PFAS free soft top waterproofing
 

I wanted to redo the waterproofing on my Boxster soft top, but discovered that nearly all of the products to do this are based on PFAS per- and polyfluoroalkyl substances, e.g. 303 Fabric Guard and 3M ScotchGuard. I don't really want to create a debate over that, but there is emerging evidence that they cause a ton of health and environmental problems, and many countries and stores have begun to ban these products (see: proposed european ban, USA, Lowes). They are endocrine disruptors, and persist in the environment almost indefinitely.

So I wanted to find an alternative that will be safe and effective for the car, and safe for my family. One thing I found was this list of PFAS free consumer products: https://pfascentral.org/pfas-free-products/

The first thing was to identify the actual materials used in the top, to find what would be chemically compatible. Supposedly the 986 Boxster factory top is Sonnenland A5.0 fabric from Haartz. This material has 3 layers: acrylic (outside), butyl rubber (middle membrane), and polyester/dacron (interior layer). So the goal is to find something compatible with acrylic fabric. The outer layer being acrylic means it's basically the same thing as Sunbrella, as used on sailboat sun covers, and sun umbrellas.

The best candidate I found seems to be Nikwax Solarproof, a PFAS free waterproofer for synthetic fabrics that also protects from UV, so could possibly be even better at protecting the soft top vs the commonly used PFAS based waterproofers that lack UV protection. It seems to be widely regarded by outdoor gear people, especially for waterproofing things like tents, tarps, and raincoats. They also claim it doesn't really need re-application, and a single application will double the life of outdoor fabrics. I don't have any affiliation with this company or experience with their products.

Has anyone else considered this issue and have any suggestions or ideas?

Also, I wonder if waterproofing is really even necessary after learning about how the soft top is made? The butyl rubber middle layer should be extremely waterproof, and even seal around threads sewn through it.

In the year and a half I've had my car, I've driven through some serious rain storms and the top didn't leak a drop, without applying anything to it- and it doesn't bead, so it seems like it has nothing applied at this point.

I "water" proof mine about once every year to year and a half, but not to renew water repellency but rather to enhance UV protection. I think it helps keep it looking darker longer. I too have never had an issue with the top leaking.

Periodic retreatment is appropriate, especially for cars that live outside.

:rolleyes:

Ive used Chemicsl Guys top preserver..after cleaning.the top has a nice sheen and repells rain better.

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Thank you for the information. Those chemicals have polluted a local river - the Cape Fear River and possibly some town water supplies in Eastern NC. Sadly, appears that one company exported pfas waste from Europe, sending it to Eastern NC because it wasn’t on our states radar as dangerous. Legal yes, Ethical no.

Thanks! According to the website/MSDS this one is made from polyacrylic acid, quaternium-15, and water so totally PFAS free. This might be an even better choice than the nikwax one, being made specifically for convertibles, and also having UV protection.

I already applied the nikwax to my Boxster roof so I'll have to report back next time the top gets wet... but if I hadn't, I think I'd try this instead.

I've always used brush on Renovo Ultraproofer, I'm not sure what is in it, but it's not a spray or aerosol you brush it on. I still have the original bottle I bought several years ago, it used to be hard to get, but it looks like you can get it on Amazon now. :cheers:

The MSDS sheet for this says it's a "Modified Fluorocarbon Aqueous emulsion." So I think most likely this is a PFAS based product (which is a type of fluorocarbon), but it's hard to tell for certain without asking them, as they don't disclose this online anywhere I could find.

I did one application of the Nikwax Solarproof shortly after starting this thread, and want to follow up to say that it works absolutely excellent. I applied it with a spray bottle, and a small paintbrush, which I used to spread it around and apply extra coverage to seams.

I've done a bunch of long drives in heavy rain recently, and it still beads off (see photo). I really recommend this as a better alternative to the commonly used products because it doesn't have PFAS and it provides UV protection. I've also used it to waterproof a 20 year old tent that had lost it's waterproofing, which stayed totally dry through a rainstorm while camping.

http://986forum.com/forums/uploads02...1670260327.jpg

Thanks for the update. I just used 303 on mine and will check out Nikwax next time I waterproof.

That pic looks very impressive!... Since 2008, none of my 4 Boxster's or current 996 cab have ever leaked a drop despite my lack of treatment. My statement is just that...not an opinion on weather to treat or not.
I love the way the top is beading water on your car...it makes your car looked well cared for and certainly doesn't seems like it would be an effective treatment worth consideration.

Thanks for sharing your results!

Without running out into the cold garage to check for sure, I'm pretty sure what I've been using on my top is the 303 Fabric Guard. (It's been at least a couple years since I've done a treatment :o That's probably at least in part because this car is not very often in the rain.)

I've liked the results I've gotten with the 303, but, having said that, I am not opposed to switching for environmental reasons. One of the aspects that I've liked about what I've used up to now is not just the waterproofing but also the darkening effect it has. Kind of brings out the black of the top again. It's hard to tell from your pic—it may just be a lighting issue—but I'm not seeing that result. The restored 'blackness' that is.

In your photo...is it just a lighting issue?

In my research above to see what the fabric is made from, it's pretty clear that the fabric is totally waterproof because of the middle membrane, even if the outside canvas gets soaked. I think you're right, in most cases the top is still waterproof even if not treated. Still I imagine it would dry faster, look better, and be less likely to get mildew or water spots if treated.

I think my top is pretty dark black still, despite how grey it looks in the photo. I think that it's mostly reflecting the grey sky (my car is black also, but looks grey in the photo). However, I didn't notice the waterproofing changing the coloration at all. I think a faded top would still look faded with the product I used here.

3M is going to stop making PFAS containing waterproofing products: https://www.reuters.com/business/3m-stop-making-forever-chemicals-take-up-23-bln-charge-2022-12-20/

I imagine other companies will follow suit, and these will be banned soon. I imagine the same companies everyone is using will soon reformulate the products to be PFAS free.

I live in Central California, my car is 20yrs old and the black top still looks like new. I only use water on it.