r.m.s FAQ - part 4 of 16 (29023)
Don_S...@transarc.com
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Part 4
** General how-to questions
**
** This sections covers frequently asked questions regarding construction
** techniques that can be answered in a few paragraphs. Questions with
** longer answers have their own FAQ section. Most of these questions
** are fairly general, although some very specific questions are asked so
** frequently I've included them here too.
[Q] How do I remove "chrome" from plated parts?
[Q] How do I remove paint from a model?
[A] sch...@transarc.com (Don Schmitz 8/95)
The "chrome" plating on model parts is extremely fragile, and most
hobby paints aren't much tougher. There are hobby specific paint removers,
but many household cleaners will remove both. Find a plastic container
with a lid and soak the part or complete model in one of the following,
listed in roughly increasing order of chemical nastiness:
Castrol Super Clean (hand cleaner ? - buy at auto stores),
Fantastic, Formula 409, Pinesol (not lemon scented),
chlorine bleach (works good on chrome, maybe not paint),
EZ-Off oven cleaner,
common dot3 brake fluid (more toxic - not good to wash down the drain -
but good for long dry paint).
The time to soak varies with harshness of the chemical, from a few
minutes to a few days. Chrome plating should just disappear, you'll
likely have to scrub the paint off with an old toothbrush, especially
from the nooks and crannies. Some cleaners are reported to etch or
embrittle plastic, so keep the exposure brief and flush with water
afterwards. A downside to the harsher, faster acting chemicals is
that they tend to remove putty as well.
One thing *not* to use is standard methyl-ethyl ketone based paint
removers - this stuff will disolve styrene very quickly. Lemon scented
Pinesol has also been reported to soften plastic.
Finally, the nastier of these cleaners - especially the EZ-OFf and bleach -
can cause burns to the skin, eyes and nose, and who knows what else.
Use common sense and lots of ventilation (common sense includes
wearing safety goggles, rubber gloves, and a respirator when using this
sort of stuff).
[Q] How can I get a chrome finish onto a part?
[A] sch...@transarc.com (Don Schmitz 8/95)
The "chrome" finish on model parts is really vacuum deposited
aluminum, and requires specialized (read expensive) equipment to do -
it is not a do-it-yourself sort of project. There are aftermarket
companies that do this sort of work - you send them carefully polished
plastic parts and they chrome plate them. It is somewhat expensive -
order $20 for a handful of parts. Look for ads for these places in
the modeling magazines. "Chrome Tech USA" is one that comes to mind.
If you are trully obsessive, the best chrome finishes are achieved by
casting/fabricating the parts in brass and having them nickle plated
by a bumper shop or jewler, or casting directly in silver. Needless
to say, this is beyond the scope of this FAQ.
[Q] How do I make my own dry transfers?
[A] sch...@transarc.com (Don Schmitz 8/95)
Dry transfers - graphics using "rub on letter" technology, are much
easier to make (and afford) than custom decals. Here is an answer
I sent to someone in the recent past:
I found the magazine article I mentioned - it was the December '94 issue
of "Scale Auto Enthusiast", issue #94.
The process they describe is to produce original black on white
artwork using a good quality printer/copier. You produce a positive -
ie. the black is the part you want to become the marking. The print
shop will expect a true size image to fill an 8 x 10 inch sheet. The
article suggests drawing/producing the artwork at 2 or 3 times actual
size, and then reducing it with a good quality copier to smooth out
minor glitches (eg. quantization staircases). Mount the on-paper
atwork on a sheet of white posterboard for strength, using 3M spray
adhesive. Leave 3/8ths of an inch between items on the sheet, and a
similar border around the edge of the sheet. Just about any color ink
can be matched, but you pay more if it is a custom mix.
Typical costs were given as $8 to produce a negative, and $25 per sheet.
It didn't mention if there was a quantity break for producing more
than 1 sheet at the same time - most modelers have a hard time filling
up 1 sheet.
The claim was most any commercial print shop can make these (they are
used by architects to produce repetitive details on drawings of
buildings, and by advertising shops to mock-up new product packaging).
The author [Pat Covert] did give the name/address of one shop he has
used that will do mailorder work:
Lithoplate and Negative, Inc
2429 3rd Avenue South
Birmingham, AL 35233
205-251-7291
The result is supposed to be similar to "letraset" - I'd guess its not
real rugged. An electrical engineer friend of mine used to use
letraset for panel markings on one-off medical equipment he built - he
always used a clear satin lacquer finish over the letraset to protect
it.
Another outfit with a recommendation is:
Exact Decals and Details
340 Mansfield Ave.
Pittsburgh, PA 15220
(Think they advertize regularly in FSM).
[Q] Why do my decals have ugly silvery borders?
[A] sch...@transarc.com (Don Schmitz 8/95)
Decals work best on a smooth glossy surface. If you put a decal on
top of a flat painted surface, you get "silvering" - the decal film
can't conform to the rough surface of the flat paint and so you get
air bubbles under the film producing the frosted look. Assuming you
really wanted the flat finish, the solution is to use gloss paint,
apply the decals, and then overcoat everything with a clear flat
finish like Testor's Dullcote. Its quite common that you can't find
the military colors you need in a gloss paint - so the procedure is to
paint with flats, overcoat with a clear gloss finish like Testor's
GlossCote, apply the decals, and finally apply the DullCote over the
whole works.
----------------------------------------------------------------------
Note: the following information was extracted from the previous
version of the FAQ compiled by Urban Fredriksson. I've edited out a
few repetitive answers in the interest of space, and added the [Q] and
[A] style markers that let me generate the table-of-contents section
from the source. Many thanks to Urban for putting this together the
first time around.
----------------------------------------------------------------------
[Q] What are the basic techniques of painting models?
[A] u...@icl.se (Urban Fredriksson)
Paint difficult areas first - All kits tell you to paint the smaller parts
before assembly. I also paint difficult to reach areas while the model is
unassembled. In fact, I ALWAYS paint the wings of the plane before I attach
them to the fuselage. this way I can give each the attention they deserve.
Once assembled, a lower wing will always receive a second rate paint job.
Don't forget to prime the interior of the fuselage black when the halves are
unattached. this will brevent the shiny coloured plastic from spoiling the
effect of the model.
...
I almost exclusively use Polly-S and Tamiya acrylics.
To use them with an airbrush, I thin them with a mixture of
50% water, 50% ethanol/methanol and a very small amount of
dishwashing detergent.
I have the thinning mixture in small glass bottles with drippers.
To get the proper amount of detergent:
- put a drop of detergent in the bottle
- fill it with water, shake and empty
- repeat stage 2 two times
- fill up with 50% water and 50% ethanol
Some people have successfully used windowcleaner instead of this
mixture
Usually you have to add 40-60% thinning mixture to the paint. It
should give a very thin layer, so expect to put on several.
To decrease the drying time, you can use a microwave oven. Put a
glass of water in the oven to protect it, then put the model in
for maybe 30 seconds at half power. In this way I've managed to
put on 5 layers of paint in 20 minutes.
I have a few tins of enamels, but I use them almost only for
....
[A] boe...@sctc.com (Earl Boebert)
Let me add a couple of tips from my days of supplanting military pay
by painting HO brass locomotives and the occasional custom-built
plastic model:
1. Surface preparation is essential; in the case of plastics, making
sure that all the parts have been washed to remove the parting agent.
Avoid fingerprints. Handle parts with tweezers or wear "finger cots,"
which are sold in office supply stores and look like miniature
condoms; these keep your finger oils off of the surface but still
enable you to feel what you're doing. (followups to alt.sex.plastic,
please. :-))
2. Look for the thinnest masking tape you can find; the stuff sold in
artist's supply stores is often much thinner and with less "tack" than
the automotive/hardware kind.
3. Cut your own strips, using a scalpel and a steel ruler. I would
lay the tape out onto a glass plate and cut strips about 3/16" wide.
This makes for much cleaner lines, as the rough edge and adhesive
"bleed" from the machine-cut rolls is eliminated. If you need more
width, add a band of plain paper or (as the previous poster mentioned)
aluminium foil.
4. As mentioned, remove tape as soon as the paint has "surface set."
Learn what this time is for the paint you are using by experiment.
5. As with anything that mixes craft and technology, the really
spectacular results are obtained through a deep understanding of the
medium you are working in. What this means is that you find things
like brands of paint and tape that work and you stick with them, so
that each job becomes less and less a voyage of discovery and
experiment.
Hope this helps.
Earl
[Q] I understand pastels can be used to achieve subtle colour variations
[Q] especially for weathering, what kind of pastel should I use?
[A] u...@icl.se (Urban Fredriksson)
Use chalk pastels, not use oil-base pastels. Most people use pastels
for weathering and highlighting areas on models. I would recommend
obtaining a set of shades of gray, and a set of earth tones. I
obtained a set of 12 of each ranging from very light to very dark at
a craft store for about $4.50 for each set. You can also obtain
many individual colour, like shades of green. I've used these for
creating the line camouflage on some German aircraft used in Africa.
[Q] How do I apply pastels
[A] u...@icl.se (Urban Fredriksson)
There are several ways to apply pastels. Here are some tips:
1) Make sure the model has a matte finish. This can either be the
bare matte paint, or if the paint is gloss, a matte overcoat.
2) Use fine sandpaper or emery boards to make some chalk dust. At
this point different coloured pastels can be mixed.
3) To apply the pastel, use a paintbrush, preferably with somewhat
firm, yet soft bristles. Alternately, there are cardboard pencil
like applicators that can be obtained at craft stores. Q-tips
also make a good applicator, as well as pieces of felt. A very
good applicator can be obtained from a cassette head cleaning kit.
These kits usually have a small handle and pieces of felt used to
clean the head of a cassette player.
4) Don't worry if you apply too much, a damp cloth will clean it
right off.
5) Use of a sealer coat is optional. Unless you will be handling the
model much, one is not necessary, and looks better.
[Q] There are so many fillers today, and I hear about so many other things
[Q] and techniques people use for filler. What should I use?
[A] u...@icl.se (Urban Fredriksson)
The statement that there are many fillers today is quite accurate. As
with everything in modeling, there is no one answer as to which to
use. It partly depends on what it is you want to fill. Is it a small
nick or sinkhole in the model, is it a large seam, or did you do a
conversion and need to fill a large area? The answer to this question
partly determines what you should use. Also it also boils down to a
matter of personal preference. The best way to answer is to tell what
is available, give some of the characteristics of each, and some
recommendations as to the situations that they work best in. There
are those products that are intended as model fillers, those that are
fillers for other things, and others. Let's take a look at each type.
Here is a partial listing of some of the available putties and other
fillers
Model putties:
Squadron Green Putty
Dr. Microtools Supreme Model Putty (red putty)
Testor Contour Putty
Other model fillers:
Mr. Surfacer
Non-model specific filler putties:
Bondo
Other:
2-part epoxy putty
thin superglue
gap filling superglue
Lets look at each kind, and some of their characteristics.
Model Putties
The most commonly used products are the model specific filler putties.
I personally don't recommend the Testor Contour Putty. It was the
first that I ever used many years ago. Maybe things have changed with
it since, but it shrank quite a bit, and was not based on a solvent
that bonded to the plastic. It was also somewhat brittle and tended
to flake off of the model if even slightly flexed.
Dr. Microtools and Squadron putties are quite similar in performance.
They both are based on a solvent, toluene if I am not mistaken, thus
they bond with the plastic. They fill gaps well and are easy to sand.
They do have some disadvantages though. They both shrink if large
amounts of filling are needed, like if you are doing a conversion and
have very large areas to fill. They should be applied in thin layers
when you have large areas to fill. This helps some in solving the
shrinkage problem, but not completely. It also prevents the problem
of too much solvent damaging the plastic (I'm almost ashamed to admit
this one, but back when I was in high school beginning modeling, I
decided Squadron Green Putty would be good to fix some weights into
the nose of an F-14. Well, the nose radome collapsed from too much
solvent). Another problem is that when sanded, these putties
invariably will have small pinhole bubbles in them.
Other model fillers
One of the best products to come around in a long time for the modeler
is a product caller Mr. Surfacer produced by Gunze Sangyo. In my
opinion, and in the opinion of several of my fellow modelers in our
local club, this is almost a miracle product. "What is Mr. Surfacer?"
you may ask. Well, I guess the best way to describe it is that it is
a thin filler, almost the consistency of paint. It is the best filler
for small gaps, seams, scratches and the like. It can be applied with
a paint brush, toothpick, or whatever you like. It dries fairly fast.
It dries without bubbles and is very smooth, and sands very well. It
comes in bottles in two grades, #500 (a thicker variety) and #1000.
It also makes a GREAT primer. It can be thinned with Gunze Sangyo
thinner, or as I have used, Dio Sol, and airbrushed. If you don't
have an airbrush, it also comes in a spray can variety. Using it as a
primer the first time (or any time for that matter) is an interesting
experience. Unlike other paints, you spray the Mr. Surfacer on fairly
thick. It will look like you have filled every scribed line and
obscured every detail on the model, but when you put it aside, go
away, let it dry and come back, it will "suck down" tight and every
detail will show, and any small sanding scratches or the like will be
gone. This brings me to the only disadvantages. It isn't intended
for large gaps, but if you layer it, it can be used even for large
areas needing filling. It also, since it is so thin compared to
putties, shrinks much more. However it's lack of bubbles and quicker
drying time more than make up for this.
Super glues
Super glues also make very good gap fillers. Thin superglues work
well for small gaps and scratches. For gaps along seams, put a drop
of superglue on a sheet of wax paper, and use a #11 hobby knife blade
as the applicator. Put the tip of the blade in the superglue, and
run the point along the seam like you were cutting, but don't apply
too much pressure. For larger gaps, you can also use superglue
combined with baking soda. Put some baking soda in the gap, and apply
the superglue to the baking soda. The baking soda will add some bulk
giving more filling capacity, and the baking soda acts as an
accelerator for the superglue.
Thick gel type superglues work very well for larger gaps. I usually
use a toothpick, needle, or #11 blade as the applicator.
As fillers, superglues have advantages over hobby fillers in that they
don't have bubbles when they set. They also shrink very little if
any. They also set very rapidly, so can be sanded much sooner. Their
primary disadvantage is that they are harder than plastic, so if you
are using building a model that uses a particularly soft styrene, the
plastic and superglue may not sand evenly if you don't take care to
make sure that they do. Probably the best way to guarantee this is
to use a sanding block. Also, don't spread the superglue with your
finger. For more information on superglues, refer to the section
covering superglues in the glues section of this FAQ.
Non model specific fillers
There are a number of fillers that are not intended for models, but
can be used. Most of these are auto body fillers. There are many
different ones available. I have not tried any, but others have and
have had good luck. One that was recommended was Bondo. It is
solvent based, and will bond to the plastic. It also gets harder the
longer it sets. It gets very hard, and can be difficult to sand if
left to set too long.
Epoxies
Two part epoxies can also be used for filler. Either the thin,
molasses consistency ones or the putties can be used. There are
many different epoxies, the long set varieties all the way to the
5 minute varieties. In general, the shorter the set time, the softer
the epoxy when it is set. Some of these are even softer than the
plastic. Also, most of the putties are not very hard setting either.
One of the harder setting epoxies that I know of is JB Weld. It's not
too hard to sand, but it is harder than plastic. The advantages of
epoxies are that they do not shrink. They do not attack the plastic.
Their disadvantage stems from this, in that they do not really bond
with the plastic like solvent based fillers. IMHO, epoxies are the
least desirable for most filling applications.
...
Tipp-Ex for small gaps. Soft but paints well.
Milliput for larger jobs. Can be built up rather thickly, and
softened during application by mixing in small amounts of water.
Home made putty made from plastic shavings and Ethylacetate.
Unfortunately dries very quickly, so you have to make it as you
use it.
[Q] What glue should I use to glue plastic together?
[A] u...@icl.se (Urban Fredriksson)
That depends on the plastic being used. Lets start with the most
common used in modeling, polystyrene.
Gluing polystyrene to polystyrene
There are 2 ways to approach gluing styrene to styrene. One is to
actually weld the parts together and the other is to attach the parts
through an adhesive. Which way should you use? It depends. Lets look
at ways to accomplish each, and their advantages and disadvantages.
To weld the plastic, one could actually try welding, but that isn't
practical. When I mention welding the parts, I mean using a solvent to
dissolve the surfaces to be joined, and letting the solvent evaporate.
Most common model cements aren't cements, but are solvents, and take this
approach. These liquid cements are either aromatic or alphatic solvents,
ketones or chlorinated hydrocarbons. Here is a list of chemicals that
are solvents of styrene and some of their characteristics.
evaporation odours cost
- Acetone 1
- Benzaldehyde
- Benzyl alcohol
- Chloroform strong
- Dichloromethane
- Ethylacetate
- Ethyl isopropyl ketone expensive
- n-Butanone strong
(methyl ethyl ketone,
MEK)
- Toluene 5 strong
- Trichloroethane
- Xylene 5 strong
1 very, very quickly
5 slow
Commercial liquid cements, what they are made from
Testors MEK
Tenax 7R Trichloroethane (?)
Floquil DioSol Toluene/Xylene (ok, this isn't sold as cement, but it
can be used as liquid cement)
Editorial Warning:
A reader who should know pointed out that many of the chemicals listed
above are extremely toxic and/or carcinogenic. It is unlikely that
any hobbyist working in their basement/kitchen can hope to use these
safely. Given the variety of commercial products available, at quite
reasonable prices at the local hobby/toy store, it seems silly for
anyone to use something like chloroform to glue their models together.
Please use common sense and lots of ventilation. - Don Schmitz.
[Q] How do I used liquid cement?
[A] u...@icl.se (Urban Fredriksson)
For most seams, hold the parts together, not too tightly, and use a
brush or needle applicator to apply to the joint, allowing capillary
action to pull the cement along. Once cement is applied, press the
parts together tightly and clamp (rubber bands work well for the
fuselage of aircraft). If the seam fits well, the little molten
glue/plastic combination that oozes out will fill the gap and can be
sanded when the cement has dried. Little filler should be needed.
[Q] Which cement should I use?
[A] u...@icl.se (Urban Fredriksson)
That is a matter of personal taste. I have personal experience with
Testors, Tenax, and diosol. I like Testors very much for most
applications. I usually let it set up overnight before removing
clamps and sanding. I like to wait longer if I am not too eager to
work on the kit. It produces a very solid seam. Diosol is very
similar.
Tenax 7R sets extremely fast. With Testors, I sometimes apply to flat
surfaces then mate them. This is impossible with Tenax. You have to
use capillary action. The joint is dry enough to sand within half an
hour, shorter for small joints. It welds the parts, but because of
the speed of evaporation, I have had bubbles for surfaces that didn't
mate very well. It is fantastic for surfaces that mate very well.
Ethylacetate is very thin giving it good capillary action
capabilities. It evaporates rapidly, is reportedly less harmful than
those containing Tolouene and Xylene, and is cheaper.
[Q] With the proliferation of vinyl figures by companies such as Horizon,
[Q] and small vinyl figures, what should I use to glue the parts?
[A] u...@icl.se (Urban Fredriksson)
One suggestion is to try cyanoacrylate, or superglue.
[Q] Of what kind of plastic are soft drink bottles made?
[A] u...@icl.se (Urban Fredriksson)
Soft drink bottles are made of PETE plastic. PETE is an acronym for:
PolyEthylene Terephthalate Ester
or more commonly, polyester. Apparently, Kodak makes about 80% of the
plastic soda bottles used in the U.S. Additionally, DuPont and
Hoechst-Celanese also manufacture polyester. A big reason is that
Kodak, DuPont, Himont, and Amoco are all major manufacturers of
purified terephthalic acid, one of the raw materials used in making
polyester.
[Q] Are their solvent type cements that can be used to join PETE plastic
[Q] like there are for styrene?
[A] u...@icl.se (Urban Fredriksson)
Yes, there are, but they are pretty nasty substances. The known
solvents for PETE are:
phenol
o-chlorophenol
dichloroacetic acid
trifluoroacetic acid
hexafluoroisopropanol
pentafluorophenol
methylene chloride/hexafluoroisopropanol
tetrachloroethane/phenol 1:1
and various combinations of other chlorinated alkanes with
halophenols
One would generally not like to use these at home.
[Q] What can I use then to join PETE? Epoxy and tube model cement just
[Q] lift right off.
[A] u...@icl.se (Urban Fredriksson)
Probably the best would be to use superglue. Some use PETE as wing-
tip protectors for flying model airplanes. They recommend roughening
the plastic with 100 grit sandpaper and using gel type gap filling
superglue to attach it.
Hot melt adhesives, such as those used in glue guns, is also a
possibility for the adhesive, but superglue is probably better in most
modeling applications.
[Q] What do I use to glue together dissimilar materials?
[A] u...@icl.se (Urban Fredriksson)
There is not one pat answer to this. 2 part epoxies and
cyanoacrolates are probably the best. And depending on the
application, one could also use contact cement.
[Q] What do I use to glue together to metal parts?
[A] u...@icl.se (Urban Fredriksson)
This is particularly important to figure builders, since many figures
and parts are made from white metal. One of the oldest and probably
best ways is to join metal parts is by soldering them. If you don't
want to learn to solder, then adhesives can be used. If the parts mate
very snugly, particularly 2 flat surfaces, superglue works very well.
For surfaces that do not mate quite as well, gap filling thick
superglue is one option. 2 part epoxy is also something that can be
used.
[Q] What should I use to glue wood to wood?
[A] u...@icl.se (Urban Fredriksson)
The best glue for wood is Alphatic resin, carpenters glue. It
produces a joint that is stronger than the wood itself usually.
[In the US, Elmers is a common brand - the yellow stuff sold in
hardware stores, *not* the white glue sold most everywhere else.]
[Q] What should I use to glue wood to styrene?
[A] u...@icl.se (Urban Fredriksson)
There are several options. Some suggestions are:
1) You could try using superglue with an accelerator. This would
probably have to be thick superglue, unless you are using a very
dense wood. Thin superglue would tend to absorbed by the wood like
a sponge.
2) 2-part epoxy would probably be best, since it works well at
joining dissimilar materials.
3) If the styrene is thick enough to withstand heat, hot glue may
work well.
[A] jke...@ford.com (Jim Kerns)
Gluing Styrene to wood or paper is a pretty typical thing to do when
assembling flying model rockets. Tube type plactic cement works fine -
that's what Estes recommends. CyA also works. Glue soaking into the wood
really isn't much of a problem. I use thin CyA to attach balsa fins to
paper body tubes all the time - hold the parts in place and add several
drops of CyA. It does soak into the end grain of the balsa and the paper
tube so you have to use several drops instead of just one drop like you
might between nonporous surfaces, but it works quite well.
[Q] It seems that the super glue that I am using glues my fingers together
[Q] better than the parts, why?
[A] u...@icl.se (Urban Fredriksson)
This is quite natural, considering why cyanoacrylate was developed.
It was developed for doctors as a way to seal wounds without sutures
during Viet Nam. In the field, with the many wounds, if a way existed
to quickly seal a wound with out stitches, more people could be saved.
So, biological things such as fingers are joined very well by CA.
[Anyone know if this is true? Seem to recall this being discounted
as an ubran legend - at least as far as CA being developed
intentionally for this purpose. Not to say there weren't some
enterprizing field surgeons who used it this way...]