How to safely strip a Skytop Models resin shell?

[cgw]

I use a north coast hobbies sandblasting booth,  220 grit al oxide with 60psi to remove paint and to prep the surface for new paint.  Never had any issues with removing any manufactures paint. With lower pressure setting I can remove road numbers for renumbering  the units.  You can save yourself a lot of bucks by getting the cheapest sandblasting booth from harbor freight. 

[motofavorite]

So what's a good air eraser, and what's a great medium to use?

Same question! And I wonder whether there are other considerations. Can I scavenge the spent media with a vacuum cleaner? Is it worth trying to recover and reuse the media?

[peteski]

Heck - less than 2 bottles of Scalecoat Wash Away.

Hurray, I need a new tool!

Sure, but it is *REALLY* messy!  Nobody seems to mention that part. If you blast in out the open, the blasting media will go all over the place. Not only it will be a mess - you also won't be able to collect and reuse the media.  You really need to build some sort of enclosure to contain the blasting media and to be able to reclaim and reuse it.

[Dirk Jan Blikkendaal]

Sound advice from Bill and John....... use the cheap Harbor Freight Air Eraser, using 50-60 psi pressure and 2 moisture traps (one on the compressor and the other one comes with the AIr Eraser.

Overhere in The Netherlands I bought the same blasting unit from a different supplier with one extra bag/box of ALU oxide about 3 years ago for about $ 25....... still using the same ALU oxide and I use this thing a lot.
I also bought a large (about 45 x 60 x 45 cm) see-through storage box (see picture). Made 2 round holes and covered these inside and outside with plastic foam.
Make a X cut in the foam to put your hands through.

This way you keep the ALU oxide dry (absolutely necessary), the stuff stays inside the box and does not fly EVERYWHERE (saves a lot of clean up time) and you can easily collect and re-use it....... over and over again.
You might have some clogging of the nozzle sometimes.......... simply unscrew the nozzle inside the box and push steel wire (0,3 mm) through the nozzle hole.
Make it a long wire (20 cm) to easily find it..... The storage box gets a bit foggy after long use.... This clogging problem vanishes over time as the nozzle exit wears out a bit with much use.

Clean your model in soapy water to remove the ALU oxide sticking to it.....

I use the Air Eraser to give my Shapeways prints a extra cleaning (after soaking in Bestine/Naphta), to remove paint from (older) models and to roughen the surface of etched model kits. The paint adheres much better this way.  I also cleaned older tarnished/painted brass models this way, works perfect, especially on screen grills.
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[Spades]

The storage box gets a bit foggy after long use....

Humans  love to point the bead blaster directly at their face, object and glass.  Before first use of the box.  Tape the inside of the box, where in the future you might like a viewing port.  As the surrounding area becomes to cloudy, just peel the tape and you have a spanking new clear view.

[nickelplate759]

I assumed  @Dirk Jan Blikkendaal  was referring to dust floating in the box, rather than the box itself being etched.  Those plastic tubs are usually cloudy even when new.

I think to address floating dust one would need an air filter and forced air circulation, at which point we are well past the "quick-and-cheap" variety of box.

[reinhardtjh]

I assumed  @Dirk Jan Blikkendaal  was referring to dust floating in the box, rather than the box itself being etched.  Those plastic tubs are usually cloudy even when new.

I think to address floating dust one would need an air filter and forced air circulation, at which point we are well past the "quick-and-cheap" variety of box.

Maybe not totally quick and cheap, but still pretty quick and cheap is @Lemosteam 's version
  https://www.therailwire.net/forum/index.php?topic=50417.msg714787#msg714787

[Lemosteam]

Maybe not totally quick and cheap, but still pretty quick and cheap is @Lemosteam 's version
  https://www.therailwire.net/forum/index.php?topic=50417.msg714787#msg714787

Thanks John, I was looking for that!

[Doc Frankenfield]

I assume we are speaking of resin print, not cast resin? ammonia can strip mos paint and some success can be had with "Awesome" cleaner.
Cast resin should be resistant to just about everything. At east Alumilite resin is, not sure about the smooth-on stuff.

[Doc Frankenfield]

I assume we are speaking of resin print, not cast resin? ammonia can strip mos paint and some success can be had with "Awesome" cleaner.
Cast resin should be resistant to just about everything. At east Alumilite resin is, not sure about the smooth-on stuff.

[nickelplate759]

I assume we are speaking of resin print, not cast resin? ammonia can strip mos paint and some success can be had with "Awesome" cleaner.
Cast resin should be resistant to just about everything. At east Alumilite resin is, not sure about the smooth-on stuff.

No, it's cast resin.  @skytop35 made and sold exquisite cast resin shells until fairly recently (often from beautifully kitbashed masters), and I'm luck enough to have bought a few.   I'm going to follow his advice and not use chemicals to strip it.

[peteski]

I assume we are speaking of resin print, not cast resin? ammonia can strip mos paint and some success can be had with "Awesome" cleaner.
Cast resin should be resistant to just about everything. At east Alumilite resin is, not sure about the smooth-on stuff.

Ammonia only works on water-based acrylic or latex paints.

"Stinky" paints need other strippers.  Lye-based strippers LA tatally Awesome cleaner, Castrol Super Clean or the generic versions, or the original formula Easy-Off Oven Cleaner) work on some of them (usualy enamels).  Then of course are the alcohol or glycol based strippers that work on lacquers and some enamels).

Tru-Color paints are "stinky" paints. Either lacquers or maybe even inks (like Accu-Paints supposedly were).

[Doc Frankenfield]

you do realize that chemically, the products you mention are simply strong versions of ammonia? i.e. ammonia is a weaker base, thus less aggressive to resin.  worth an initial try, especially if he paint is not bonded well to the engineered resin.
I used to use ammonia to strip older enamel paints like from the old HO slot cars with great success, and yes the newer detail paints are much harder to strip.

Ammonia only works on water-based acrylic or latex paints.

"Stinky" paints need other strippers.  Lye-based strippers LA tatally Awesome cleaner, Castrol Super Clean or the generic versions, or the original formula Easy-Off Oven Cleaner) work on some of them (usualy enamels).  Then of course are the alcohol or glycol based strippers that work on lacquers and some enamels).

Tru-Color paints are "stinky" paints. Either lacquers or maybe even inks (like Accu-Paints supposedly were).

[peteski]

you do realize that chemically, the products you mention are simply strong versions of ammonia? i.e. ammonia is a weaker base, thus less aggressive to resin.  worth an initial try, especially if he paint is not bonded well to the engineered resin.
I used to use ammonia to strip older enamel paints like from the old HO slot cars with great success, and yes the newer detail paints are much harder to strip.

I'm not a chemist, but I know that strong Lye solution works well for stripping many paints while being safe for polyurethane resin, polystyrene and ABS.  Lye based strippers have been used by modeler for many many years (me included).  That's why I recommended it.