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'''Caulking''' is the sealing of gaps, seams, and joints with a flexible filler before painting. Caulked joints keep water and air out, and they give painted trim the crisp, seamless look that separates professional work from amateur work.

== Where to Caulk Before Painting ==

* Where [[Painting Trim|trim]] meets walls — baseboards, casings, crown molding
* Miter joints and seams in trim
* Where window and door frames meet siding or drywall
* Corner gaps in woodwork
* Around tubs, sinks, and backsplashes (with kitchen-and-bath caulk)
* Exterior joints: siding butt joints, fascia seams, penetrations — see [[Exterior Painting]]

'''Do not caulk:''' the bottom edge of exterior siding boards or weep holes — those gaps drain water by design. Never caulk over large structural cracks; investigate them first.

== Types of Caulk ==

{| class="wikitable" style="width: 100%;"
|-
! Type !! Paintable !! Flexibility !! Best For
|-
| '''Acrylic latex ("painter's caulk")''' || Yes || Moderate || Interior trim gaps, drywall seams — the default for paint prep
|-
| '''Siliconized acrylic''' || Yes || Good || Interior/exterior trim, better adhesion and water resistance
|-
| '''Pure silicone''' || '''No''' || Excellent || Tubs, showers, glass, metal — paint will not stick to it
|-
| '''Polyurethane''' || Yes (after cure) || Excellent || Exterior joints, high-movement gaps, siding
|-
| '''Elastomeric/hybrid (MS polymer)''' || Yes || Excellent || Premium exterior sealing, wide joints
|-
| '''Kitchen & bath (mildew-resistant)''' || Varies || Good || Wet areas; check the label for paintability
|}

The critical rule for painters: '''never use pure silicone where you plan to paint.''' Paint beads off silicone, and silicone contamination is nearly impossible to remove.

== How to Caulk Like a Professional ==

# '''Clean the joint.''' Remove old failing caulk with a scraper or caulk-removal tool, then dust and degrease. New caulk over dirty or failing caulk fails.
# '''Cut the tip small.''' Cut the nozzle at 45° with an opening just larger than the gap — most beginners cut far too big. Puncture the inner seal.
# '''Fill deep gaps first.''' Gaps deeper than 1/2 inch get foam backer rod first, so the caulk forms the proper hourglass profile.
# '''Run the bead smoothly.''' Hold the gun at 45°, keep steady pressure, and pull the gun along the joint at an even speed. Push-or-pull is personal preference; consistency matters more.
# '''Tool immediately.''' Smooth the bead with a wet fingertip or caulk tool in one continuous pass, pressing caulk into the gap and removing excess. Keep a damp rag in the other hand.
# '''Release gun pressure''' between runs (hit the release tab) to stop oozing.
# '''Let it cure before painting.''' "Paint-ready in 30 minutes" claims are optimistic — give acrylic latex at least 2–4 hours, longer for deep beads, or the paint can crack as the caulk shrinks.

== Caulking in the Prep Sequence ==

Caulk after [[Sanding|sanding]] and [[Drywall Repair|repairs]] but before [[Paint Primer|priming]] — or after priming, which makes gaps easier to see. Both orders work; what matters is that caulk goes on before the final topcoat so it gets painted over and protected from UV. See [[Surface Preparation]] for the full sequence.

== Common Mistakes ==

* '''Using pure silicone under paint''' — paint will not adhere; use acrylic latex or a paintable hybrid
* '''Cutting the nozzle too big''' — floods the joint and makes a mess no tooling can save
* '''Skipping the tooling pass''' — untooled beads look ropey and bond only at the surface
* '''Painting too soon''' — uncured caulk shrinks and cracks the paint film above it
* '''Caulking over dust or old failing caulk''' — the new bead peels away with the old material
* '''Filling huge gaps with caulk alone''' — anything past about 1/2 inch wide or deep needs backer rod or a wood repair first
* '''Relying on cheap caulk outdoors''' — bargain acrylic shrinks and splits within a season; exterior joints deserve polyurethane or hybrid sealants

== Frequently Asked Questions ==

=== Can you paint over caulk? ===
Over acrylic latex, siliconized acrylic, polyurethane, and hybrid caulks — yes, once cured. Over pure silicone — no; paint beads and peels off it. If you must paint where silicone was used, remove it completely or cover it with a paintable sealant formulated to bond over silicone residue.

=== How long should caulk dry before painting? ===
Follow the tube, but treat 30-minute claims skeptically. A safe rule for acrylic latex painter's caulk is 2–4 hours for thin beads and 24 hours for wide or deep beads. Polyurethane sealants often need days to fully cure before painting.

=== Should I caulk before or after priming? ===
Either works. Caulking after primer has a real advantage: primer makes gaps and shadow lines obvious, and caulk adheres well to primed surfaces. Just make sure every bead ends up under the topcoat, because unpainted acrylic caulk weathers poorly.

=== What is the difference between caulk and wood filler? ===
Caulk stays flexible and belongs in joints between materials that move — walls and trim, siding seams. Wood filler and spackle dry hard and sandable, and belong in holes and gouges within a surface — nail holes, dents, chips. Using caulk in nail holes leaves dimples; using filler in moving joints guarantees cracks. See [[Drywall Repair]] for wall patching.

=== Why does my caulk keep cracking? ===
Either the joint moves more than the caulk can stretch (cheap caulk in an exterior joint), the bead was too thin, the gap needed backer rod, or paint was applied before the caulk cured. Cut out the failed bead and redo it with a higher-quality elastomeric caulk rather than layering over it.

[[Category:Surface Preparation]]
[[Category:DIY Painting]]
[[Category:Painting Techniques]]

Caulking - Revision history

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