---
title: "Which one? Glue, drill bits, grit, blades and paint"
description: "Which glue for plastic, which drill bit for tile, which grit for stripping paint, which paint for galvanised metal — with the reason behind each answer."
url: https://atoneplace.net/which/
site: "At One Place"
---

# Which one?

99 answers on picking the right glue, bit, grit, blade, paint, screw or lubricant for a material. Each page gives the physical reason behind the recommendation, because that transfers to materials not listed here and a brand name does not.

## Three that save the most trouble

- Polypropylene and polyethylene resist almost every adhesive, because their surface energy is too low for glue to wet them. This is not a product problem — it is physics, and it needs a specific primer rather than a stronger glue.
- WD-40 is a water displacer and penetrant, not a lubricant. It evaporates and can wash away the grease that was doing the work, which is why it eventually makes locks worse rather than better.
- Never use a hammer drill on tile. Percussion shatters it. Rotary mode with a spear-point or diamond bit, and keep it cool.

## Glue and adhesive

- [Which glue works on plastic?](https://atoneplace.net/which/glue-plastic/) — It depends entirely on which plastic — identify it first, because solvent cement is unbeatable on some and useless on others.
- [Which glue works on polypropylene and polyethylene?](https://atoneplace.net/which/glue-polypropylene/) — Ordinary adhesives cannot wet these plastics at all. Use a polyolefin primer with cyanoacrylate, an MMA structural adhesive, or weld the plastic.
- [Which glue works on wood?](https://atoneplace.net/which/glue-wood/) — PVA wood glue for anything indoors; a water-resistant grade (Type I / D4) or polyurethane for anything that gets wet.
- [Which glue works on metal?](https://atoneplace.net/which/glue-metal/) — Two-part epoxy for anything structural, cyanoacrylate for small dry parts, and MMA where the surface cannot be properly prepared.
- [Which glue works on ceramic?](https://atoneplace.net/which/glue-ceramic/) — Two-part epoxy for anything that will be handled or loaded, cyanoacrylate for a clean break on a display piece — and neither is dishwasher-proof.
- [Which glue works on shoes?](https://atoneplace.net/which/glue-shoes/) — A flexible shoe repair adhesive — polyurethane or a neoprene contact cement — never superglue, which cracks within a day of walking.
- [Which glue works on fabric?](https://atoneplace.net/which/glue-fabric/) — A washable fabric adhesive or a fusible bonding web — and never superglue, which reacts with cotton violently enough to burn.
- [Which glue works on glass?](https://atoneplace.net/which/glue-glass/) — UV-cure glass adhesive for an invisible joint, clear epoxy where it must hold load, and neutral-cure silicone where it must stay flexible or wet.
- [Which glue works on PVC pipe?](https://atoneplace.net/which/glue-pvc-pipe/) — PVC solvent cement with its matching primer — and PVC, CPVC and ABS cements are not interchangeable.
- [Which adhesive should I use for tiles?](https://atoneplace.net/which/glue-tile/) — A cement-based thin-set in almost every case; ready-mixed tub adhesive only on small dry walls, never on floors or in showers.
- [Which glue works on a phone screen?](https://atoneplace.net/which/glue-phone-screen/) — A pre-cut adhesive gasket, or a flexible B-7000-type adhesive around the frame — superglue destroys screens and is the classic mistake.
- [Which glue works on rubber?](https://atoneplace.net/which/glue-rubber/) — Contact cement for large flexible areas and rubber-toughened cyanoacrylate for small ones — but silicone and EPDM need a primer or they will not bond at all.
- [Which glue is waterproof for outdoor use?](https://atoneplace.net/which/glue-outdoor/) — Polyurethane or epoxy for rigid joints, MS polymer where the joint has to move — and check the water-resistance class rather than the word "waterproof".
- [Which glue works on acrylic?](https://atoneplace.net/which/glue-acrylic/) — A solvent cement run into the joint by capillary action — not a tube adhesive, which will always look like a repair.
- [All 20](https://atoneplace.net/which/glue/)

## Drill bit

- [Which drill bit should I use for tile?](https://atoneplace.net/which/drill-bit-tile/) — A spear-point carbide or diamond bit in rotary mode only — hammer action shatters tile, every time.
- [Which drill bit should I use for metal?](https://atoneplace.net/which/drill-bit-metal/) — An HSS twist drill, ideally with a 135° split point, run slowly with firm pressure and cutting fluid.
- [Which drill bit should I use for concrete?](https://atoneplace.net/which/drill-bit-concrete/) — An SDS-plus carbide bit in a rotary hammer — a normal hammer drill will get there eventually and blunt several bits doing it.
- [Which drill bit should I use for masonry?](https://atoneplace.net/which/drill-bit-masonry/) — A carbide-tipped masonry bit in hammer mode for brick and block; step up to an SDS rotary hammer above about 10 mm.
- [Which drill bit should I use for porcelain tile?](https://atoneplace.net/which/drill-bit-porcelain-tile/) — A diamond core bit, cooled with water, at low speed — carbide spear points do not cut porcelain.
- [Which drill bit should I use for stainless steel?](https://atoneplace.net/which/drill-bit-stainless-steel/) — A cobalt bit at low speed with heavy constant pressure and cutting fluid — and never let it stop cutting.
- [Which drill bit should I use for wood?](https://atoneplace.net/which/drill-bit-wood/) — A brad point bit for clean holes up to about 13 mm; an auger for depth and a Forstner for a flat bottom.
- [Which drill bit should I use for plasterboard?](https://atoneplace.net/which/drill-bit-plasterboard/) — Almost none — an ordinary HSS or brad point bit in rotary mode, and the real question is which fixing goes in the hole.
- [Which drill bit should I use for glass?](https://atoneplace.net/which/drill-bit-glass/) — A spear-point carbide or a diamond bit, run slowly under water — and toughened glass cannot be drilled at all.
- [Which drill bit should I use for plastic?](https://atoneplace.net/which/drill-bit-plastic/) — An HSS bit ground to a shallower rake, or a plastic-specific bit, at low speed with a backing board — acrylic especially will crack.
- [Which drill bit will go through hardened steel?](https://atoneplace.net/which/drill-bit-hardened-steel/) — Solid carbide in a rigid setup, or soften the spot first — HSS and cobalt cannot cut anything much above 50 HRC.
- [Which drill bit should I use for aluminium?](https://atoneplace.net/which/drill-bit-aluminium/) — A sharp HSS bit at high speed with a wax or paraffin lubricant — the problem is aluminium sticking to the bit, not hardness.
- [Which bit should I use for large holes in wood?](https://atoneplace.net/which/drill-bit-large-holes-wood/) — Spade for speed and roughness, auger for depth, Forstner for a clean flat bottom, hole saw for big diameters in thin stock.

## Sandpaper grit

- [Which sandpaper grit for bare wood before finishing?](https://atoneplace.net/which/sandpaper-bare-wood/) — 80 to 120 to 150 on softwood, finishing at 180 or 220 on hardwood — and stop there, because over-sanding ruins stain.
- [Which sandpaper grit removes paint?](https://atoneplace.net/which/sandpaper-stripping-paint/) — 40 to 80 grit open-coat aluminium oxide or ceramic — but test for lead paint before sanding anything painted before the 1990s.
- [Which sandpaper grit removes rust?](https://atoneplace.net/which/sandpaper-metal-rust/) — 60 to 80 grit to strip scale, 120 to 180 to blend — then prime the same day, because bare steel flash rusts within hours.
- [Which sandpaper grit between coats of paint or varnish?](https://atoneplace.net/which/sandpaper-between-coats/) — 220 to 320 grit with almost no pressure — you are knocking off dust nibs, not removing the coat.
- [Which sandpaper grit for plasterboard and filler?](https://atoneplace.net/which/sandpaper-drywall/) — 120 to 150 grit to level joint compound and 220 for the final pass, ideally on a mesh with a vacuum attached.
- [Which sandpaper grit for plastic?](https://atoneplace.net/which/sandpaper-plastic/) — Start at 320-600 wet for scratches, work up to 2000, then finish with a plastic polish — and keep it cool.
- [Which sandpaper grit for car body filler?](https://atoneplace.net/which/sandpaper-body-filler/) — 80 grit to shape, 180 to refine, 320 before primer and 400-600 on the primer before paint.
- [Which sandpaper grit for a final finish?](https://atoneplace.net/which/sandpaper-final-finish/) — 400 to 600 dry, or 800 to 2000 wet on a fully cured film, followed by a polishing compound.
- [Which sandpaper should I use for wet sanding?](https://atoneplace.net/which/sandpaper-wet-sanding/) — Silicon carbide wet-or-dry paper, water with a drop of detergent, a rigid block, and 800 grit upwards.

## Blade

- [Which blade cuts metal?](https://atoneplace.net/which/blade-metal/) — A bi-metal or carbide-tooth blade with at least three teeth in the cut — that tooth-count rule matters more than the machine.
- [Which blade cuts tile?](https://atoneplace.net/which/blade-tile/) — A continuous-rim diamond blade with water — and cut wet, because dry cutting tile produces respirable silica dust.
- [Which circular saw blade for wood?](https://atoneplace.net/which/blade-wood/) — 24 teeth for ripping and framing, 40 for general work, 60-80 for a clean crosscut finish.
- [Which blade cuts plywood without tearout?](https://atoneplace.net/which/blade-plywood/) — A sharp 60-80 tooth blade, a scoring pass, tape on the line, and the good face oriented for the tool you are using.
- [Which blade cuts brick?](https://atoneplace.net/which/blade-brick/) — A segmented-rim diamond blade, cut wet or with on-tool extraction — brick and mortar dust is a serious silica hazard.
- [Which blade cuts laminate?](https://atoneplace.net/which/blade-laminate/) — A triple-chip or negative-hook blade for worktops, and a reverse-tooth jigsaw blade for laminate flooring cut face up.
- [Which blade cuts acrylic?](https://atoneplace.net/which/blade-acrylic/) — A triple-chip negative-hook blade on a table saw, or score-and-snap for thin sheet — and keep the feed steady so it does not melt.
- [Which blade cuts glass?](https://atoneplace.net/which/blade-glass/) — None — a tungsten carbide scoring wheel, one firm pass with oil, then snap it. And toughened glass cannot be cut at all.
- [Which blade cuts plasterboard?](https://atoneplace.net/which/blade-plasterboard/) — A utility knife for straight cuts and a jab saw or multi-tool for cutouts — a circular saw is the wrong tool entirely.
- [Which blade cuts plastic pipe?](https://atoneplace.net/which/blade-plastic-pipe/) — A fine 24 TPI hacksaw or a proper pipe cutter — and deburr the inside afterwards, which is the step people skip.

## Paint

- [Which paint goes over previously painted wood?](https://atoneplace.net/which/paint-painted-wood/) — Clean it, key it and spot-prime bare areas — and find out first whether the existing paint is oil or water based.
- [Which paint should I use on bare wood?](https://atoneplace.net/which/paint-bare-wood/) — Knotting solution on the knots, a wood primer, then your topcoat — and prime end grain twice.
- [Which paint sticks to plastic?](https://atoneplace.net/which/paint-plastic/) — Any paint, provided an adhesion promoter goes on first — and on polypropylene or polyethylene, the promoter is not optional.
- [Which paint should I use in a kitchen?](https://atoneplace.net/which/paint-kitchen/) — A scrubbable acrylic eggshell or satin on the walls — and for cabinets, degrease, prime and use a proper cabinet enamel.
- [Which paint should I use in a bathroom?](https://atoneplace.net/which/paint-bathroom/) — A moisture-resistant acrylic in a satin or eggshell sheen with a mould inhibitor — but ventilation, not paint, is the actual fix.
- [Which paint should I use on metal?](https://atoneplace.net/which/paint-metal/) — Remove the rust, apply a rust-inhibiting primer the same day, then an alkyd or a direct-to-metal acrylic.
- [Which paint should I use on a ceiling?](https://atoneplace.net/which/paint-ceiling/) — A flat matt emulsion — and if there is a water stain or nicotine, seal it with a shellac-based stain block first.
- [Which paint can I use on tiles?](https://atoneplace.net/which/paint-tiles/) — Tile paint over an epoxy or adhesion primer on a thoroughly degreased and abraded glaze — and expect a limited life in a shower.
- [Which paint should I use on a fence?](https://atoneplace.net/which/paint-fence/) — A penetrating stain or fence treatment rather than a film-forming paint — and let new pressure-treated timber weather first.
- [Which paint should I use on a floor?](https://atoneplace.net/which/paint-floor/) — Two-pack epoxy on concrete after a moisture test and a proper grind; floor-grade varnish or floor paint on timber.
- [Which paint should I use on radiators?](https://atoneplace.net/which/paint-radiators/) — A radiator enamel — water-based acrylic ones no longer yellow, which ordinary gloss on a hot surface always will.
- [Which paint should I use on exterior masonry?](https://atoneplace.net/which/paint-exterior-masonry/) — A breathable mineral or masonry paint — and on an old solid wall, breathability matters more than any durability claim.
- [Which paint sticks to galvanised metal?](https://atoneplace.net/which/paint-galvanised-metal/) — A mordant wash, a self-etch primer or a purpose-made acrylic primer for galvanising — ordinary oil-based primer peels off in sheets.
- [Which paint can I use on uPVC?](https://atoneplace.net/which/paint-upvc/) — A uPVC-specific paint or an adhesion promoter with an acrylic topcoat — and avoid dark colours, which can distort the frame.

## Screw

- [Which screw and pilot hole should I use for wood?](https://atoneplace.net/which/screw-wood/) — A pilot hole matching the screw's core diameter in the lower piece and a clearance hole in the upper one — that is what makes a joint tight.
- [Which screw should I use for decking?](https://atoneplace.net/which/screw-decking/) — Stainless steel — 304 inland, 316 near the coast — or a screw specifically rated for modern treated timber, which eats ordinary zinc plating.
- [Which screw should I use in masonry?](https://atoneplace.net/which/screw-masonry/) — A concrete screw into a precisely sized hole, or a plug and screw — and hollow block needs a different anchor entirely.
- [Which screw should I use for plasterboard?](https://atoneplace.net/which/screw-plasterboard/) — Coarse-thread bugle-head drywall screws into timber studs, fine-thread into metal studs — and never use them for anything structural.
- [Which screw should I use in MDF?](https://atoneplace.net/which/screw-mdf/) — A straight-shank MDF screw with a parallel thread, always into a pilot hole — the edge splits without one.
- [Which screw should I use for sheet metal?](https://atoneplace.net/which/screw-sheet-metal/) — A self-drilling (Tek) screw with a drill point matched to the material thickness, or a self-tapping screw into a correctly sized pilot hole.
- [Which screw should I use in chipboard?](https://atoneplace.net/which/screw-chipboard/) — A twin-thread chipboard screw with an unthreaded shank under the head, so it pulls the joint together instead of bursting the board.
- [Which screw should I use in plastic?](https://atoneplace.net/which/screw-plastic/) — A thread-forming screw designed for plastic, or a heat-set threaded insert where the joint will be undone more than once.
- [Which screw should I use for roofing sheets?](https://atoneplace.net/which/screw-roofing/) — A hex-head screw with a bonded EPDM washer, driven until the washer just spreads — no further.
- [How do I drive brass screws without snapping them?](https://atoneplace.net/which/screw-brass-hardware/) — Cut the thread with a steel screw of the same size first, wax the brass one, and use a driver that fits the slot exactly.

## Cable and wire

- [Which extension lead should I use for a heavy load?](https://atoneplace.net/which/wire-extension-lead/) — One with a conductor rated for the full load, and always fully unwound — a coiled cable reel can be derated to a fraction of its rating.
- [Which cable size is used for socket circuits?](https://atoneplace.net/which/wire-socket-circuit/) — Typically 2.5 mm² for a UK ring final on a 32 A device, or 12 AWG on a US 20 A branch circuit — subject to the code and the installation method.
- [Which wire size should I use for a 12 V circuit?](https://atoneplace.net/which/wire-12v-dc/) — Size it for voltage drop, not current — at 12 V a small drop is a large percentage, so the cable is far thicker than the amps suggest.
- [Which cable size is used for a lighting circuit?](https://atoneplace.net/which/wire-lighting-circuit/) — Typically 1.0 or 1.5 mm² twin and earth in the UK, or 14 AWG on a 15 A circuit in the US — but the code and the installation method decide.
- [Which cable should I use outdoors or underground?](https://atoneplace.net/which/wire-outdoor/) — Steel wire armoured cable, or a direct-burial type, at the required depth with RCD or GFCI protection — never ordinary indoor cable.
- [Which cable size does an electric shower need?](https://atoneplace.net/which/wire-electric-shower/) — Commonly 6 or 10 mm² depending on the shower rating, the run length and the installation method — and it is notifiable work in most jurisdictions.
- [Which speaker cable should I use?](https://atoneplace.net/which/wire-speaker/) — 16 AWG for short runs and 14 AWG beyond about 15 metres or into low-impedance speakers — and make sure it is copper, not copper-clad aluminium.

## Pipe

- [Which pipe should I use for hot and cold water?](https://atoneplace.net/which/pipe-hot-cold-water/) — Copper or PEX for most installations — PEX is faster and more freeze-tolerant, copper is more robust and takes heat without question.
- [Which pipe should I use for waste and drainage?](https://atoneplace.net/which/pipe-waste/) — Solvent-weld or push-fit PVC-u or polypropylene, at the right diameter and fall — and ABS and PVC cements are not interchangeable.
- [Which pipe should I use for central heating?](https://atoneplace.net/which/pipe-central-heating/) — Copper, or a barrier-grade plastic pipe — non-barrier plastic lets oxygen into the system and corrodes it from the inside.
- [Which pipe should I use for a boiler condensate drain?](https://atoneplace.net/which/pipe-condensate/) — Plastic, never copper, at a generous diameter with continuous fall — and insulate any external run, because frozen condensate is the classic winter breakdown.
- [Which pipe is used for gas?](https://atoneplace.net/which/pipe-gas/) — Steel, copper of the right grade, or yellow MDPE underground — and in most jurisdictions only a registered installer may do the work.
- [Which pipe should I use for a buried water supply?](https://atoneplace.net/which/pipe-underground-water/) — Blue MDPE for potable water, in one continuous length at the required depth, with no joints under a building.
- [Which pipe should I use for compressed air?](https://atoneplace.net/which/pipe-compressed-air/) — Copper, steel, stainless or a purpose-rated aluminium or HDPE air system — never PVC, which fails explosively.
- [Which pipe should I use for irrigation?](https://atoneplace.net/which/pipe-irrigation/) — Low-density polyethylene tubing with barbed fittings for drip lines, and PVC or MDPE for buried mains.

## Lubricant

- [Which lubricant should I use on a bike chain?](https://atoneplace.net/which/lubricant-bike-chain/) — Wet lube for wet conditions, dry lube for dry and dusty ones, wax if you want the cleanest and lowest-friction option — and not a general penetrant.
- [Which lubricant should I use on a lock?](https://atoneplace.net/which/lubricant-lock/) — A dry lubricant — powdered graphite or a PTFE spray. Oil and general penetrating sprays gum locks up and are the classic way to ruin one.
- [Which lubricant stops a squeaky door hinge?](https://atoneplace.net/which/lubricant-door-hinge/) — A drop of light machine oil or a smear of white lithium grease on the pin — and lift the pin out to clean it, which is usually the actual fix.
- [Which penetrating fluid frees a seized bolt?](https://atoneplace.net/which/lubricant-seized-bolt/) — A dedicated penetrant or a 50/50 acetone and automatic transmission fluid mix, plus time, heat cycles and shock — and anti-seize on reassembly.
- [What should I put on a squeaky floorboard?](https://atoneplace.net/which/lubricant-squeaky-floor/) — Talc, graphite or powdered soapstone worked into the joint as a stopgap — the real fix is screwing the board down to the joist.
- [What should I put on a sticky drawer?](https://atoneplace.net/which/lubricant-sticky-drawer/) — Paraffin wax or beeswax on wooden runners, dry PTFE on metal ones — and never oil on wood.
- [Which lubricant is safe on rubber seals?](https://atoneplace.net/which/lubricant-rubber-seal/) — Silicone grease on most rubbers, and a PTFE or fluorosilicone product on silicone rubber itself — petroleum products swell and destroy natural rubber and EPDM.
- [Which lubricant should I use on a garage door?](https://atoneplace.net/which/lubricant-garage-door/) — White lithium grease or a garage-door lubricant on rollers, hinges, springs and bearings — and not on the track, which should be clean and dry.

## Common questions

### Why will nothing stick to polypropylene?

Its surface energy is too low for adhesives to wet it, so the glue beads rather than spreading. A dedicated polyolefin primer changes the surface chemistry; a stronger glue does not help.

### Is WD-40 a lubricant?

No. It is a water displacer and penetrant. It evaporates and can carry away existing grease, which is why locks in particular get worse after repeated use.

### Which drill bit for tile?

A spear-point carbide bit for ceramic, a diamond bit for porcelain, always in rotary mode. Hammer action shatters tile.