How to Get a Dark Spot Out of Granite: A Comprehensive Guide

There I was, admiring my brand-new granite countertops. They gleamed under the kitchen lights, a testament to my recent renovation splurge. Then it happened. A rogue drop of olive oil, seemingly innocent, landed squarely in the center of my beautiful, light-colored granite. I wiped it up almost immediately, or so I thought. The next morning, a dark, insidious stain had bloomed, mocking my efforts. Panic set in. How do you get a dark spot out of granite? This was precisely the kind of nightmare scenario I’d worried about, and now it was a reality. My heart sank, picturing a permanent blemish on my otherwise pristine kitchen. But after a bit of frantic research and some trial-and-error, I discovered that getting a dark spot out of granite isn't always an insurmountable task. With the right approach and a bit of patience, you can often restore your granite to its former glory.

This article is born from that very experience and the subsequent deep dive I took into understanding granite care. Granite is a fantastic material – durable, beautiful, and relatively low-maintenance. However, it’s not entirely impervious to staining, especially when it comes to organic or oil-based substances. Understanding the nature of granite and the types of stains it's susceptible to is the first step in effectively tackling those unsightly dark spots. We'll explore why these spots appear, what materials are often the culprits, and most importantly, a range of techniques you can employ to remove them. My goal is to provide you with a thorough, practical guide, drawing on both established best practices and my own hard-won lessons. So, if you're staring at a dark spot on your granite right now and feeling that familiar pang of dread, take a deep breath. You’ve come to the right place.

Understanding Granite and Its Porosity

Before we dive headfirst into stain removal techniques, it's crucial to understand a fundamental characteristic of granite: its porosity. While granite is celebrated for its hardness and durability, it's also a natural stone, and like most natural stones, it has microscopic pores. Think of it like a very fine sponge. These pores are what allow the stone to absorb liquids. The degree of porosity can vary significantly depending on the specific type of granite. Some granites are naturally denser and less porous, while others, particularly lighter-colored ones, might absorb liquids more readily.

This inherent porosity is why sealing your granite countertops is such a vital step in their maintenance. A good quality sealant fills these tiny pores, creating a barrier that prevents liquids from seeping into the stone. However, even with proper sealing, no sealant is entirely foolproof. If a spill is left to sit for an extended period, or if the sealant has begun to wear down over time, there's still a possibility of absorption. This is precisely how those dreaded dark spots form. A liquid, particularly one that is oil-based or contains pigments, penetrates these microscopic openings and gets trapped within the stone's matrix, resulting in a visible discoloration.

My initial thought was that granite was completely stain-proof. This, as I learned the hard way, is a misconception. While it's highly resistant, it’s not impermeable. Understanding this allows us to approach stain removal with realistic expectations and the right strategies. The darker the spot, the deeper it has likely penetrated, and the more persistence might be required.

Identifying the Culprit: Common Causes of Dark Spots on Granite

To effectively tackle a dark spot on your granite, it’s incredibly helpful, if not essential, to identify what caused it in the first place. Different types of stains respond best to different cleaning agents. This is where detective work comes into play. Here are some of the most common culprits behind those unsightly dark spots:

Oils and Greases: This is, by far, the most frequent offender, and it was the culprit in my own case. Cooking oils, butter, bacon grease, salad dressings, and even oily residues from lotions or cosmetics can easily seep into granite. Oil-based stains are particularly notorious for creating dark, persistent marks because they penetrate deeply and can oxidize over time, making them harder to lift.
Organic Stains: These come from plant or animal matter. Think coffee, tea, wine, fruit juices, food scraps, pet accidents, or mold and mildew. While some organic stains might be lighter, they can also leave behind dark residues, especially if they sit for a while.
Water Stains and Mineral Deposits: While these often appear as lighter rings or cloudy patches, in some cases, particularly with hard water or if the water contains dissolved minerals that react with the granite, they can leave behind darker, more stubborn marks. This is less common for truly "dark spots" and more for what might be called a persistent dullness or discoloration.
Metal Stains: Rust from metal cans, cookware, or even certain types of fixtures can leach into the granite, creating reddish-brown or dark rust-colored stains.
Ink and Dyes: Marker pens, permanent inks, or even spills from colored beverages like red wine or dark sodas can penetrate the stone and leave behind a noticeable dark mark.
Chemical Stains: While less common for casual kitchen spills, certain harsh chemicals or cleaning products, especially those containing strong acids or alkalis, could potentially etch or discolor granite, leading to dark spots.

In my experience, the oil-based stains are the most challenging because they seem to cling to the stone’s matrix. Identifying the stain type will guide you toward the most effective cleaning method. If you’re unsure, start with the gentlest methods first and gradually move to more aggressive ones. It's always a good idea to test any cleaning solution on an inconspicuous area of your granite first to ensure it doesn't cause further damage or discoloration.

The Power of Poultices: Your Go-To for Tough Granite Stains

When it comes to removing stubborn dark spots from granite, the "poultice" method reigns supreme. A poultice is essentially a paste made from an absorbent material mixed with a cleaning agent. Its magic lies in its ability to draw the stain *out* of the stone. Think of it like a miniature, targeted suction device for your granite. The absorbent material, like baking soda or diatomaceous earth, works to wick the liquid stain away from the stone as it dries. I’ve found that the effectiveness of a poultice is directly related to the quality of the absorbent material and the appropriate cleaning agent for the specific stain type.

Here’s a breakdown of how to create and apply a poultice, which will be a recurring theme in our stain removal strategies:

Creating Your Poultice: The Basic Recipe

Choose Your Absorbent Material: Common and effective choices include:
- Baking Soda: Readily available and works well for many common stains.
- Diatomaceous Earth (Food Grade): Highly absorbent, excellent for drawing out deep-set stains. You can usually find this at garden supply stores or online.
- Kaolin Clay or Fuller's Earth: These are also very effective absorbent powders.
- White Flour: In a pinch, regular all-purpose flour can work, though it might be a bit less efficient than specialized powders.
Select Your Cleaning Agent: This is where stain identification is crucial.
- For Oil-Based Stains: This is where things get interesting. A mild dish soap (like Dawn) mixed with water is often surprisingly effective. For tougher oil stains, you might need a stronger solvent. Acetone (nail polish remover – ensure it’s 100% acetone and not a scented or colored variety) or a mineral spirit can be very powerful. Ammonia can also be effective for breaking down grease. Always test these solvents in an inconspicuous spot first, as they can potentially affect some sealants or even etch certain types of granite.
- For Organic Stains (Coffee, Tea, Wine, Food): Hydrogen peroxide (a 12% solution is often recommended for tough stains, but start with a standard 3% solution if you’re concerned) is excellent for bleaching out organic dyes. You can also use a diluted ammonia solution.
- For Water Stains/Mineral Deposits: While poultices aren't the primary solution here (more on that later), a poultice with a mild acidic solution like diluted white vinegar or lemon juice *might* help, but caution is advised as acids can etch granite.
- For Rust Stains: Specialized rust removers designed for stone are best. Some poultices can be made with a commercial rust remover, but follow product instructions carefully.
Mix to a Paste: Gradually add your cleaning agent to the absorbent material, mixing until you achieve a thick, peanut-butter-like consistency. It should be spreadable but not runny.

Applying the Poultice: The Step-by-Step Process

Clean the Area: Gently clean the stained area with a mild soap and water and dry it thoroughly. This removes any surface debris that could interfere with the poultice.
Apply the Poultice: Using a spatula or plastic putty knife, apply a layer of the poultice about ¼ to ½ inch thick directly over the dark spot. Extend it slightly beyond the edges of the stain.
Cover and Seal: Cover the poultice with plastic wrap. Tape down the edges of the plastic wrap with painter's tape to create a seal. This prevents the poultice from drying out too quickly and allows it to work more effectively by keeping the cleaning agent active.
Let It Work: Allow the poultice to sit for at least 24 to 48 hours. The longer it’s on, the more it can draw out. You’ll notice the plastic wrap might become cloudy as moisture is drawn from the stone.
Remove the Poultice: Once the time is up, carefully remove the plastic wrap. The poultice should be dry and crumbly. Gently scrape it away with a plastic scraper or putty knife.
Clean and Assess: Clean the area with a mild soap and water and dry it thoroughly. Inspect the granite. Has the stain lightened or disappeared?
Repeat if Necessary: For very stubborn or deep stains, you may need to repeat the poultice process several times. It’s better to do multiple applications than to use excessively harsh chemicals or scrub too aggressively.

I can't stress enough how crucial patience is with this method. My first attempt at removing an oil stain took two full poultice applications over four days. The spot didn't vanish after the first go, and I was discouraged. But by the second, it was significantly lighter, and a third application made it virtually invisible. It’s about a process of drawing the stain out gradually.

Specific Strategies for Different Types of Dark Spots

Now, let's get specific. Based on the common culprits we discussed, here are tailored approaches to tackle those dark spots. Remember to always test in an inconspicuous area first!

Dealing with Oil and Grease Stains

This is where poultices truly shine. For fresh oil spills, your immediate action should be to blot, not rub. Absorb as much of the surface oil as possible with paper towels. Then, for slightly older or more ingrained oil stains:

Method 1: Baking Soda and Dish Soap Poultice

Absorbent: Baking soda.
Cleaning Agent: A few drops of mild liquid dish soap (like Dawn, known for its degreasing power) mixed with a little water.
Mix: Combine baking soda with the soapy water until you get a thick paste.
Apply: Apply as per the general poultice instructions above.
Why it works: The baking soda absorbs the oil, and the dish soap helps to break down the greasy components.

Method 2: Acetone or Mineral Spirits Poultice (for tougher stains)

Absorbent: Diatomaceous earth or kaolin clay.
Cleaning Agent: Acetone (100% pure) or mineral spirits.
Mix: Gradually add acetone or mineral spirits to the absorbent powder until a paste forms. Work in a well-ventilated area, and be aware that these are flammable. Avoid open flames.
Apply: Apply as per the general poultice instructions. Let it sit for 24-48 hours.
Why it works: These solvents are highly effective at dissolving grease and oil. They penetrate the stone and lift the oily residue.

Important Note on Solvents: If your granite is sealed with a topical sealant (which is less common for high-quality installations but can happen), acetone and mineral spirits can strip that sealant. If you’re unsure about your sealant type, or if you notice the granite becoming duller after using solvents, you may need to reseal the area afterward. For most professionally sealed granite, these solvents are safe for the stone itself.

Tackling Organic Stains (Coffee, Tea, Wine, Food Residue)

Organic stains often have pigments that can be lightened or bleached. Hydrogen peroxide is your best friend here.

Method: Hydrogen Peroxide Poultice

Absorbent: Baking soda or diatomaceous earth.
Cleaning Agent: Hydrogen peroxide (start with 3% solution; for very stubborn stains, a 12% solution, often found at beauty supply stores for hair bleaching, can be used with extreme caution). You can also add a few drops of ammonia for extra power, but again, test first.
Mix: Mix the absorbent with hydrogen peroxide to form a thick paste.
Apply: Apply the poultice to the stain and cover with plastic wrap.
Let it work: Allow to sit for 24-48 hours. Hydrogen peroxide works best when it has time to break down the organic pigments.
Why it works: Hydrogen peroxide is a mild bleaching agent that effectively breaks down and lightens organic dyes found in coffee, tea, wine, and food.

My Experience: I once had a red wine stain on my light-colored granite that I thought was a goner. A hydrogen peroxide poultice, applied twice, completely erased it. The key was letting it sit for the full 48 hours the second time around. It felt like a miracle!

Removing Ink and Dye Stains

Ink stains can be tricky, depending on the type of ink. For marker or pen ink, you might have some success with specific solvents.

Method: Acetone or Rubbing Alcohol

Cleaning Agent: 100% acetone or isopropyl alcohol (rubbing alcohol).
Application: Dampen a cotton ball or soft cloth with the acetone or alcohol. Gently dab the stain. Do not rub aggressively, as this can spread the ink. Work from the outside of the stain inward.
Follow-up: If the stain lightens, you can then try a baking soda paste mixed with a little water (not enough to make it too runny) applied to the area for a few hours. This can help draw out any remaining residue.
Poultice Option: For deeper ink stains, you can create a poultice using diatomaceous earth and acetone or rubbing alcohol.
Why it works: Acetone and rubbing alcohol are effective solvents for many types of inks.

Caution: Be very careful with colored markers or inks, as some dyes can be particularly stubborn. For permanent markers, this is where you might need to consult a professional stone restorer if gentle methods fail.

Addressing Metal Stains (Rust)

Rust stains on granite are usually caused by metal objects left on the surface, especially if the granite isn't sealed properly or if the object itself is already rusty. These can be tough.

Method: Specialized Rust Remover Poultice

Cleaning Agent: The most effective approach is to use a commercial rust remover specifically designed for natural stone. These often contain mild acids or chelating agents that break down rust. Follow the manufacturer’s instructions meticulously.
Poultice Creation: Many commercial rust removers are liquids. You’ll typically mix them with an absorbent material like diatomaceous earth or kaolin clay to create a poultice.
Application: Apply the poultice as per the general instructions, ensuring thorough coverage of the rust spot.
Why it works: Commercial rust removers are formulated to dissolve iron oxides without damaging the stone, and the poultice action draws the dissolved rust out.

DIY Caution: While some sources suggest using acidic cleaners like lemon juice or vinegar for rust, this is generally **not recommended for granite**. Acids can etch the stone, causing permanent dullness, which is often worse than the original rust stain. Stick to products specifically designed for stone.

Water Spots and Etching

While not typically "dark spots" in the sense of absorbed discoloration, persistent water spots or etching can appear as dull, sometimes darker-looking areas, especially on polished granite. These are usually caused by minerals in hard water or acidic substances.

Method: Gentle Polishing and Sealing

For minor etching/water spots: Sometimes, a good cleaning followed by buffing with a microfiber cloth is enough. If there's a slight residue, try a cleaner specifically designed for granite.
For more noticeable etching: This is where you might need to use a granite polishing compound. These are mildly abrasive and can help restore the shine. Follow the product instructions carefully. It might involve applying the compound, buffing with a felt pad or microfiber cloth, and then cleaning.
Resealing: After any aggressive cleaning or polishing, it’s always a good idea to reseal your granite to protect it against future issues.

Important: True etching on polished granite is a physical alteration of the surface, not a stain that can be "drawn out." Poultices won't fix etching. For deep etches, professional restoration might be necessary.

Preventative Measures: Keeping Your Granite Spot-Free

The best way to deal with a dark spot on granite is, of course, to avoid getting one in the first place! Prevention is always easier than cure, and with granite, a little proactive care goes a long way.

1. Seal Your Granite Regularly

This is non-negotiable. Sealing creates a barrier that prevents liquids from penetrating the stone. How often you need to reseal depends on the type of granite and the sealant used, but a good rule of thumb is once a year, or whenever you notice water no longer beads up on the surface. You can test your sealant by dripping a small amount of water on the countertop. If it beads up, your seal is good. If it darkens the stone or soaks in within a few minutes, it's time to reseal.

2. Clean Up Spills Immediately

This is the golden rule. Don’t let spills sit, especially oil-based liquids, wine, coffee, or acidic substances. A quick wipe-up with a soft cloth and a mild, pH-neutral cleaner designed for natural stone can save you a lot of heartache and effort later.

3. Use a pH-Neutral Cleaner

Harsh chemicals, especially acidic or alkaline cleaners (like bleach, ammonia, or vinegar), can damage the sealant and even etch the granite over time. Stick to cleaners specifically formulated for natural stone or use a mild solution of dish soap and water for daily cleaning. Always rinse thoroughly with clean water and dry with a soft cloth.

4. Be Mindful of Hot Pans and Cutting Boards

While granite is heat-resistant, prolonged exposure to extreme heat can potentially damage the sealant. Always use trivets or hot pads for hot pots and pans. Similarly, while granite is hard and scratch-resistant, using cutting boards will protect its surface from knife marks and prevent premature wear, especially on polished finishes.

5. Consider a Reputable Installer

When you have your granite installed, ensure the fabricator and installer are reputable and knowledgeable. They can advise you on the best type of sealant for your specific granite and ensure it's applied correctly.

When to Call a Professional Granite Restorer

While most common dark spots can be tackled with the methods outlined above, there are instances where it’s best to call in the professionals. Don’t feel defeated if you can’t remove a stain yourself; sometimes, DIY attempts can exacerbate the problem.

You should consider calling a professional if:

The Stain Persists After Multiple Attempts: If you've tried several poultice applications with no significant improvement, the stain might be deeply set or of a nature that requires specialized knowledge.
You're Unsure of the Stain Type: If you have absolutely no idea what caused the spot, a professional can often identify it and employ the most effective treatment.
The Stain is Extensive or Severe: Large, deep, or multiple stains across a significant area might be best handled by someone with commercial-grade equipment and expertise.
You've Accidentally Damaged the Granite: If you've used the wrong cleaner and caused etching, discoloration, or other damage, a professional restorer has the tools and compounds to repair the surface.
You Have a Rare or Particularly Delicate Granite: Some exotic granites might be more sensitive to certain cleaning agents. A professional will know how to handle them.

Professionals have access to a wider range of specialized cleaning agents, diamond polishing pads, and equipment that can address issues beyond typical household remedies. They can often assess the situation quickly and provide a more efficient, and ultimately cost-effective, solution than repeated, potentially unsuccessful DIY attempts.

Frequently Asked Questions About Dark Spots on Granite

Q1: How long does it typically take to remove a dark spot from granite?

The timeline for removing a dark spot from granite can vary greatly depending on the type of stain, how deeply it has penetrated, and the specific granite you have. For fresh, surface-level stains, a simple wipe-up might be all that's needed. For more ingrained stains, the poultice method is usually the most effective. This process can take anywhere from 24 hours (for one application) to several days if multiple applications are required. Stubborn stains might necessitate two or three repeated poultice treatments, with 24-48 hours between each application to allow the stone to dry and the poultice to work. It’s important to be patient. Rushing the process or using overly aggressive scrubbing can sometimes cause more harm than good.

My personal experience with an oil stain on my light granite took two full 48-hour poultice applications to completely disappear. I was initially tempted to scrub or try a stronger chemical after the first attempt, but resisting that urge and repeating the gentle poultice method proved to be the key. It’s about allowing the absorbent material to draw the stain out gradually over time, rather than forcing it out with harsh methods. If you’ve completed multiple poultice applications and see little to no improvement, it might be time to consider the type of stain and whether professional intervention is needed.

Q2: Why do oil-based stains cause darker spots on granite than water-based ones?

The primary reason oil-based stains create darker and more persistent spots on granite compared to water-based ones is due to the fundamental chemical properties of oils and water, and how they interact with the porous nature of stone. Granite, as we’ve discussed, is a natural stone with microscopic pores. While it’s sealed, sealants are not entirely impermeable, and liquids can still penetrate if left to sit.

Water is a polar molecule. When water-based liquids like coffee, tea, or fruit juice spill, they can penetrate the pores. However, water-based stains often contain pigments or organic matter that can be more easily broken down or bleached by cleaning agents like hydrogen peroxide. Oil, on the other hand, is non-polar. It has a different molecular structure. When oil penetrates the granite’s pores, it can spread and become trapped more easily. Furthermore, oils can oxidize over time when exposed to air and light. This oxidation process can darken the oil itself, making the stain appear more intense and visually prominent, especially against lighter granite. Think of how an old cooking oil stain on a fabric becomes darker and more yellowed over time – a similar principle applies to stone.

The difficulty in removing oil stains also stems from the fact that standard water-based cleaners aren’t always effective at breaking down and lifting grease. This is why degreasers and solvents like acetone or ammonia are often more successful for oil stains, as they are formulated to tackle that specific type of residue. The poultice method is particularly effective for oil because the absorbent material physically wicks the oily liquid out of the stone as it dries, a process that works much more efficiently than trying to dissolve and rinse oil with just water.

Q3: Can I use common household cleaners like bleach or vinegar to get a dark spot out of granite?

It is strongly advised to avoid using common household cleaners like bleach or vinegar directly on granite, especially for stain removal. While they might seem like powerful cleaning agents, they can actually cause more harm than good to your granite surfaces. Vinegar is an acid, and even diluted, it can etch polished granite. Etching is not a stain that can be removed; it's a physical alteration of the stone's surface, leaving it dull and less reflective. This is often more noticeable and harder to fix than the original stain.

Bleach, while a disinfectant and capable of whitening, is also a harsh chemical. It can strip the granite’s sealant, leaving it more vulnerable to future staining. In some cases, it can even react with certain minerals in the granite, potentially causing discoloration or a dulling effect. Ammonia, another common household cleaner, can also be harsh and damage sealants. For effective stain removal on granite, it is best to use pH-neutral cleaners specifically designed for natural stone, or to employ methods like poultices that use gentle, stain-specific cleaning agents.

If you are dealing with a persistent stain, your safest bet is to consult the methods described in this article, which focus on targeted treatments like poultices. If you are unsure about the type of stain or the best approach, it is always recommended to consult with a professional stone care specialist. They have the knowledge and products to address stains effectively without damaging your beautiful granite.

Q4: What is the best way to prevent future dark spots on my granite countertops?

Preventing future dark spots on your granite countertops involves a combination of consistent care and proactive measures. The most crucial step, as mentioned earlier, is ensuring your granite is properly and regularly sealed. A good sealant acts as a protective barrier, giving you more time to wipe up spills before they can penetrate the stone. Test your sealant periodically by dripping a small amount of water onto the surface; if it beads up, the seal is intact. If it soaks in or darkens the stone, it's time to reseal.

Beyond sealing, the most effective preventative measure is prompt cleanup of spills. Never let liquids, especially oil-based products, wine, coffee, acidic foods, or anything with strong dyes, sit on your granite for an extended period. Blot up spills immediately with a soft cloth or paper towel. For daily cleaning, use a pH-neutral cleaner specifically formulated for natural stone, or a very mild solution of dish soap and water. Always rinse the surface with clean water after cleaning to remove any residue, and then dry it thoroughly with a soft, lint-free cloth. This prevents water spots and streaks.

Additionally, be mindful of items that can cause damage. Use trivets or hot pads under hot pans and dishes to protect the sealant from heat damage. Use cutting boards when preparing food to avoid scratching or dulling the surface. Avoid placing items that can rust, like metal cans or old cookware, directly on the granite surface, as these can leave rust stains. By incorporating these simple habits into your routine, you can significantly minimize the risk of developing new dark spots and keep your granite looking beautiful for years to come.

Q5: If I use a solvent like acetone or mineral spirits for a stain, will it damage my granite permanently?

Using solvents like acetone or mineral spirits to remove dark spots from granite is generally safe for the stone itself, provided you follow certain precautions. These solvents are effective at breaking down oil-based stains because they are excellent at dissolving grease and oil. The granite material itself is typically resistant to these chemicals.

However, the main concern with using such solvents is their potential impact on the granite's sealant. Many sealants, particularly topical sealants (which are less common on professionally installed granite but can be found on some DIY applications or older installations), can be weakened or stripped by strong solvents like acetone. If your granite is sealed with a topical sealant, using acetone might remove or damage this protective layer, leaving the stone more vulnerable to future staining. If your granite has an impregnating sealant (which soaks into the stone), it is usually more resistant to these solvents.

To mitigate this risk, it's always recommended to test the solvent in an inconspicuous area first. If you notice that the solvent dulls the shine or seems to lift a layer from the granite, stop immediately. After using acetone or mineral spirits to remove a stain, it's a good practice to clean the area with a pH-neutral cleaner and then reapply a granite sealant to that specific spot or the entire countertop to ensure adequate protection moving forward. If you are unsure about your sealant type or if the granite appears damaged after solvent use, consulting a professional stone restorer is the safest course of action.

Conclusion: Restoring Your Granite's Beauty

Dealing with a dark spot on your granite might seem daunting at first, but as we've explored, there are effective and often straightforward methods to tackle these blemishes. Understanding the nature of granite, identifying the cause of the stain, and employing the right techniques, particularly the power of the poultice, can make all the difference. My own journey from panic to resolution with my olive oil stain taught me valuable lessons about patience, persistence, and the efficacy of targeted cleaning. Remember, most common dark spots are not permanent scars but rather temporary visitors that can be encouraged to leave with the right approach.

Always start with the gentlest method suitable for the suspected stain type. When in doubt, a baking soda paste or a hydrogen peroxide poultice can be a good starting point. For tougher, oil-based stains, a poultice with acetone or mineral spirits (with proper ventilation and testing) might be necessary. And crucially, never underestimate the importance of preventative care. Regular sealing and prompt spill cleanup are your best defenses against future staining. If, after diligent effort, a stain persists, or if you’ve inadvertently caused damage, don’t hesitate to call a professional granite restorer. They have the expertise and tools to bring your countertops back to their original splendor. With this comprehensive guide, you're well-equipped to handle most dark spot emergencies and keep your granite countertops looking as stunning as the day they were installed.

How to Get a Dark Spot Out of Granite: A Comprehensive Guide