Standing in the hardware aisle staring at ten tubs of white paste is one of the most quietly frustrating parts of home repair. Spackle, joint compound, wood filler, caulk, expanding foam — every label promises to “fill any gap,” but each one behaves completely differently once it’s actually in the wall. Grab the wrong one and you’ll be back in two weeks staring at a crack that reopened, a lump that never fully dried, or a patch that bled through your fresh paint. This guide replaces the guesswork with real numbers: how long each filler actually takes to cure, how deep a gap it can fill in one coat before it sags or cracks, how much it shrinks as it dries, and how long you actually need to wait before painting over it.
We’ll walk through spackling paste, drywall joint compound (both regular and setting-type), two-part epoxy wood filler, wood putty, painter’s caulk, silicone caulk, expanding foam, and patching plaster — the fillers you’re most likely to reach for on an indoor repair. By the end, you’ll be able to match the filler to the gap in front of you instead of picking whatever tub is closest.
Quick Answer: Which Filler Should You Use?
For gaps under 1/4 inch — nail holes, hairline cracks — lightweight or vinyl spackling paste dries in 15 to 60 minutes and is paintable within 1 to 4 hours. For gaps between 1/4 and 3/4 inch, setting-type (“hot mud”) joint compound shrinks less than 3% and can be built up in one thick pass, unlike standard joint compound, which shrinks 10 to 15% and needs several thin coats. For deep wood gouges over 1/2 inch, two-part epoxy filler is the only common option with essentially zero shrinkage. As This Old House notes, setting-type compounds cure through a chemical reaction rather than by evaporation, which is exactly why they resist the shrink-and-crack cycle that plagues standard mud in deeper repairs.
| Filler Type | Cure / Dry Time | Paintable After | Max Gap Per Coat | Shrinkage |
|---|---|---|---|---|
| Lightweight spackling paste | 15–30 min | 1–2 hrs | Per product label (typically multiple coats if deeper than 1/8 in) | <5% |
| Vinyl spackling paste | 30–60 min | 2–4 hrs | Per product label (typically multiple coats if deeper than 1/8 in) | 5–8% |
| Standard joint compound (air-dry mud) | 24 hrs/coat | 24–48 hrs | 1/8–1/4 in | 10–15% |
| Setting-type joint compound (“hot mud”) | 20–210 min (by formula) | ~24 hrs after set | Up to 3/4 in | <3% |
| Two-part epoxy wood filler | 1–2 hrs sandable | 24 hrs | 2+ in (built up) | ~0% |
| Solvent-based wood putty | 1–8 hrs sandable | 24 hrs | 1/4 in | 5–10% |
| Acrylic latex painter’s caulk | Skins in 20–30 min | 30 min–1 hr (check label); full cure 7–14 days | 3/8 in unsupported | 10–20% |
| 100% silicone caulk | Skins in 30 min | Not paintable | 1/2 in with backer rod | <5% |
| Low-expansion polyurethane foam | Tack-free in 8–10 min | 24 hrs min | 1–3 in (multi-pass) | Expands 2–3x (no shrink) |
| Patching plaster | 20–30 min set | 24–48 hrs | 1/2–1 in | <5% |
How to Read Cure Time, Max Gap, and Shrinkage
These three numbers matter more than any brand name because together they predict whether your patch will actually hold.
- Cure time is how long the material needs before it reaches full strength. Some fillers dry as water evaporates (drywall mud, spackle); others cure through a chemical reaction (epoxy, setting-type mud, silicone). Chemical cures tend to be faster and shrink less.
- Max gap per coat is the deepest layer you can apply without it sagging, cracking, or taking forever to dry all the way through. Go deeper than the listed max and you risk a soft, spongy center that never fully sets.
- Shrinkage is the percentage of volume lost as the filler dries or cures. High-shrinkage fillers (10 to 20%) usually need a second, thinner skim coat to hide the dip left behind. Zero- or low-shrinkage fillers, like epoxy and setting-type mud, can often go on once and sand flush.
Spackling Paste: Best for Nail Holes and Hairline Cracks
Spackling paste is the go-to for small, shallow repairs — picture-frame holes, thumbtack marks, hairline drywall cracks. There are two main types.
| Spackle Type | Dry Time | Paintable | Max Depth | Shrinkage | Best For |
|---|---|---|---|---|---|
| Lightweight (acrylic foam-based) | 15–30 min | 1–2 hrs | Per product label (typically multiple coats if deeper than 1/8 in) | <5% | Slightly larger holes, corners |
| Vinyl (heavier paste) | 30–60 min | 2–4 hrs | Per product label (typically multiple coats if deeper than 1/8 in) | 5–8% | Slightly larger holes, corners |
Lightweight spackle is easier to sand and less likely to shrink visibly, but it’s also softer and less durable in high-traffic spots like door-handle dents. Vinyl spackle holds up a little better under abrasion but takes longer to dry all the way through. Neither is meant for deep, single-pass fills — follow the depth-per-coat limit printed on the tub (many spackling labels call for two or more layers beyond about 1/8 to 1/4 inch), and for anything deeper move up to joint compound or epoxy.
Drywall Joint Compound: Regular vs. Setting-Type
For anything wider than a nail hole — drywall seams, corner dings, patched holes — joint compound (“mud”) is the standard choice. But there are two very different families, and mixing them up is the most common reason a repair cracks a month later.
Standard (air-dry) joint compound comes premixed in a bucket and dries only as its water content evaporates. That’s why it needs about 24 hours per coat and shrinks 10 to 15% along the way — you’ll almost always need two or three thin coats to fill a 1/2-inch hole without leaving a visible dip.
Setting-type joint compound (often called “hot mud”) comes as a powder you mix with water. It hardens through a chemical reaction rather than evaporation, so it sets on a fixed schedule no matter the humidity in the room. The number in the product name — 20, 45, 90, or 210 — is the working time in minutes before it goes hard in the pan. Because it sets chemically, shrinkage stays under 3%, and you can pack a single coat up to 3/4 inch deep without the middle staying soft.
| Setting-Type Formula | Working Time | Best Use |
|---|---|---|
| 20-minute | ~20 min | Fast second coats, small repairs |
| 45-minute | ~45 min | Most drywall patch work |
| 90-minute | ~90 min | Larger patches, first coats over mesh tape |
| 210-minute | ~210 min | Big jobs where you need more time to work |
Rule of thumb: use setting-type compound for the first, deep-fill coat on anything wider than a golf ball, then finish with a thin standard-mud skim coat for an easier sand. Wait the full 24 to 48 hours after the final coat before priming — painting too early traps moisture underneath and causes flaking down the line.
Two-Part Epoxy Wood Filler: Zero Shrinkage for Deep Gouges
When the gap is in wood — a rotted window sill corner, a deep gouge in a door, a missing chunk of baseboard — epoxy filler is the strongest option on the shelf. It’s sold as two components (resin and hardener) that you mix right before use in the exact ratio the manufacturer prints on the package — some are 1:1 by volume, while others call for only a small measure of cream hardener, and an off-ratio mix can stay soft and never fully cure.
- Working time after mixing: 15–30 minutes
- Sandable: 1–2 hours
- Fully cured and paintable: 24 hours (some fast-cure formulas: 12 hours)
- Max gap: effectively unlimited — many brands are rated to rebuild missing wood sections 2 inches deep or more
- Shrinkage: essentially 0%
Because epoxy doesn’t shrink or crack the way water-based fillers do, it’s the right call anytime the repair needs to hold real structural shape — rebuilding a corner, filling a stripped screw hole, or patching a gouge you plan to carve or shape once it’s semi-cured. The tradeoffs are cost and a noticeably stronger odor while mixing, so work with a window open or a fan running.
Wood Putty vs. Wood Filler: What’s the Difference
These two get confused constantly, and the mix-up is behind a lot of ruined finishes.
| Product | Base | Cure/Dry | Max Gap | Shrinkage | Stainable? |
|---|---|---|---|---|---|
| Solvent-based wood putty | Oil/solvent | Surface dry 1–2 hrs; sandable 2–8 hrs | 1/4 in | 5–10% | Sometimes — check the label |
| Water-based wood filler | Latex/acrylic | 15–30 min per thin layer | 1/4–1/2 in | 5–8% | Poorly — usually paint-grade only |
| Two-part epoxy filler | Epoxy resin | 1–2 hrs sandable | 2+ in | ~0% | No — paint only |
Solvent-based putty stays workable longer and can sometimes be tinted to match wood stain, but it has a strong fume odor, so ventilate the room and skip it in small, closed spaces. Water-based filler cleans up with soap and water but shrinks more and skins over faster, which makes it harder to work into deep gaps in one pass.
Caulk for Interior Gaps: Acrylic Latex vs. Silicone
Caulk isn’t a filler in the traditional sense, but it’s what you reach for at the trim-to-wall line, around window casings, and at baseboard gaps — anywhere two different materials meet and need a flexible seal instead of a rigid patch.
| Caulk Type | Skin Time | Paintable | Full Cure | Max Gap | Shrinkage |
|---|---|---|---|---|---|
| Acrylic latex (painter’s caulk) | 20–30 min | 30 min–1 hr, per label | 7–14 days | 3/8 in unsupported; 1 in with backer rod | 10–20% |
| 100% silicone | 30 min | Not paintable | 24–72 hrs | 1/2 in with backer rod | <5% |
Acrylic latex is the one you want anywhere paint is going over it — trim, crown molding, baseboards. Silicone is more flexible and more water-resistant but won’t accept paint, so save it for spots that don’t need to match the wall color. For gaps wider than about 1/4 inch, press a foam backer rod into the gap before caulking; running a bead straight into an open gap that deep just encourages it to sag, crack, and pull away from one side. That backer-rod step lines up with standard sealant guidance, including the movement-capability testing covered under ASTM International’s C920 sealant standard.
Expanding Foam Filler: For Large Gaps Around Pipes and Frames
For gaps around pipe penetrations, electrical boxes, or the perimeter of window and door frames, low-expansion polyurethane foam fills space no paste filler can reach.
- Tack-free: 8–10 minutes
- Trim-ready: 30–40 minutes for thin beads; several hours for thick pours
- Full cure: 24 hours for gaps under 1 inch; up to 72 hours for gaps 2–3 inches deep
- Max gap: 1 inch per pass, up to 3 inches with multiple passes
- Expansion: whatever the can states — “low-expansion” window and door formulas are minimal-expansion, and standard gaps-and-cracks foam is rated to fill gaps only up to about 1 inch
- Paintable: only after full cure, roughly 24 hours minimum
Always reach for a “low-expansion” or “window and door” formula around frames — standard high-expansion foam can push hard enough to bow a door or window jamb out of square as it cures. Wear gloves; cured or uncured, this stuff is genuinely miserable to get off skin and fabric.
Patching Plaster: For Older Lath-and-Plaster Walls
If your house predates the 1950s, there’s a good chance you’ve got plaster walls instead of drywall. Patching plaster (a gypsum/plaster-of-Paris blend) matches that older substrate better than joint compound does.
- Set time: 20–30 minutes
- Paintable: 24–48 hours after it dries all the way through
- Max gap: 1/2–1 inch per coat
- Shrinkage: under 5%
Plaster patch sets fast, similar to setting-type joint compound, and holds up well in older homes where the surrounding wall is denser than modern drywall.
Choosing by Gap Size: A Fast Decision Table
| Gap Size | Recommended Filler |
|---|---|
| Hairline crack (under 1/16 in) | Lightweight or vinyl spackle |
| Small nail hole (1/16–1/4 in) | Vinyl or lightweight spackle |
| Drywall seam or small patch (1/4–1/2 in) | Setting-type joint compound + tape |
| Doorknob-size hole (1/2–2 in) | Setting-type compound with mesh patch |
| Deep wood gouge or rot (over 1/2 in, wood) | Two-part epoxy filler |
| Trim-to-wall gap (1/8–3/8 in) | Acrylic latex painter’s caulk |
| Pipe or frame gap (1/2–3 in) | Low-expansion foam filler |
Tips to Minimize Shrinkage and Cracking
- Apply thin coats and let each one dry or set fully before adding the next — one thick coat almost always shrinks unevenly and cracks on the surface while the core stays wet underneath.
- Lightly dampen very dry, dusty drywall or plaster edges before applying compound; a bone-dry substrate pulls moisture out of the mud too fast and weakens the bond.
- Feather the edges of every patch out 2–3 inches beyond the repair so the transition sands smooth instead of leaving a visible ridge.
- For any repair deeper than the filler’s listed max gap per coat, build it up in layers rather than forcing one thick application.
- Wait for the full paintable time on the label, not just the surface-dry time — painting too early is the single biggest reason filler patches show through later as a slightly different sheen or texture.
Frequently Asked Questions
What’s the difference between wood filler and wood putty?
Wood filler (water-based or epoxy) is meant to be applied to bare, unfinished wood before staining or painting, and it hardens into a sandable solid. Wood putty stays slightly flexible even after it dries and is designed to fill nail holes and small gaps in already-finished wood, where it won’t crack loose as the wood expands and contracts. Don’t use putty as a structural filler, and don’t use hard-drying epoxy filler somewhere that needs to flex.
Can I use spackle instead of joint compound on a drywall patch?
For small holes and cracks, yes — spackle is basically a premium, fast-drying version of joint compound made for exactly that job. For anything wider than about 3/4 inch, or for taping a full drywall seam, switch to joint compound; spackle shrinks and sands differently than mud and doesn’t bond as well with joint tape.
Why did my patch shrink and crack after it looked fine when it dried?
This almost always means the coat was applied too thick for that product’s max gap per coat. The surface skins over and looks dry while the core underneath is still wet; as that core slowly loses moisture, it shrinks and pulls a crack through the middle. The fix is to apply the same repair in two or three thinner layers instead of one thick one.
How long should I really wait before painting over caulk or filler?
Go by the paintable time on the label, not the skin-over or surface-dry time — they’re often listed separately, and the gap between them matters. Acrylic latex caulk usually feels dry to the touch in 30 minutes but isn’t fully cured for 7 to 14 days; painting immediately after it skins over is fine for most latex products, but check your specific label, since some manufacturers ask for a longer wait.
Can I speed up cure time with a fan or hair dryer?
A fan or open window helps evaporation-based fillers like spackle and standard joint compound dry a bit faster by moving humid air away from the surface. It won’t do much for chemical-cure products like epoxy, setting-type compound, or silicone, since those cure on a fixed reaction time regardless of airflow. Avoid direct heat from a hair dryer — it can dry the surface too fast, sealing in moisture underneath and causing the same crack-through-the-middle problem as an overly thick coat.
Reviewed and edited by Jason Paik. Spotted an error? Tell us — we verify and correct. See how we create content.