Help / Advice needed on removing silicone on a PU4000 tarp

**JJBrewbus** · 02-04-2019, 19:39

Hi all,

I think I might need to remove silicone from my PU4000 tarp because I never realized that one side (the PU side) doesn’t accept silicone. However, I am scared that I would really have to soak the fabric in alcohol or turpentine or something in order to remove the cured silicone, and that this process would damage the material.
Unless you have a better idea (?).

I have 3 ridgeline tie out points that drip.

Should I:
Try to remove the silicone and then add a sealant which is designed for PU?
Or
Leave the silicone where it is and try to add some other PU-friendly sealant on top?
Or
Try attaching an additional piece of PU4000 material directly over the tie out area (although the loops will still need to stick out, and this would still provide an entry point for rain)? And anyway... would I somehow glue it in place?
Or
Would seam sealing tape be of use? (I don’t have much experience with it and so I have no idea if it would stick to silicone or the PU side at all)?

Here’s the design (if this is pertinent): I made a 5 meter long tarp from PU4000, I have the darker PU side on the inner of the tarp. I used a flat-felled hybrid seam for the ridge line but I added 3 ridge line tieouts (my theory was that the tarp would live longer with the suspension not directly touching and rubbing the material). Tie outs are made from poly webbing sewn to the outside of the tarp, with Ripstop nylon reinforcements on the inside of the tarp.
All seams and stitching was given a silicone/turpentine coating.

After testing it in a rainstorm, all tie out points dripped!

I re-applied a second coat of silicone (inside and outside) with some improvement, yet the 3 ridgeline tie outs drip!

And now I have only JUST discovered that the PU side does not accept silicone (although most of the silicone is directly on the Ripstop nylon).

Has anyone else had similar problems with PU4000? What solution worked well?

Sorry for the long message — just trying to give all the information in one dollop!

JJ

**ylnfrt** · 02-04-2019, 19:57

Nice looking tarp- it looks hugh! I believe you will have better results diluting the silicone with mineral spirits, making the silicone 'fluid' enough that it flows into the stitch. As to removing the offending silicone- have you tried just rubbing it off? My experience has been that if it does not bond well, that it will rub off when dry. This all applies to silnylon/silpoly materials. Sorry- I just realized you are working with polyurethane treated material. Your's may be treated with PU on one side and silicone on the other- if so then the diluted silicone should work on the sil-treated side.

**Peabody** · 02-04-2019, 20:10

I would probably try to remove all the silicone I could, then apply some seam grip to it. Good luck!

**JJBrewbus** · 02-04-2019, 20:40

Originally Posted by ylnfrt

Nice looking tarp- it looks hugh! I believe you will have better results diluting the silicone with mineral spirits, making the silicone 'fluid' enough that it flows into the stitch. As to removing the offending silicone- have you tried just rubbing it off? My experience has been that if it does not bond well, that it will rub off when dry. This all applies to silnylon/silpoly materials. Sorry- I just realized you are working with polyurethane treated material. Your's may be treated with PU on one side and silicone on the other- if so then the diluted silicone should work on the sil-treated side.

Ylnfrt,

Thanks for the compliment.
Yes, the first coat was diluted silicone, the second coat was a little thicker. I’ll try your advice and see if it rubs off the PU side of the material, but it’ll probably stay impregnated to the nylon reinforcement patches.

**JJBrewbus** · 02-04-2019, 20:43

Originally Posted by Peabody

I would probably try to remove all the silicone I could, then apply some seam grip to it. Good luck!

Peabody,

Thank you.

As I’m in Indonesia and Seam Grip is not readily available, do you know what the main ingredients of Seam Grip are — I may be able to find a locally available product with similar contents.

**Peabody** · 02-05-2019, 07:13

I’m not sure of a seam grip alternative. I know it is urethane based and that’s why it is adherent to pu4000. Maybe thin some urethane based clear caulk and apply that? I’m really not 100% sure. I’m also not sure how to thin urethane based adhesives - I don’t think paint thinner works.