Need Home-Made Caulk Spreading/Smoothing Idea

[ugoleaf]

Hello. I cleaned the sides of my bathroom sink off old moldy sealant. Used utility knife flrst. Then scrubbed the remainder with scotch with acetone, then white vinegar and then took paper towels soaked in diluted bleach and placed them around next to recesses for 2 hours. Do I need to wipe off the remainder of chemicals that could have dried up before applying new sealant?

As for applying new sealant I need a smoothing tool. I was told I should not do it with finger. Here's a picture of a smoothing tool I was suggested. But I don't want to spend money on somethingI will use once. I was thinking if I can find something at home to do the job, like cutting shape of unused card that woukd match sink's recesses. But it won't have the pressure for smoothing the sealant like commercial sealant spreader has I think:

Screenshot_20230814_071203_Samsung Internet.jpg (48.8 KiB) Viewed 560 times

I wonder how thick the layer of new sealant must be in recesses. Here's a picture to go with my questions about sealant layers:

sink-silicone-sealing.jpg (13.34 KiB) Viewed 560 times

The old sealant was somewhere in the middle (yellow). Should I apply the same level or can apply the smallest and do the smoothing with my finger? I can put 2 gloves on just in case if it's for safety concerns. The issue with small layer of sealant would be the it won't cover most of the protruding countertop's edges. That means that splashes of water would reach the surface and mold will eventually form? I have about half of sealant's tube left so I don't know if I should go crazy and apply the thickest layer (red). Maybe I can apply something in the middle (yellow) and after sealant is dried up add a thin layer to cover edges' surface?

[Grendel]

I normally clean off with meths to be honest , cleans and dries quickly. As for tools any stiffish plastic card will do , an old credit card for instance. You will be able o get enough pressure because frankly you don't need much. You could always screw the card to a bit of dowel if you feel it needs a handle. As to how much to put on I'd say the biggest mistake most people do is use too much . It then builds up on the tool or finger and spreads and gets everywhere and makes a mess. It's easier to make a neat job with a small bead. I can't say I fully understand your diagram but either way I'd say the smallest bead that will do the job.

[ugoleaf]

As for tools any stiffish plastic card will do , an old credit card for instance. You will be able o get enough pressure because frankly you don't need much.

I have a thick carton that I could cut out in shape of triangle. I have remains of transparent blister pack. It's actually almost triangle shaped and has an angle too. I could find plastic card I think too.

Here's how these protruding edges of countertop look around inside the sink (it's the before photo so disregard the old silicone). They protrude around 4-7mm towards the center of the sink because sink it not been installed accurately in the center. If I put little of sealant the surface that's below them will not be covered fully. Maybe I should apply second layer of sealant after letting first layer dry?

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[Someone-Else]

Credit cards are a tad on the thin side, I got myself a set of Click me very good don't bend / snap like credit cards do

[Grendel]

As for tools any stiffish plastic card will do , an old credit card for instance. You will be able o get enough pressure because frankly you don't need much.

I have a thick carton that I could cut out in shape of triangle. I have remains of transparent blister pack. It's actually almost triangle shaped and has an angle too. I could find plastic card I think too.

Here's how these protruding edges of countertop look around inside the sink (it's the before photo so disregard the old silicone). They protrude around 4-7mm towards the center of the sink because sink it not been installed accurately in the center. If I put little of sealant the surface that's below them will not be covered fully. Maybe I should apply second layer of sealant after letting first layer dry?

The fact that the sink and top are slightly out of line doesn't really matter as the mastic doesn't need to come to the edge of the countertop , you only need enough to cover the join between sink and top. Use as little as possible and you'll only need to apply more if it hasn't covered but I can't really see that being necassary.

[ugoleaf]

The fact that the sink and top are slightly out of line doesn't really matter as the mastic doesn't need to come to the edge of the countertop , you only need enough to cover the join between sink and top. Use as little as possible and you'll only need to apply more if it hasn't covered but I can't really see that being necassary.

Well what I meant about countertop edge is the surface below it won't be fully covered and mold will eventually appear on it. Here's a photo with what I refer to:

Screenshot_20230814_171246_Gallery.jpg (53.34 KiB) Viewed 518 times

By the way it appears the sink is fixated with some kind of glue, maybe epoxy to the countertop. There are no other solid fixtures that hold it in place. I was told to remove sealant from crevices but I don't want to weaken the binding between sink and countertop... I don't know. I will just spray mold remover foam and leave it for 12 hours.

[Grendel]

The purpose of the mastic is to seal any gap between sink and countertop. It doesn't need to be smeared all over the underside of the overhang. If anything it would probably make things worse as it will make cleaning more difficult . Mastic has anti mould properties ,( or so they all claim) but will eventually have mould form on it. If it's daubed all over the u derside of the countertop you'll just be making more work for yourself in the near future. Saying all that if the sink is bonded to the top I'd question if mastic is required at all. If water isn't getting past that seal then the seal is doing the job.

[wine~o]

ugoleaf, as you don't live in the UK I cannot recommend a "product" to get rid of the mould that I would have access to. Bleach mixed 50/50 with water should make short work of it, gloves needed obv. and a spray bottle OR an old soft toothbrush. leave for 20/30 minutes then rinse.

[fin]

sealing stuff up is not that difficult. often people make it more difficult than it need be.

cut the nozzle to the size you need. cut it square not at 45 degrees like some people do.

hold the gun at 45 degrees to the join you are wanting to seal up

clean soapy water in a spray bottle.

spray the new sealant and also spray your fingers and tool off.

you can also go with tools such as a fugi kit. or other tools which are available cheaply enough.

dont spit on it

[ugoleaf]

cut the nozzle to the size you need. cut it square not at 45 degrees like some people do.

hold the gun at 45 degrees to the join you are wanting to seal up

I will be able hold the gun at 60 degrees due to no space for adjustment. Maybe I should have spent more time scrubbing out more of the old sealant from crevices. Because in some places there is a clearance of 2 mm inside the crevices for new sealant and in some places there is none... In the worst case what can happen to new sealant?

[fin]

you really need to clear all the old stuff and all the mould etc. clean it all back so that its all looking brand new. can you not get sealant remover?

[Grendel]

I find nylon or stainless steel scourer pads and meths with a little elbow grease a decent way to remove the gunge but either way it really needs to come off..
It can be difficult to apply mastic in situations like this where it's almos impossible to physically fit the gun in. It's possible to use a short section of rubber or plastic tube on the end of the nozzle to allow the gun to be outside the bowl. It's also possible to bend an old knife or spoon to form a tool that you apply the mastic to and then onto the sink in a similar fashion to using a pointing trowel. Awkward but something I have had to do in the past...

[ugoleaf]

you really need to clear all the old stuff and all the mould etc. clean it all back so that its all looking brand new. can you not get sealant remover?

Sealant remover does not get into deep crevices and weakens silicone that it comes off. It's all elbow grease there and there is little I could do to remove deeply nested sealant either with utility knife or throwel. I completed the task but I would give it 3 out of 10. First mistake I did not listen to cut tube's nozzle square because I thought I will manage applying it on angle which did not go so well. Another mistake is having to remove sealant that would accumulate in front of nozzle which I had to remove frequently. That gave some time to sealant to slightly harden. Third mistake is using cardboard cutout which I attempted to shape according to corners of the sink instead of using plastic card. The cardboard cutout had glossy surface to which I applied soap but it resulted in sealant tugging a bit as it was already just slightly hardened. The task took longer to complete as I had to remove sealant's remains with vinegar and found some rubbing alcohol. Preparation took time too because I carefully applied masking tape.

[Grendel]

Not quite sure how you managed or had the patience to use masking tape on a round concave surface. I wouldn't have bothered in all honesty. If the sealant is accumulating to such a degree on the nozzle or in front of the nozzle suggests to me that the nozzle has been cut too short allowing more mastic out than is necessary or you are simply moving too slowly or a combination of the two. Cardboard can be ok as a use and chuck type of tool but can be absorbant . It's all good practice though at the end of the day...
Time spent in preparation and cleaning isn't wasted as it shows in the final finish.

[ugoleaf]

Not quite sure how you managed or had the patience to use masking tape on a round concave surface. I wouldn't have bothered in all honesty.

I would use general tape because it seems to stick better but masking tape allows for that flexibility needed when you need to readjust it frequently on inconsistent surface.