Cleaning Resin car body & parts before priming

[Chevy II]

I see people are recommending to clean resin parts with Westley’s Bleach White, but the original isn’t available anymore. Has been replaced with Black Magic brand. I have read they are not the same. &nbsp
What are you guys using to clean your resin parts? Has anyone tried Simple Green?

[stitchdup]

thinners and a cotton bud then washed in clean soapy water. if i dont have thinners i use ipa. i only do a little at a time and dont soak the whole thing if its a body

[Swamp Dog]

a good scrub with Ajax or Comet cleaner followed up with a good soapy water bath then rinse well.

[diggerguy]

3 hours ago, Swamp Dog said:

a good scrub with Ajax or Comet cleaner followed up with a good soapy water bath then rinse well.

Why use such harsh cleaners? I use soap and water. Just cleaning off the release agent, By the way, what release agent do you casters use?

[bobss396]

I just use warm water and dishwashing soap, likely Palmolive. I'll let it soak a bit, then I use an old toothbrush to scrub it.

I even do this with any 3D printed part I get. I just did a body that had all sorts of crud left in the corners. 

[Bainford]

18 hours ago, Chevy II said:

Has anyone tried Simple Green?

I would be careful with Simple Green. I believe it uses similar ingredients to Castrol Super Clean. Simple Green is milder than CSC, but CSC can really mess up some resins, so I would caution against using Simple Green, too.

[stitchdup]

Ed Fluck suggests using thinners.

[espo]

Have you tried Dawn Dish Soap? This product is often used to remove crude oil residue from waterfowl without hurting the bird but dissolves the oil. Might also contact the caster of any resin bodies or parts you are using to see what they recommend as some cleaning products can and will damage curtain types of resin parts and they should know what would work the best for cleaning their castings.  

[Rick L]

Most resin castings are cast with silicone based release agents. Soapy water or isopropyl alcohol works fine for most.

[Skip]

On 5/15/2025 at 10:20 AM, Rick L said:

Most resin castings are cast with silicone based release agents. Soapy water or isopropyl alcohol works fine for most.

Second the 70 - 90% isopropyl alcohol, normally followed by a spritz of Windex.

The “Proof” of clean surface is just like on your freshly washed car, the water should sheet right off of a clean surface, where a contaminated surface will gather droplets won its  surface where it’s incompletely cleaned.

[RW033]

I soak in isopropyl alcohol, let that dry then spray with windex then wash with a toothbrush and dish soap 

[Chris V]

12 hours ago, RW033 said:

I soak in isopropyl alcohol, let that dry then spray with windex then wash with a toothbrush and dish soap 

Isopropyl alcohol can seriously damage/soften some types of cast resin. I'd strongly discourage this as a way of cleaning the parts. 

[RW033]

4 hours ago, Chris V said:

Isopropyl alcohol can seriously damage/soften some types of cast resin. I'd strongly discourage this as a way of cleaning the parts. 

I don’t use cast resin, only 3D printed resins

[Rick L]

19 hours ago, RW033 said:

I soak in isopropyl alcohol, let that dry then spray with windex then wash with a toothbrush and dish soap 

Soaking is not a good method to clean parts. Soapy water or alcohol is used as a medium to wipe or scrub the parts.

[Swamp Dog]

On 5/12/2025 at 8:47 PM, diggerguy said:

Why use such harsh cleaners? I use soap and water. Just cleaning off the release agent, By the way, what release agent do you casters use?

i been using it for many years with no problem. its like a woman if she has been good to you why change.😀

[Swamp Dog]

9 hours ago, RW033 said:

I don’t use cast resin, only 3D printed resins

you keep on soaking your 3D parts in isopropyl alcohol and leave them in their to long it will melt them. i use it also to clean 3D parts but i will not leave them in over 3 minuets at a time. i was talking to a guy one day about soaking in alcohol and he left a body in over night next morning all he had was a melted body..lol..one thing i have found out if you spray on a new paint job and you mess it up ( enamel or acrylic paint) you can soak it in  91% isopropyl alcohol starting out at 5 minuets as soon as the you finish spraying the paint. then with a old tooth brush under warn to hot water start removing what paint you can. shake the water off and keep re peteing till all the paint is removed. wash well..within 30 minuets or less you will be ready to prime again ( could take longer on some models)..

[RW033]

21 hours ago, Swamp Dog said:

you keep on soaking your 3D parts in isopropyl alcohol and leave them in their to long it will melt them. i use it also to clean 3D parts but i will not leave them in over 3 minuets at a time. i was talking to a guy one day about soaking in alcohol and he left a body in over night next morning all he had was a melted body..lol..one thing i have found out if you spray on a new paint job and you mess it up ( enamel or acrylic paint) you can soak it in  91% isopropyl alcohol starting out at 5 minuets as soon as the you finish spraying the paint. then with a old tooth brush under warn to hot water start removing what paint you can. shake the water off and keep re peteing till all the paint is removed. wash well..within 30 minuets or less you will be ready to prime again ( could take longer on some models)..

Not sure where you got that info from but in all the research and reading I’ve done on 3D printing I’ve never come across anywhere saying isopropyl will melt plastic or resin (it’s even bottled and stored in a plastic container!). I’ve lost small parts for months in the bottom of my cleaning tank and pulled them out and other than making a few trips through the spinner at the bottom there is no issue with them being melted. If something got melted then there was other issues with the print, perhaps the resin wasn’t fully cured or the walls were paper thin. I don’t claim to be an expert but I’ve done a fair amount of reading to make sure I don’t have these issues and have yet to have any, or read of any, and I wouldn’t leave parts soaking overnight but 10-20 minutes for sure I do all the time. 

[Swamp Dog]

1 hour ago, RW033 said:

Not sure where you got that info from but in all the research and reading I’ve done on 3D printing I’ve never come across anywhere saying isopropyl will melt plastic or resin (it’s even bottled and stored in a plastic container!). I’ve lost small parts for months in the bottom of my cleaning tank and pulled them out and other than making a few trips through the spinner at the bottom there is no issue with them being melted. If something got melted then there was other issues with the print, perhaps the resin wasn’t fully cured or the walls were paper thin. I don’t claim to be an expert but I’ve done a fair amount of reading to make sure I don’t have these issues and have yet to have any, or read of any, and I wouldn’t leave parts soaking overnight but 10-20 minutes for sure I do all the time. 

just telling you what i was told..why dont you leave a body in over night and see if the guy was telling a lie..🙃

 

[Chris V]

Just to clarify: There's a world of difference between polyurethane resin used for casting and the resin used for 3D-printing. It is NOT the same thing!

If you leave a cast (polyurethane) resin part in isopropyl alcohol (or brake fluid for that matter) it will soften the resin beyond use. 

3D printers use an entirely different kind of resin with different chemical/physical properties. In general 3D printed parts can be cleaned/stripped with isopropyl alcohol, but some types are more vulnerable to chemicals than others. 

[RW033]

10 hours ago, Swamp Dog said:

just telling you what i was told..why dont you leave a body in over night and see if the guy was telling a lie..🙃

 

Great advice. Maybe you should do research instead of just throwing out potentially bad advice based on “what you were told”. 

[RW033]

2 hours ago, Chris V said:

Just to clarify: There's a world of difference between polyurethane resin used for casting and the resin used for 3D-printing. It is NOT the same thing!

If you leave a cast (polyurethane) resin part in isopropyl alcohol (or brake fluid for that matter) it will soften the resin beyond use. 

3D printers use an entirely different kind of resin with different chemical/physical properties. In general 3D printed parts can be cleaned/stripped with isopropyl alcohol, but some types are more vulnerable to chemicals than others. 

Excellent point!

[R. Thorne]

This from MCW:  

[Skip]

On 6/7/2025 at 4:01 PM, Skip said:

Second the 70 - 90% isopropyl alcohol, normally followed by a spritz of Windex.

The “Proof” of clean surface is just like on your freshly washed car, the water should sheet right off of a clean surface, where a contaminated surface will gather droplets won its  surface where it’s incompletely cleaned.

Yes, agree with the soaking of Resin Cast Parts, my original comment was meant, to use the isopropyl alcohol as a surface cleaner, like the Windex. Which is what I have done for as long as I can remember, I also use this method to wash styrene/plastic kit bodies prior to painting as well.

I am getting the sheeting action with water on the surface. This was/is an old painter's test for cleaned surface, free of oil and contaminants, I've got the same sheeting action using dish washing detergent as well.

[SfanGoch]

DON"T use any products containing IPA or other industrial chemicals. Cast resin is porous and will absorb them. Spray cast resin parts with Down POWERWASH Dish Spray, scrub with a toothbrush, rinse with lukewarm water. 

[bobss396]

On 6/10/2025 at 12:00 PM, R. Thorne said:

This from MCW:  

What a radical concept... doing what the manufacturer recommends...