Yup, I know nothing about matching smooth molded plastic to the textured trim on a MINI, so I went digging. This all started with me purchasing the Gigamot front lip spoiler for my F56 JCW:

F56 Front Lip Spoiler

This is provided as an unfinished piece, needing some craftsmanship to get it to look like the picture above.


What I had to work with

With some help from ECS and online searches here on NAM and on YouTube I found a lot of info for the rattle can DIY’er. The problem was that this info is scattered all over the info space world and I thought it might be helpful to put all of my collective wisdom on this subject into one place. Maybe someone else will find this to be helpful.

This all started with me making a post on someone else’s thread who was doing some body work on his MINI to see if they had done texture coating on plastic trim. ECS responded with a link to a couple of SEM products they carry for doing this sort of thing:




In watching videos on the “how to” I found that the following was recommended:


As I said, I watched a few YouTube videos on how to do texture coating:

This first video is the SEM product use video.

Then I have a couple of shop videos that were helpful


Once done with all of that, I was all ready to go…

Well, more to come as I dig into this project.

 

Interesting.
I used the SEM 839853 after repairing a deep gouge on my factory (Polypropylene) wheel arch and front lip.
It worked fairly well if sprayed correctly from a distance. For areas that sprayed out too smooth, I allowed the product to flash off a bit and them used a chip brush (cut the bristles short and stiff used a wire brush to randomize the bristes) and gently dabbed the areas in a random pattern blending the texture.
After 24 hours, I went over the entire wheel arch and front lip with black trim dye.
Looking forward to your thoughts and experience.

 

It all starts with the prep. 400 grit wet and dry sandpaper; dry. There was still some seam flashing from the molding process that needed to be removed. This all came down nicely with that paper. I followed that up with a gray (fine?) Scotchbright pad. Because it is going to be texture coated, I felt that perfection was a less of a concern than if it was going to gloss coated.


Surface prep sanding

I followed this with a wipe down with acetone. Not sure this is a good idea for all plastics, as it might dissolve or soften some, but it worked will on this one. A side note, this was not a thermal resin plastic as it didn’t soften with heat.

Next is the adhesion promoter. The SEM products were all easy to use. For the adhesion promoter and the texture spray, I followed the directions on the side of the can. Note, that the adhesion promoter appears to not have a rattle in the can. Just shake it until your arm falls off. As for the trim black paint, don’t count on the can for any help. That is all in the technical data sheet on the SEM web page.

This is my target texture, the OEM MINI trim:

This was my target for the texture

My “paint booth”


The splitter holder

The adhesion no-rattle can says one light coat, wait 5 minutes, then one wet coat. I can do that. Then top coat after 15 min but no more than 30 min.

For the texture coating, again, the can… 1 to 4 dusting coats, 18” to 24” away, with a flash between coats of 3 to 5 minutes.

I practiced this on a smooth plastic coated wall board. Glad I did, because I needed to develop a technique and to see how may coats it would take to get full coverage. I was happiest after 4 coats at about 24” away.

And, Oh, the can says that there will be a glob of clear stuff to come out first. Yes, that is true. You need to do a spray on something like a doggy pee pad before starting any of this.

After one texture coat:

One texture coat


4 texture coats:

4 texture coats


Texture-ized

Painting is to come.

 

You post while I was writing my 2nd post…

The distance is really important. The MINI texture is really small and I found it hard to match the size. Mine wound up larger, even at 24”.

I also found that how the “dusting” was done also affected the results. That is, how fast I moved the spray across the surface of the piece being sprayed. In my practice piece, I had issues with starts and stops put too much over an area already covered. I found that too wet made little blobs.

I like your brush idea for repairs like that and blending.

 

Good write up so far!
I agree maintaining a proper distance and "dusting" (not too wet/not too dry). I did do a little 400grit sanding after my 2nd coat. The product that I'd used to fill the gouges tended to look a bit glossy even though I pre-textured it with the stipple brush before applying the SEM.
I was surprised how well the SEM sanded just like some of the catalyzed or lacquer automotive primer that I'm use to.
I assume this front spoiler will be going on the 2019 JWS...
Can't wait to see the finished results!