Prepping model for paint by cleaning with Simple Green. Ooops!

[Mustang JBB]

Before I do any painting, I always wash my models to rid them of finger oils etc so that the paint or primer will stick better.  I usually use dawn dish soap or diluted Simple Green.  The SG does a great job at getting rid of mold release agents and cleaning bare plastic or resin. It also rinses away much easier, but is definitely harsher than Dawn. 

 

My latest model is a 1/32 Hasegawa Bf-109 F-2. I painted the cockpit using Vallejo and Tamiya paints, using Vallejo dullcote to seal everything in.  For some dumb reason, I sprayed full strength SG on the assembled model to clean it before priming.  The spray bottle of SG you buy at the store is still very concentrated and can be diluted further.  As the model dried, I began to see that the SG had attacked the Vallejo dullcote and gave it a "frosted" look.  Not completely white, but enough to change the finish and change the the look of the cockpit. I was able to rescue the cockpit using oil based filters and washes, which darkened it back up, but it s not as pretty as the original cockpit.  I was soooooo proud of the original.

 

I don't know if this happened because I did not dilute the SG before using, or because SG and Vallejo(polyurethane) are not compatible at all.  Most likely the later.  I have never had problems using SG and enamels or lacquers.  Can't remember if I have ever used it over Tamiya or other acrylics.  Anyway... Just be careful if you use SG and acrylics of any kind.  i will be using Sg only to clean bare plastic or resin from now on.

 

Obviously Dawn dish soap is very gentle and works on all paints without harm.  It just takes more rinsing.  Also, if you have a water softener in your home, that can leave some soap residue on the models.  Think of how you feel in the shower.  I always do a final rinse with filtered water from the RO system in the kitchen, kinda like a spot free rinse at the car wash.

 

Happy modeling!

[1to1scale]

Your story I guess makes sense. One thing I know is that Simple Green and Purple Power are Caustic Alkali based cleaners, enough so, that they ate away enough metal from my aluminum pistons I was cleaning them with that I had to scrap them and buy another $700 set of pistons for my Dart's engine. I learned a lesson about using these to clean parts with.

 

I use Black Magic Bleach White and Dish Soap to clean resin parts before painting. But I never use anything harsh after paint.   

[BiggTim]

Like I suggested in the other similar thread, I prefer 91% isopropyl alcohol, because it evaporates and does not require water to remove it. I can wipe down or scrub the parts with a toothbrush, set them aside, and they are ready to paint in a matter of minutes. I don't like Lacquer thinner because of the fumes, and it will eat regular plastic, but not resin.

 

Tim

[Bstarr3]

I also wipe down the model with 91% IPA before paint. I only do this on the assembled plane before starting the exterior coat. I leave interior and fiddly bits unwashed before paint

[Mustang JBB]

Like I suggested in the other similar thread, I prefer 91% isopropyl alcohol, because it evaporates and does not require water to remove it. I can wipe down or scrub the parts with a toothbrush, set them aside, and they are ready to paint in a matter of minutes. I don't like Lacquer thinner because of the fumes, and it will eat regular plastic, but not resin.

 

Tim

I clean bare plastic with alcohol as well in some instances, but it will not do if you have used any acrylic paints or Mr. Surfacer products.   I use 1000 as a primer, and 500 as a filler, but alcohol will dissolve those.  Once you have laid down any acrylic paints, you have to stick with Dawn as a cleaner.

[BiggTim]

Definitely. I meant only on bare plastic, not over paint or primer. The 91% stuff will even damage enamels if you're not careful.

Edited January 3, 2018 by BiggTim

[Guest Peterpools]

The only time I every wash a model to remove mold release is before assembly. Before painting, I'll wiped the model down with IP, let dry and follow up with a tac cloth. After that I either wear nitrile gloves, hold the model with a paper towel or my preferred method: I wear white cotton gloves.

Peter

[TimHepplestone]

Also IPA user. Of several iterations

[Gigant]

I've been using IPA, but I was wondering about diluted Awesome Cleaner that they sell at the dollar stores?

[Gazzas]

I had a model I wanted to strip of acrylic paint.  The only thing I had with any real strength was barbecue cleaner made from SG.  I worked pretty well, requiring me to only do some gentle scrubbing with an old toothbrush.

 

I used the same stuff to clean some resin parts recently before painting.  Gladly I can say that the paint didn't act like it was being sprayed over release agent.

[CANicoll]

I also follow the Peterpools model:  When I open up the kit, I dunk everything in a sink full of Dawn (or similar) and gently scrub with an old toothbrush.  I don't dunk the resin parts, just brush them well and put them on a cloth towel to dry.  Our water here is good so hard water is not a problem.

 

Then I tend to spray all outside and inside surfaces to be painted with primer while the parts are still on the sprues.

 

As I build I work on the seams and such and re-prime as needed.  My primer also serves as the base coat for black- or white- basing.

 

Chris

[Dave Williams]

I rarely wash sprues of a new plastic kit prior to painting. The only time that I've done it is for some older Eastern European kits that had obvious mold release on all of the sprues. Modern kits from the big manufacturers, I don't see the need and haven't had any problems.

 

When I was using enamels and lacquers, I never primed. Now that I mostly use the Spanish acrylics or MMP, I always prime.

 

For resin parts/kits, I always wash with Dawn first.