A few easy tips on maintaining your cars canvas roof for many years to come

[Graham M]

Hey guys, Many years ago I made my living while a teen as a "professional" detailer. Many of the tricks I learned back then I'll teach you guys here so everybody that reads this can enjoy the merits having a healthy canvas roof.

Now that winter is over, and most people are getting out their Roadsters, now is a fitting time to go over a few tips

1) *NEVER* put the roof down while it is wet. Even just damp to the touch. I know its tempting after you just washed the car, but wait until its dry. Heres why: When the canvas roof is all tucked away in its bay, its dark, warm and very moist. Bacteria love that environment and they thrive in it. Unfortunately this makes the canvas literally rot and mildew.
If you get good enough at aiming the pressure washer & soap brush, you can leave the top down while washing it. Thats what I do. What (very little) water may get on the roof is only the part thats fully exposed to the sun, so its not a problem.

2) Never drive the car in winter/freezing temps & snow. If you plan on driving your Z4 (/convertible) year round in a place that has freezing temps, snow or freezing rain then buy a hard top for the car, or leave it parked.
Water expandes when it freezes, most people know that. The reason why thats murder for the canvas: is that the water soaks into the fibers, and freezes. This CONSTANT freezing and thawing of the fabric just destroys it in only a few short seasons. You can always spot the convertibles that are driven in winter since they're faded, weak, torn, very droopy (etc) and they tear very easily since their elasticity is non-existent.
Another reason, is that if where you live happens to use salt, the salt also permeates the fabric and causes further damage to it.
Used Hardtop - $2000-$2500
New canvas - $1500-$2800.
Its not hard to figure out why I advocate either parking these cars over the winter or just use a hardtop.

3) Remove stains and dirt much the same way you would any carpet/upholstery. Using a pressure washer to blast the stains further into the fabric is just a bandaid solution. If you have stains, extract them using a proper carpet extractor and solution. If you aren't knowledgeable enough to use an extractor, check out videos on youtube, or pay a detailing studio to do it for you.
If continual stains are an issue, you may want to scotchguard the fabric. Just tape off ALL the windows and surrounding body work so there is no chance of overspray.
From there its quite simple, but only do this to a perfectly clean top. Otherwise getting the stains out after its been scotch-guarded will be quite an issue.

Well, its been quite a few years since I've ever done any detailing work on any car other then my own, so I think I've covered everything, but if I think of anything else I'll post it here. Comments & questions are entirely welcome of course.

[pokeybritches]

Thank you for this info!

[aerobod]

Originally Posted by Graham M

Hey guys, Many years ago I made my living while a teen as a "professional" detailer. Many of the tricks I learned back then I'll teach you guys here so everybody that reads this can enjoy the merits having a healthy canvas roof.

Now that winter is over, and most people are getting out their Roadsters, now is a fitting time to go over a few tips

1) *NEVER* put the roof down while it is wet. Even just damp to the touch. I know its tempting after you just washed the car, but wait until its dry. Heres why: When the canvas roof is all tucked away in its bay, its dark, warm and very moist. Bacteria love that environment and they thrive in it. Unfortunately this makes the canvas literally rot and mildew.
If you get good enough at aiming the pressure washer & soap brush, you can leave the top down while washing it. Thats what I do. What (very little) water may get on the roof is only the part thats fully exposed to the sun, so its not a problem.

2) Never drive the car in winter/freezing temps & snow. If you plan on driving your Z4 (/convertible) year round in a place that has freezing temps, snow or freezing rain then buy a hard top for the car, or leave it parked.
Water expandes when it freezes, most people know that. The reason why thats murder for the canvas: is that the water soaks into the fibers, and freezes. This CONSTANT freezing and thawing of the fabric just destroys it in only a few short seasons. You can always spot the convertibles that are driven in winter since they're faded, weak, torn, very droopy (etc) and they tear very easily since their elasticity is non-existent.
Another reason, is that if where you live happens to use salt, the salt also permeates the fabric and causes further damage to it.
Used Hardtop - $2000-$2500
New canvas - $1500-$2800.
Its not hard to figure out why I advocate either parking these cars over the winter or just use a hardtop.

3) Remove stains and dirt much the same way you would any carpet/upholstery. Using a pressure washer to blast the stains further into the fabric is just a bandaid solution. If you have stains, extract them using a proper carpet extractor and solution. If you aren't knowledgeable enough to use an extractor, check out videos on youtube, or pay a detailing studio to do it for you.
If continual stains are an issue, you may want to scotchguard the fabric. Just tape off ALL the windows and surrounding body work so there is no chance of overspray.
From there its quite simple, but only do this to a perfectly clean top. Otherwise getting the stains out after its been scotch-guarded will be quite an issue.

Well, its been quite a few years since I've ever done any detailing work on any car other then my own, so I think I've covered everything, but if I think of anything else I'll post it here. Comments & questions are entirely welcome of course.

If the top is properly treated to waterproof it, driving it in winter is not a problem. Three winters in Calgary now, my top is nice and taught and looks brand new, driven almost everyday we've had snow. This past winter had some really good top-down days, wouldn't want to spoil the opportunity to use the car with the roof down my having a hard top in place! I'm not going to worry too much about the wear and tear due to using it in the winter, I'll get at least 150,000km on the top before it needs replacing.

I don't know about using Scotchgard on the top, as the proper waterproofing compounds for the top are typically PVA based, Scotchgard may interfere with the proper penetration and waterproofing that they provide. If the top is re-treated with a proper top waterproofer to always prevent water penetrating (water always beads on the top), then snow and ice won't penetrate the fibres and cause any damage. I can actually dry the fabric as easily as the paint on the car, just by wiping it with a towel, as water just wipes off. Here is my top after 3 winters of use in snow and ice:

[Lowansa]

Caution! I used a carpet cleaner on mine before treating it and ended up with scuff marks on the top from the furniture attachment. So far I haven't found a way to remove them.

[Graham M]

Originally Posted by aerobod

If the top is properly treated to waterproof it, driving it in winter is not a problem. Three winters in Calgary now, my top is nice and taught and looks brand new, driven almost everyday we've had snow. This past winter had some really good top-down days, wouldn't want to spoil the opportunity to use the car with the roof down my having a hard top in place! I'm not going to worry too much about the wear and tear due to using it in the winter, I'll get at least 150,000km on the top before it needs replacing.

Thats just it, about treating the top. Most of us didn't do that, so this was more for them. What sort of waterproofing agent did you use?

[aerobod]

Originally Posted by Graham M

Thats just it, about treating the top. Most of us didn't do that, so this was more for them. What sort of waterproofing agent did you use?

Half a bottle of the BMW agent every 6 months (it seems that they size it for the 3-series convertible, so a whole bottle is a waste), preceded by spot treatment with the BMW soft top cleaner on any areas with ingrained dirt.

[rsquared]

I'm a noob, so forgive my asking, but since we're on the subject... do you have to let the top sit in the sun once you use the BMW protectant?

[aerobod]

Originally Posted by rsquared

I'm a noob, so forgive my asking, but since we're on the subject... do you have to let the top sit in the sun once you use the BMW protectant?

That is what is advised, but anywhere warm and dry is fine, if it isn't sunny at the time.

[Huz-Z]

What about the RaggTop product? Is it better than the BMW products?

Thanks!

[CFoote]

Good question, I'd like to know this too...

[racerbruce]

Originally Posted by aerobod

Half a bottle of the BMW agent every 6 months (it seems that they size it for the 3-series convertible, so a whole bottle is a waste), preceded by spot treatment with the BMW soft top cleaner on any areas with ingrained dirt.

Just used both BMW products - the top does not bead up....it looks entirely wet and is not repelling water.

[aerobod]

Originally Posted by racerbruce

Just used both BMW products - the top does not bead up....it looks entirely wet and is not repelling water.

It does on mine, when I spray water from a hose on it (it won't do it with soapy water due to the soap reducing the surface tension of the water), not sure why there is a difference. Perhaps BMW has multiple products, or we've applied it differently? The stuff I use from BMW for waterproofing has a milky appearance and requires dilution with 2.5 litres of water for the whole bottle. Don't have a bottle at the moment to get the part number, as I just finished using one and threw it out.