stipping splotches and glue recommendations?

[Packer]

I've been working on one of my first loco projects. I'm at the stripping phase on them and have managed to get a few shells stripped but have a few issues.

1. Are splotches and stains normal when using alcohol? The 2 units that I've gotten done so far have some areas that aren't what I'd hoped they would be:
This F9 has dark areas on the roof and sides that won't come up no matter how hard I scrub. they don't come up with a fingernail either.


Even though the paint is gone, the F7 has an area that almost looks like a mark left over from an SP bloody nose


2. Is it normal for the paint in the grilles and deep areas of the fans to not come up? On the above photos, there are bits of black and silver (only in the grilles of the F7) that won't come up. I've had them in alcohol for over 24 hours and the paint in the grilles refuses to come all the way out.

I'm wondering if I should give these 2 shells more time in the 91% alcohol. There are 2 more shells still soaking that have black paint that refuses to come up so I'm wondering if I should try to find some 100% alcohol or some other paint stripper? I've read that brake fluid will eat these shells, so that's out of the question.

As for the glue recommendations, I have a bunch of white metal castings that I'm going to be applying to these locos. I'm wondering what type of adhesive to use. I think CA would work for a while, but I've had issues with it becoming brittle and losing over time. Would contact cement, walther's goo, elmer's glue-all, amazing goo (is walther's goo based on this?), or white glue give a stronger bond that won't fall apart like CA does?

[peteski]

Vincent,
sometimes if the solvent in the original pint is "hot" enough, it will actually melt some pigment into the plastic. So I wouldn't worry about that. As far as the paint remaining in the crevices (such as the grilles), I would try to get as much out as you can.

I don't recall CA glue becoming brittle with age. Maybe you were using too much accelerator on it or maybe the glue was old?  My preferred adhesive for metal to plastic bonds is CA. Just make sure that the glued surfaces are perfectly clean and degreased. If you want an alternative adhesive, use epoxy (the 5-minute type will work).  Depending on the size and shape of the parts, you can also pin them to the shell (instead of just depending on the glue.  By "pin" I mean to drill small holes in both the part and the body and use short section of brass rod of the diameter that snuggly fits in the hole to hold the part onto the shell.

White glue does not adhere to wither plastic or metal - it is a paper glue.  The other glues  you mention are types of rubber-based adhesives. While they will probably hold the metal part to the plastic, they are flexible.  Not a good idea to use those to permanently affix detail parts.  Unless the parts are long thin flat pieces (like stainless steel grilles). Those expand and contract at a different rate from plastic shell and it is good to use flexible type of cement on those.

[Packer]

Thanks for the info Peteski.

[pnolan48]

I've started to pin every part where it is feasible. I've found it takes less time to drill a tiny hole or two than to hold a part perfectly positioned waiting for glue to set--even CA. And then I never have to worry about breaking it off with a careless touch. I stay away from accelerators as much as possible, as they mound up the glue--yuck! The micro-applicators are very good, and will last a long time when soaked in acetone (for CA) and cleaned up--less CA is more.

[peteski]

As far as CA accelerators go, I couldn't live without them (um, "it").  Either at work or in my hobbies throughout the years I had access to probably more than a dozen of different types and brands of CA accelerators. Many melted styrene and paint, others caused the CA glue to get brittle and bubble up or turn white.  Then I found a perfect accelerator and tossed all the other ones I had in my stash.

The perfect (at least for me) accelerator is the BSI (Bob Smith Industries) brand.  Why ideal?  It has very low odor, it evaporates fairly slowly, it does not attack polistyrene or other plastics (even clear) and it doesn't attack paint.  It is also fairly slow acting (as far as accelerators go), so it doesn't bubble up or discolor the CA glue joints.  It also makes CA glue less brittle than other brands.  Highly recommended.

As far as application goes, when we are talking about attaching small pieces to a body, NEVER SPRAY ACCELERATOR ON THE MODEL!  That is just silly.  That wastes a huge amounts of the accelerator and makes it go all over the model when all you want is to harden a glue joint probably the size of a pinhead.   As Pete mentioned, small applicators (such as Microbrush) are perfect for the job.  I usually use the white Microbrush.  I dip the end in the accelerator then rub the tip agains my fingernail (to remove some of the liqid as even with the small Microbrush head I find that it holds too much liquid). then I touch the brush head close to where the glue joint is (not directly against the liquid CA glue). The accelerator will spread out slightly on the model's surface until it comes in contact with the liquid CA glue. That starts the  reaction and few seconds later the glue joint is set. Once the remaining accelerator dries up, there should not be any visible traces of it.

BTW, the thicker the glue is, the longer it takes for it to respond to the accelerator.  Try the BLI brand and you will most likely never go back to any other brands.  No, I'm not getting paid for this "ad" - I just really think that BSI accelerator ROCKS!  Their glues aren't bad either and most hobby shops stock BSI.

[pnolan48]

I have about 20 micro applicators, 10 each of the small and medium. Since I'm working with cast resin, brass, and styrene in building ships, I've developed a system when working with CA. In one shot glass, unused or clean applicators are brush up. In a second shot glass, used applicators are brush down in a small amount of acetone. I've found that applicators are good for only a minute or so, until the CA hardens on them. After a few hours, I might have ten applicators soaking in the acetone. I then use a paper towel to remove the softened CA from the applicators. It's a sticky gel by this point, and I occasionally pull off the tip, whereupon I discard the stalk. Shot glasses are bottom heavy for their size. Any acetone left is dumped into a closed container--a juice glass with a clear plastic cup jammed on top, and used to clean paint brushes. Acetone is my preferred strong solvent, as it is not particularly toxic, and works for every hobby paint. Not for thinning, but for cleaning.

When gluing, I usually make a small puddle of CA on a small piece of scrap styrene (I have loads of that), and use the applicator to pick up a small amount for gluing. I use two different thicknesses of CA: medium for tacking pieces together, and super-thin for bonding long pieces together. For a long joint, such as the gunwhale to hull joint that can be anywhere between 9 and 36 inches, I will tack it in several places, orient the joint nearly vertical, and apply a drop of super-thin at the top. It's kind of cool to watch the glue race down the joint and bond nearly instantaneously. I buy the medium at the local dollar store for $0.50 a 0.25 oz tube, and the super thin at my LHS for about $3 for an oz. The super thin has lasted two years now, and I'm less than half way through it. As Peteski mentioned, CA does get old; I might add that the thicker mixtures get older quicker than the thin ones.

I do use the BSI accelerator, and the bottle must be 10 years old and still half full. Since CA sets with moisture, just blowing on a joint is my most often used accelerator. Hmm, I wonder if beer-breath works better than coffee-breath?

[peteski]

Unlike Peter Nolan, I only use Microbrushes for applying the accelerator.  For applying the glue itself I use precision applicators I made myself from sawing needles. From Pete's description I woudl find the constant cleaning too tedious. Here is a photo of the various ones I made (along with couple of Microbrushes):



They usually do not clog up during my work session and if some glue eventually hardens in the fork, that can easily be chipped off using a hobby knife blade (needles are harder than the knife blade so they easily survive the cleaning).

[Chris333]

SWEET!   

[Packer]

So is the accelerator actually necessary? I've never used it.

Peter, so it looks like I should be using thin hobby quality CA for striker plates, doors, and pilot plows on the F-unit project of mine, but for grabs and such use medium CA? Looks like the non-branded CA I get at walmart is okay too.

Peteski, I like the idea of yours using the needles to apply CA. How did you make the handles for them?

[peteski]

Vincent,
the applicator handles are simply 1/8" clear acrylic rod (simply because I had bunch of it handy). But you can use wooden dowels, styrene rod or even plastic "sprue" frames leftover from plastic model kits.  Just drill the end and glue the needle in using....... CA and accelerator.

Also note that the 3rd item from the bottom is simply a piece of stainless steel straight pin with the head cut off and the end flattened. That is for applying very small amounts of CA glue (yes, it does get used from time to time).

CA sets when exposed to moisture in the air so accelerator is not needed in most case. But accelerator makes the assembly process so much quicker!  If you are interested in more of CA's properties see http://en.wikipedia.org/wiki/Cyanoacrylate

[pnolan48]

I find the cleaning not all that onerous, as I use one until the CA builds up and makes it stiff, then dunk it into the acetone. At the end of the day (and I am working 8 hours a day on the ships), it takes about three minutes to clean up whatever I've used.

Like Peteski, I have a number of special applicators, usually just straight pins. I found some about four inches long 30 years ago and they work just fine. My tools are nowhere near as refined--I've just ground some of the tips down for a little larger area than the head of a pin.