use industrial type of masking medium.  I used to work as an electronic technician and we used to use solder mask to keep solder off specific areas of printed circuit boards.   Now I mostly use that type of masking medium for masking.  Here is a link to the TechSpray peelable Wonder Masks: https://www.digikey.com/en/product-highlight/t/techspray/wondermask-px-wondermask-p  
The link is to Digikey Corp. because I buy a lot of electronic components there, but you will likely find this stuff on Amazon or eBay too.

Unfortunately, even the smallest quantities sold are rather large, and I usually end up with half the container going bad, but to me, it is still worth it.  There are 2 types: ammonia-based natural latex, and synthetic-latex.  Natural latex is easier to peel off, but has a shorter usable life. This masking medium is rather thick (more like a paste than liquid). I have in the past used household ammonia to reduce the viscosity of the natural-latex mask.  But I could have also used one of the hobby liquid masks which are usually much less viscous.

Cool, thanks for the info I'll definitely look into those.