Topic: Caulk vs. Sound Deadener...

[mungus]

Hi all,

Have been using black Sikaflex Automotive 227 as a seam sealer. Great product IMHO, only one problem.

Where I sprayed the OEM wavy finish sound deadener (with a traditional Schutz gun) over the top of the 227, the 2 products react and the deadener stays sticky - forever! (so it seems anyway)
I've had some of this sitting / drying in the wheel houses of a 68' GT390 for 2 years now and its still sticky... (the OEM stuff was bitumen / butyl, Wurth still sell it as do Motospray in OZ).
So I'm about to scrape off the sound deadener where its sticky, and start again! 

I guess the OEM caulk wasn't polyurethane like most modern automotive caulks seem to be. So I'm thinking the hydrocarbon solvents in OEM type butyl deadener, reacts with the Poly caulk somehow. So what are folks using as a caulk in the wheel houses etc? The old OEM stuff I dug out was creamy and crumbly, no idea what its made of...

Thanks in advance.

[J_Speegle]

Sorry for what happened but thanks for warning others. Guess you could have chosen to do like the factory did  and just apply one product rather than two. Guess you didn't expect the undercoating product you used to look like the factory when done.

Of course on seams as you describe sound deadener was not used for the purpose of sealing these sorts of joints but guess your using that description to try and describe the final look you were going for.  Looking at your March date you included as your cars real build date, as my current understanding it was built right around the period where NJ changed product and application styles from the earlier chalk and spread with a solvent rag to a spray seam sealer that at the wheel well to floor sides as well as trunk side floors to forward trunk floor in the trunk.  As illustrated using unrestored cars below.

Here are some looks at the seam you identified  from 68 NJ cars. Just random since you didn't include when the car was assembled

8T115xxx Brushed/smeared not sprayed






8T155xxx




8T18




+++++++++++++++++++++++++++++++++++++++++++++

After the change in product and application method


8T194xxx





8T197xxx  Cars assigned VINs higher than 8T200000 were the subject of an earlier discussion and thread




Going to move to the 68 section since we have the details about early and late 68 NJ cars specifically

[mungus]

Thanks Jeff, comprehensive, informative reply as usual! 
Mine looked like the 8T18 trunk photos, but there's spray on wavy type sound deadener in there too.
The wheel houses have that wavy look spray on sound deadener. Whether it was OEM or an older post mfg application? I can't say.
Just not sure what modern sealer is the best to use to avoid the reaction I got...

[J_Speegle]

Thanks Jeff, comprehensive, informative reply as usual! 
Mine looked like the 8T18 trunk photos, but there's spray on wavy type sound deadener in there too.
The wheel houses have that wavy look spray on sound deadener. Whether it was OEM or an older post mfg application? I can't say.
Just not sure what modern sealer is the best to use to avoid the reaction I got...

Hmm can't see Ford or the workers putting in addition effort and spending the time to do two coats but your reporting what you see or found. Guessing the car was unrestored when you got it

Guess the possible option would be to remove both products and if your doing two coats apply the first and then use a different spray product made with similar makeup sprayed very close and narrow pattern using a very slight wave motion at a slight angle to produce a somewhat consistent wave like originals. Of course practice on some boxes - the corners and edges where the sides, corners and base come together  to get the technique worked out and you can also test the compatibility at the same time.  No one said it would be easy or cheap    Think we try and remind people of that all the time on the site.